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Negative Poisson's ratio in auxetic structures plays a crucial role in energy absorption and impact mitigation. Origami-based lattices within the realm of auxetic structures offer the advantage of facile fabrication and design. Nevertheless, the utilization of periodic lattices in origami-based auxetic structures constrains the available design space for achieving diverse mechanical properties. Addressing this limitation, our study introduces origami-based auxetic structures with functionally graded thickness, utilizing origami-based lattices known as Tachi–Miura polyhedra. We investigated the impact of functionally graded thickness on buckling behavior and force responses through dynamic loading experiments employing 3D-printed test pieces. The experimental results indicate that functionally graded thickness induces partial auxetic deformation in lattices, and the resulting nonsymmetric deformation prevents global buckling, thereby averting bounded forces observed in structures with uniform thickness. These findings extend the applicability of auxetic structures, spanning from energy absorption to the design of cushioning structures. [ABSTRACT FROM AUTHOR]

The rapidly increasing demand for heavy vehicles in the transportation sector has led to more severe road damage and significantly higher road maintenance costs. Investigation of active suspension system incorporating vehicle–road interaction (VRI) can provide effective means to reduce the road damage and improve the ride comfort of vehicles. In this paper, an active vehicle suspension controller based on the strongly stable and robust linear–quadratic regulator (LQR) principle is developed for the time-varying VRI system. The coupled system is modeled by a quarter-car traveling on the road modeled by an Euler–Bernoulli beam resting on a viscoelastic foundation. Two types of road irregularities, deterministic sine wave and random, are considered in the numerical studies. A time-frozen technique, by which the linear time-varying system is converted to a time sequence of time-invariant systems, is applied to solve for the coupled responses. Three variables, the dynamic tire load, vehicle body acceleration, and suspension relative displacement, are used to assess the effectiveness of the LQR-based controller in comparison to the passive suspension system. The performance of the active control is investigated for different vehicle speeds, vehicle loads, and road profiles. Numerical studies show that the controller can effectively reduce the road damage and improve the ride comfort, with a slight increase in the suspension relative displacement. This work lays a useful foundation in the problem formulation and system parameter influences for future vehicle suspension design and road damage mitigation including VRI. [ABSTRACT FROM AUTHOR]

This study investigates stress-deformation behavior in Himalayan tunnels, focusing on how geological features impact stability. The objective is to enhance the understanding of displacement phenomena, particularly in tunnels traversing jointed rocks. A modified support system, to specific rock mass classifications, is employed to address the unique challenges posed by geological discontinuities. Kinematic analysis reveals a 20% probability of wedge failure due to these discontinuities. Numerical analysis using Hoek–Brown parameters identifies significant stress concentrations at the tunnel crown, especially in jointed sections, where increased convergence and displacement (1.2 mm at the crown compared to 0.25 mm at the walls) highlight the susceptibility to deformation. The study indicates the critical need for specialized support in jointed regions to mitigate stability risks. Article highlights: This study contributes understanding of complex interactions between geological features and tunnel stability, regarding stress-deformation phenomena in Himalayan tunnels. The analysis identifies significant stability concerns, including a concerning 20% probability of wedge failure and increasing stress levels at the tunnel crown. It underscores the importance of support systems and proactive risk management strategies to mitigate instability risks, particularly in ultramafic sections characterized by higher stresses. The research highlights the importance of considering dynamic loading conditions, validation with field data, and long-term variations in stress and deformation for a comprehensive understanding of tunnel stability. Future investigations should explore the influence of groundwater flow and seismic information, to examining advanced support systems. [ABSTRACT FROM AUTHOR]

Glenoid loosening, primarily induced by the “rocking horse” phenomenon from humeral head load on the glenoid rim, is the foremost complication and cause of failure in anatomic total shoulder arthroplasty. The dynamic load exerted by universal fatigue testing machines significantly deviates from the standard ASTM F2028-14 in the rocking test. To accurately conduct the in vitro loosening test on anatomic glenoids, a specialized system and customized test methods are developed to achieve anatomic glenoid rocking and subluxation tests. The horizontal and vertical loading can be achieved synchronously or asynchronously by two self-developed high-performance electromagnetic linear motors. In addition, the subluxation tests on anatomic glenoids are verified by finite element simulation. The results show that the subluxation load and translation of anatomic glenoids in the subluxation tests are consistent with those in numerical simulations. The error of the applied axial force in the rocking tests is only 5N, strictly meeting the standard of ASTM F2028-14. During the rocking tests, the system runs smoothly and the software works well, indicating the feasibility of the in vitro shoulder joint test system. This study provides an approach to accurate dynamic evaluation of glenoid loosening or disassociation. [ABSTRACT FROM AUTHOR]

The operation and service performance of ballasted track on bridges face significant challenges due to high-speed railway train operations. To investigate the mechanical characteristics of ballasted track on bridges, field experiments were conducted. A coupling model of ballasted track on a simply-supported girder bridge was established using the coupling method of discrete element and multi-flexible body dynamics and analyzes the changes in ballast bed settlement deformation, stiffness and energy with increasing load cycles. The findings reveal that dynamic loading alters the original contact state of ballast particles, displaying notable anisotropy vertically and longitudinally and isotropy horizontally. The vibration of ballast particles on bridges is more pronounced than on the subgrade, with vibration acceleration under the sleeper at 150mm depth on the bridge being 2.89 times that on the subgrade foundation. As the system stabilizes, the interlocking effect among granular ballast particles strengthens, reducing mutual sliding and increasing ballast bed stiffness by approximately 7.8–9.5% compared to the initial state, while total energy and dissipated energy gradually decrease. It is recommended to monitor the quality of ballast particles under the sleeper of ballasted tracks on bridges, implement vibration mitigation measures, or periodically replace ballast particles. [ABSTRACT FROM AUTHOR]

The mechanism of rock burst induced by the superposition of dynamic and static loads in multicoal seam mining is unique. To investigate the propagation attenuation law of large‐energy microseismic events and the induced mechanism of rock burst under this condition, this study employs FLAC3D's dynamic module to simulate and analyze the influence of propagation distance, overburden structure in multicoal seam mining, and interlayer plastic zone on vibration wave attenuation. Results indicate that when coal seams are mined at close distances, vibration waves experience significant attenuation while passing through the plastic zone between two layers of coal. At equal attenuation distances, multicoal seam mining structures exhibit greater effects on vibration wave attenuation. Considering differences between rock‐burst induction mechanisms in close‐distance coal seam group mining versus single coal seam mining, a discriminant criterion for rock bursts induced by superimposed dynamic and static loads in multicoal seam mining is established along with a monitoring and early warning method suitable for such conditions. [ABSTRACT FROM AUTHOR]

Accurately predicting the degradation and remaining useful life (RUL) of Proton Exchange Membrane Fuel Cells (PEMFCs) is crucial for enhancing their reliability, particularly in automotive and energy sectors. Traditional models often fail to capture the complex, non-linear degradation patterns of PEMFCs, resulting in suboptimal predictions. This study addresses these technological gaps by introducing a novel approach, the Self-Attention Temporal Dual Discriminator Generative Adversarial Network (SAT-DD-GAN). This model is designed to overcome the limitations of existing methods by integrating advanced Long Short-Term Memory (LSTM) networks for time-series analysis, a self-attention mechanism to focus on critical degradation signals, and dual discriminators to improve prediction accuracy and robustness. By addressing the gap in handling long-term dependencies and complex degradation patterns, the proposed SAT-DD-GAN bridges the disconnect between traditional models and the real-world degradation behavior of PEMFCs. The SAT-DD-GAN achieved groundbreaking predictive performance, with the lowest RMSE (0.983E-3 for static load, 1.012E-3 for dynamic load), MAPE (0.036E-1 and 0.253E-1), MAE (0.776E-3 and 0.806E-3), and the highest R2-score (0.9998 and 0.9983), alongside zero relative error for both datasets. These results demonstrate the model's ability to capture the intricate degradation dynamics more effectively than existing state-of-the-art methods. By filling the technology gap of accurately modeling PEMFC degradation under varying load conditions, this study establishes a new standard for PEMFC prognostics and paves the way for future innovations in optimizing fuel cell performance and longevity. • Introduced a novel SAT-DD-GAN model for accurate prediction of PEMFC stack voltage degradation and Remaining Useful Life (RUL). • Innovatively combined LSTM, self-attention, and dual discriminator mechanisms for enhanced predictive robustness. • Achieved superior accuracy, with RMSE as low as 0.000983 (static load) and R2-score of 0.9998 (static load). • Demonstrated advanced handling of static and dynamic loads, outperforming recent models in key prediction metrics. • Set a new benchmark in predictive maintenance for PEMFCs, offering potential advancements in neural network-driven prognostics. [ABSTRACT FROM AUTHOR]

Arc devices are among the receivers with the highest power connected to power systems. Due to dynamic load changes, these receivers generate a number of disturbances that affect the quality of electric power. The most important disturbances include voltage fluctuations. It is also worth mentioning the asymmetry and deformation of the supply voltage curve. This article discusses the mutual interaction of receivers operating in parallel, operating stably, and devices with dynamic current consumption. Calculations based on model tests and the results of parameters characterizing the quality of energy, which were recorded in the line supplying the steelworks, are presented. The power supply conditions (power of the short-circuit network) were assessed to influence the degree of suppression of voltage fluctuations by loads with stable current consumption. [ABSTRACT FROM AUTHOR]

In a multi-fed DC environment, the UHV DC recipient grid faces significant challenges related to DC phase shift failure and voltage instability due to the high AC/DC coupling strength and low system inertia level. While the new large-capacity synchronous condensers (SCs) can provide effective transient reactive power support, the associated investment and operation costs are high. Therefore, it is valuable to investigate the optimization of SC configuration at key nodes in the recipient grid in a scientific and rational manner. This study begins by qualitatively and quantitatively analyzing the dynamic characteristics of DC reactive power and induction motors under AC faults. The sub-transient and transient reactive power output model is established to describe the SC output characteristics, elucidating the coupling relationship between the SC's reactive power output and the DC reactive power demand at different time scales. Subsequently, a critical stabilized voltage index for dynamic loads is defined, and the SC's reactive power compensation target is quantitatively calculated across different time scales, revealing the impact of transient changes in DC reactive power on the transient voltage stability of the multi-fed DC environment with dynamic load integration. Finally, an optimal configuration model for the large-capacity SC is proposed under the critical stability constraint of dynamic loads to maximize the SC's reactive power support capability at the lowest economic cost. The proposed model is validated in a multi-fed DC area, demonstrating that the optimal configuration scheme effectively addresses issues related to DC phase shift failures and voltage instability resulting from AC bus voltage drops. [ABSTRACT FROM AUTHOR]

The field load test is a direct and effective method for evaluating the performance of bridge structures. However, existing bridge field static load tests are costly and inefficient; moreover, they obstruct traffic and cause unavoidable damage to the bridge structure. As an alternative the the static load test, a random model update method based on bridge dynamic load tests and the Bayesian inference is proposed in this paper. The bridge static load test results were predicted with a high accuracy. To speed up the Bayesian method to infer the posterior probability density of the updated parameters, the Gaussian process was used in place of the finite element model, and the Bayesian inference used the Markov chain Monte Carlo method based on the delayed rejection adaptive Metropolis algorithm. First, the parameters to be modified for the bridge structure analysis model were determined based on the global sensitivity analysis method. Second, a uniform design sampling method was used to establish the Gaussian process optimization model to update the random model of the bridge structure. Finally, a reinforced concrete truss arch bridge was used to verify the correctness of the static load results of the bridge predicted by the random model update method based on dynamic load testing and Bayesian inference. The research results reveal that the prediction results of the bridge static load test based on the dynamic load test and Bayesian inference method agree with the actual test results. [ABSTRACT FROM AUTHOR]

Under dynamic conditions, the response time of traditional voltage detection methods is relatively lengthy, leading to overshoots in the DC-link voltage of single-phase power converters, which significantly degrades system performance. This study proposes a rapid voltage transient detection method based on reduced-order generalized integrator (ROGI) aimed at improving the response speed of bus voltage peak detection. By reducing the order of the algorithm, this method shortens the generation time of orthogonal signals and accelerates the detection speed of voltage changes. This enables grid power to rapidly compensate for the load power under dynamic conditions while maintaining a high-precision complementarity of the split capacitor voltage. As a result, it effectively diminishes severe fluctuations in DC-link voltage, which increases the stability of the system under dynamic load changes. This paper meticulously derives the relationship between capacitor voltage changes and grid response delays, and constructs the ROGI algorithm and its control scheme, ensuring the robustness of the method in the presence of system parameter variations. Finally, to validate the effectiveness of the proposed method, a hardware experimental platform is established and tested. Results of load step response experiments indicate that the ROGI algorithm, in comparison to traditional detection methods, reduces the detection time by 40.9%. [ABSTRACT FROM AUTHOR]

A vehicle's dynamic load is the force exerted on the tire by the road when the vehicle is in motion. The road is damaged not just by the vehicle's horizontal and vertical forces, but also by the vertical forces generated by the vehicle's movement. However, road surface impacts also increase dynamic load and shorten tire life, both of which reduce dynamic safety. This research aims to determine the impact of road condition and vehicle speed on the dynamic load acting on the multi-purpose forest firefighting vehicle. The author created a model using differential equations to describe vehicle vibrations by separating a multi-body system. Using MATLAB software to survey and determine the dynamic load coefficient on the multi-purpose forest firefighting vehicle as it travels over ISO 8608:2016 roads at different speeds. Within the parameters of the standard working speed range, According to ISO standards, the maximum dynamic load factor at the front and the rear left wheel on each of the four types of roads rise in direct proportion to the speed at which the vehicle is moving and the height of the road surface. When a vehicle is traveling at a speed of 25 km per hour on the worst type of road that the author assessed, which was a class E road, the dynamic load coefficient's maximum value has the following values: maxkd11 = 2.71, maxkd31 = 2.75. The rate of travel and the elevation of the roadway both affect the dynamic load coefficient that the vehicle experiences. The findings from the research are going to be used as the foundation for finishing the building of the multi-purpose forest firefighting vehicle. [ABSTRACT FROM AUTHOR]

This paper aims to examine the behavior of cracked adhesive joints experimentally and numerically when they are subjected to quasi-static and dynamic loads using the tensile and falling-wedge impact tests, respectively. Double cantilever beam (DCB) specimens were manufactured and tested under impact loading with varying impact energies to analyze the adhesive joint mode-I dynamic fracture response. To determine quasi-static and dynamic mode-I fracture energies, the compliance-based beam method (CBBM) was utilized accounting for the axial force exerted by the wedge. It was found that by changing the loading condition from quasi-static to impact, the maximum force and fracture energy of adhesively bonded joints were considerably increased by 275% and 452%, respectively. However, within the impact test conditions, increases of 10% and 22% were obtained in maximum force and fracture energy when the impact energy was tripled. The adhesive joints tested under static loading experienced a mixed interfacial/cohesive failure pattern, whereas by shifting the loading condition to impact, the failure pattern turned fully cohesive. The quasi-static and dynamic fracture responses of adhesive joints were modeled using the cohesive zone model employing a triangular traction-separation law. The numerical and experimental results exhibited reasonable correlation. [ABSTRACT FROM AUTHOR]

With rapid industrial development, the overloading of bridges caused by heavy multi-axle vehicles has become a critical problem worldwide. This work conducts a performance-based evaluation for tied-arch bridges subjected to heavy multi-axle vehicles, and a prediction function of the dynamic impact factor (DIF) for tied-arch bridges is proposed considering the bridge frequency, vehicle speeds, and road quality level. Specifically, the main parameters affecting the bridge response were first identified theoretically using a simplified multi-axle vehicle-bridge model. A tractor-trailer mechanical model and a tied-arch bridge model were subsequently constructed and coupled using displacement coordination conditions to explore the characteristics of the bridge response under heavy multi-axle tractor-trailers. Additionally, based on the identified factors, a detailed investigation of DIF was performed using the developed special vehicle-bridge interaction model. Finally, a suggested computational method for predicting DIF of tied-arch bridges was proposed. The results obtained indicate the impact effect of special tractor-trailers on bridges should not be ignored, even at low operating speeds and in good road conditions. Moreover, additional monitoring measures should be placed on the structural components that are sensitive to dynamic responses to regulate responses within an acceptable range. [ABSTRACT FROM AUTHOR]

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As part of the Ultra High Aspect Ratio Wing Advanced Research and Designs (U-HARWARD) project, funded by CS2JU, various gust load alleviation (GLA) technologies have been developed and studied. GLA plays a crucial role in the development of new generation ultra-high aspect ratio wings (UHARWs), as it reduces gust loads, thereby decreasing the structural weight of the wing and, consequently, the entire aircraft. This weight reduction enhances overall aircraft efficiency, enabling a higher aspect ratio. GLA technologies are categorized into passive systems, which require no active intervention, and active systems, where control surfaces redistribute the aerodynamic loads. In this study, passive GLA was implemented using a folding wing tip (FWT) developed by the University of Bristol, while active GLA employed a Static Output Feedback controller developed by Politecnico di Milano. Both approaches were compared against a baseline aircraft configuration. A flutter assessment confirmed that FWT does not introduce aeroelastic instabilities, ensuring the aircraft remains flutter-free across its flight envelope. A thorough comparison of load envelopes, based on nearly 2000 load cases across different flight points and mass configurations, was conducted in compliance with CS25 regulations, examining both positive and negative gust conditions. The results show a possible 15% reduction in the dynamic load envelope for both passive and active solutions. Using NeOPT, a hybrid finite element (FE) model was developed, with a detailed global FEM (GFEM) for the wingbox and stick elements for other components. Linear gust analyses in Nastran, with the hinge locked and released, provided high-fidelity results, comparing wing failure indexes and demonstrating the effectiveness of the FWT solution. [ABSTRACT FROM AUTHOR]

Accurate identification of impact loads is vital for structural assessment and design. Traditional methods rely on complex equipment, such as accelerometers or strain gauge, which can be expensive and prone to failure. This study introduces a non-contact intelligent identification approach incorporating visual sensing technology, providing a convenient means to identify impact loads. Numerical simulations explore the differences in identifying impact forces through acceleration and displacement responses, particularly by considering such variables as measurement noise and number of measurement points. A meticulously designed experiment verified the feasibility of the proposed method for measuring the displacement and velocity of rapidly moving targets, and evaluated its performance in terms of accuracy. A series of impact loading experiments were conducted on a simply supported girder bridge model to validate the effectiveness of the proposed impact force identification method. Results indicate strong agreement between displacement response measurements and percentile meters. The proposed non-contact method accurately identifies single or continuous impact loads, with a minimum peak relative error of 0.2%. This study represents a pioneering application of intelligent visual sensing technology in the field of impact load identification. Moreover, the current research introduces a novel approach to address the challenges faced by conventional methods in identifying impact loads. Future research can leverage the groundwork laid by this study to further optimize and expand the proposed method, enhancing its capabilities and fully harnessing its potential to offer advanced solutions in structural health monitoring. [ABSTRACT FROM AUTHOR]

Thin-walled structures that serve as energy absorbers are widely used in the automotive industry, and it is well-known that they deform in a specific way under dynamic loading, forming plastic hinges along the yield line. The dynamic impact of these structures causes various phenomena that affect the formation of folds and, consequently, the dynamic response of the structure. The force-shortening curve, which is based on the unified crush efficiency indicators, is a key factor in determining the dynamic response of the structure. While there have been many studies on energy absorbers under static or quasi-static loading conditions, the effect of changing kinetic energy components (mass and velocity) on the obtained crush efficiency indicators is not as well understood. This article presents the results of experimental tests and nonlinear numerical simulations for eleven different initial conditions of the crashworthiness analysis. The tests showed a significant effect of changing the velocity and mass of the striker on the results obtained. Additionally, the nonlinear effect of the change in the velocity of the tup with respect to the peak force and total efficiency was demonstrated. [ABSTRACT FROM AUTHOR]

This study addresses the challenges in designing packaging to withstand dynamic loads while considering environmental impact and avoiding polymeric materials. It introduces a novel experimental equipment capable of measuring packaging behaviour under corner impacts. The research aims to fill the gap in design tools for non‐flat impact scenarios. By measuring acceleration through dummy products, the study overcomes limitations in cushioning curves. Results offer insights into the dynamic response of packaging systems, aiding in the selection of suitable materials and configurations. Visual analysis enhances understanding of corner protection placement, optimizing energy dissipation. The developed experimental device facilitates rapid data generation, enabling scalable application to corner drop designs, thus serving as a valuable tool in packaging optimization efforts. [ABSTRACT FROM AUTHOR]

This article provides a comprehensive state-of-the-art review of research on bridge deck fatigue under moving wheel loads and compares it to conventional fixed-point pulsating load fatigue. An overview and a brief history of the evolution of this test method from around the world are provided. The effect of key parameters on fatigue life and performance under moving loads are discussed, including loading magnitude and stress ratio, loading footprint, boundary conditions, loading eccentricity, loading frequency, dynamic effect and impact, reinforcement layout, slab thickness, crack control, concrete strength, and environmental exposure conditions. The fatigue accumulation rule and the incremental step (staircase) rolling load method are discussed. Cracking and failure mechanisms in slabs under rolling loads are presented and compared. It is clearly demonstrated that fixed-point pulsating fatigue loads inadequately simulate fatigue damage, stiffness degradation, and cracking patterns induced by rolling loads. For example, one rolling load cycle is shown to be equivalent to 80–1,800 pulsating load cycles. Varying the magnitude of the rolling load (dynamic effect) further reduces the fatigue life. Decreasing the spacing of the transverse rebar and compression reinforcement both can increase susceptibility to crack initiation, potentially reducing fatigue life. Environmental factors, particularly moisture intrusion, drastically reduced fatigue life. A conversion factor of stiffness degradation from pulsating to equivalent rolling load fatigue is proposed. Finally, recommendations for future work in this field are proposed. [ABSTRACT FROM AUTHOR]

Articular cartilage injuries in the knee can lead to post-traumatic osteoarthritis if untreated, causing debilitating problems later in life. Standard surgical treatments fail to ensure long lasting repair of damaged cartilage, often resulting in fibrotic tissue. While there is a vast amount of research into cartilage regeneration, integrating engineered implants with cartilage remains a challenge. As cartilage is a load bearing tissue, it is imperative to evaluate tissue repair strategies and their ability to integrate under mechanical loading. This work established a dynamically loaded ex vivo model of cartilage repair using human cartilage explants. The model was used to assess the efficacy of a stem cell therapy delivered in a bioadhesive hydrogel comprised of photocrosslinkable gelatin methacryloyl (GelMA) and microbial transglutaminase to repair the model defect. Extensive neocartilage production and integration were observed via histology and immunohistochemistry after 28 days chondrogenic culture. Analysis of culture media allowed monitoring of glycosaminoglycan and type II collagen production over time. A mechanical assessment of integration via a push out test showed a 15-fold increase in push out strength over the culture duration. The model was successful in exhibiting robust chondrogenesis with transglutaminase or without, and under both culture conditions. The work also highlights several limitations of ex vivo models and challenges of working with bioreactors that must be overcome to increase their utility. This ex vivo model has the potential to delay the need for costly pre-clinical studies and provide a more nuanced assessment of cartilage repair strategies than is possible in vivo. [ABSTRACT FROM AUTHOR]

Based on the virtual soil pile model, this study investigates the torsional vibration of rock-socketed piles while considering the influence of bottom sediment. First, the bottom sediment is perceived as a virtual soil pile, however, its parameters are still determined according to the characteristics of the sediment. The pile, along with the virtual soil pile, is partitioned vertically into numerous segments in accordance to the stratified characteristics of the rock and soil around the pile. To account for the radial inhomogeneity arising from construction disturbance, the surrounding soil is divided into multiple annular zones characterized by progressively varied soil properties in the radial direction. The governing equations which delineate the soil-pile system under torsional dynamic loading are subsequently formulated and solved to yield an analytical solution for pile complex impedance. After ensuring reliability, the established analytical solution is employed to examine the coupling effect of bottom sediment parameters, pile parameters, and construction disturbance on the torsional vibration characteristics of rock-socketed piles. [ABSTRACT FROM AUTHOR]

The non-uniform distributed pressure of impact wave is usually simplified into concentrated or uniform load equivalently in the optimization design of constrained layer damping structure. However, for the thin-walled structure, it becomes necessary to regard the load as a non-uniform distribution. In this paper, a topology optimization approach is proposed considering the blast load with non-uniform distribution, aiming to unveil its impact on optimization layouts and dynamic responses. Initially, the smoothed particle hydrodynamics (SPH) algorithm is used to obtain the blast pressure what are extracted and integrated into the optimization model. Subsequently, the relative density is regarded as design variable. The construction of material penalty model and the topology optimization model are based on polynomial interpolation scheme (PIS). The sensitivity of objective function is deduced employing an improved adjoint variable method (AVM) to fit the load forms, and the Newmark- β method is used to calculate the dynamic response. The optimization criterion (OC) is adopted to update the design variables. Finally, two numerical examples are used to exhibit the validity and accuracy of the presented methodology. The findings indicate that the distributed form, spread velocity, excited position and excited amplitude of the blast load all exert a notable influence on optimization results and dynamic response. These results underscore the valuable engineering application of this research and introduce a fresh perspective to the challenge of topology optimization under the blast case. [ABSTRACT FROM AUTHOR]

To enhance the impact resistance of hydraulic columns, a theoretical analysis method was employed to develop a dynamic characteristic analysis model for conventional columns under impact loads. This model facilitated the derivation of key parameters such as equivalent stiffness, maximum retraction amount, and impact duration. A fluid-solid coupling model for the conventional column was constructed using finite element and coupled Eulerian-Lagrangian (CEL) methods. Subsequently, numerical simulation results were compared and analyzed against theoretical predictions. Based on this analysis, an energy-absorbing column was designed, and its fluid-solid coupling model was established to investigate its mechanical response under static and dynamic impact loads.The findings indicate that under a static load of 2000 kN, when superimposed with impact loads of 200 kJ, 400 kJ, and 800 kJ respectively, the peak impact forces on energy-absorbing columns are 89.20%, 91.72%, and 98.42% lower than those on normal columns. The yield displacements of energy-absorbing columns increase by 142.26%, 109.15%, and 108.41% compared to normal columns. Energy absorption in energy-absorbing columns is 152.11%, 171.80%, and 145.18% higher than in normal columns. Furthermore, initial velocities of energy-absorbing columns are consistently lower compared to normal columns. After reaching initial velocity, energy-absorbing columns exhibit reduced oscillations due to interactions between the energy absorber, column, and hydraulic fluid system under impact loads. Unlike normal columns, energy-absorbing columns mitigate stress concentration at the column head through interactions between the energy absorber, emulsion, and column. Additionally, the impact resistance time of energy-absorbing columns is 2.19, 1.64, and 1.85 times longer than that of normal columns.Energy-absorbing columns outperform conventional columns across six metrics: peak impact force, column yield displacement, energy absorption, column movement speed, stress distribution, and impact resistance time, demonstrating superior mechanical properties in impact resistance. [ABSTRACT FROM AUTHOR]

Conventional aluminum nitride (AlN) ceramics exhibited insufficient mechanical properties expected from their potential applications in the presence of dynamic loads and intensive stresses caused by thermal shock. In this study, the mechanical properties of AlN ceramics were enhanced by toughening them using AlN whiskers (AlNw) via gel casting followed by low‐temperature sintering at 1650°C. The addition of AlNw simultaneously increased the bending strength, toughness and thermal conductivity of the AlN ceramics. The maximum values of the bending strength, toughness, and thermal conductivity of 9.0 wt% AlNw/AlN were 303.92 MPa, 3.92 MPa·m1/2 and 186.53 W·m−1·K−1, respectively, which were higher than those of the AlN ceramics by 39.93%, 61.31% and, 15.61%, respectively. The AlNw in AlNw/AlN ceramics tightly bonded with the ceramic matrix, leading to two characteristic toughening mechanisms in the ceramics: crack pinning and deflection at irregular grain boundaries caused by doped whiskers, as well as bridging and stress relaxation caused by whiskers incorporated with the grains. Moreover, the one‐dimensional morphology of AlNw can provide a channel for quick photon transport, thereby enhancing the thermal conductivity of AlNw/AlN. [ABSTRACT FROM AUTHOR]

A robust variable step size least mean fourth with a quotient form control scheme (RVSSLMFQ) is implemented for addressing power quality concerns and delivering clean voltage to sensitive loads through a dynamic voltage restorer (DVR). This method estimates the fundamental components from distorted grid voltages, featuring an automated process with adaptive time-varying step sizes and utilizing a quotient structure to reduce mean squared error (MSE) effectively. The suggested control scheme overcomes the stability and performance issues of the least mean fourth (LMF) algorithm by improving convergence and adapting well to varying step sizes. Furthermore, RVSSLMFQ achieves remarkable results with reduced settling time and fewer peak overshoots compared to the least mean square (LMS) and LMF control algorithms. For tuning the load voltage and DC-link voltage proportional-integral (PI) controllers, the improved grey wolf optimization technique (I-GWO) is applied. The results are evaluated through MATLAB simulations. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on the dynamic modeling of distribution power systems with a focus on the integration of renewable energy sources (RESs) for stability analysis. Our research delves into the static and dynamic behavior of distribution systems, emphasizing the need for enhanced load modeling to mitigate planning and operational uncertainties. Using MATLAB/Simulink®, we simulate four distinct study cases characterized by varying load types and levels of distributed generation (DG), particularly solar PV, under both balanced and unbalanced conditions. Our findings highlight the critical role of DG in influencing voltage stability, revealing that deviations in voltage and current during grid imbalances remain within acceptable limits. The study underscores the importance of DG-based inverters in maintaining grid stability through reactive power support and sets the stage for future research on microgrid simulations and battery storage integration to further enhance system stability and performance. [ABSTRACT FROM AUTHOR]

Saturated sand foundations are susceptible to liquefaction under dynamic loads. This can result in roadbed subsidence, flotation of underground structures, and other engineering failures. Compared with the traditional foundation reinforcement technology, enzyme-induced calcium carbonate precipitation technology (EICP) is a green environmental protection reinforcement technology. The EICP technology can use enzymes to induce calcium carbonate to cement soil particles and fill soil pores, thus effectively improving soil strength and inhibiting sand liquefaction damage. The study takes EICP-solidified standard sand as the research object and, through the dynamic triaxial test, analyzes the influence of different confining pressure (σ3) cementation times (CT), cyclic stress ratio (CSR), dry density (ρd), and vibration frequency (f) on dynamic strength characteristics. Then, a modified dynamic strength model of EICP-solidified standard sand was established. The results show that, under the same confining pressure, the required vibration number for failure decreases with the increase in dynamic strength, and the dynamic strength increases with the rise in dry density. At the same number of cyclic vibrations, the greater the confining pressure and cementation times, the greater the dynamic strength. When the cementation times are constant, the dynamic strength of EICP-solidified sand decreases with the increase in the vibration number. When cementation times are 6, the dynamic strength of the specimens with CSR of 0.35 is 25.9% and 32.4% higher than those with CSR of 0.25 and 0.30, respectively. The predicted results show that the model can predict the measured values well, which fully verifies the applicability of the model. The research results can provide a reference for liquefaction prevention in sand foundations. [ABSTRACT FROM AUTHOR]

ABSTRACT The present study explores the influence exerted by various pulse width modulation (PWM) techniques upon harmonic distortion and switching losses of a voltage source inverter. In the context of this inquiry, a generalized algorithm for variable frequency operations, inspired by continuous and discontinuous PWM is outlined in this article. The algorithm is explicitly formulated as a function of fundamental frequency and the load power factor angle with the objective of minimizing total harmonic distortion (THD) and switching losses within a specified frequency range. The algorithm is segmented into various regions of frequency, guided by the theory that each region corresponds to a distinct PWM technique that yields reduced harmonic distortion. In this article, a minimum switching loss algorithm is introduced and implemented using both BCPWM and ABCPWM techniques. The algorithm is specifically designed to minimize switching losses across the entire range of load power factor angles. The integration of switching loss algorithm with the selection of the optimal PWM technique across different frequency ranges results in reduced switching losses and harmonic distortion. This leads to a comprehensive PWM algorithm that efficiently reduces both THD and switching losses during dynamic frequency and load changes. Experimental and theoretical evidences demonstrate the efficacy of the proposed algorithm in attaining minimum harmonic distortion and reduced switching loss operation during variations in fundamental frequency and load. [ABSTRACT FROM AUTHOR]

This paper presents a new semi-analytical approach for the nonlinear vibration and dynamic responses of functionally graded graphene platelet-reinforced composite (FG-GPLRC) panels with complex curvature reinforced by orthogonal and/or inclined stiffeners in the thermal environment resting on the nonlinear viscoelastic foundation with the nonlinearities of von Kármán in the framework of the higher-order shear deformation theory (HSDT). The three curvature types of complexly curved panels are considered to be cylindrical, sinusoid, and parabola panels. Orthogonal and/or inclined stiffeners are modeled utilizing an improved smeared stiffener technique. The stress function form is estimated by applying the like-Galerkin method for complexly curved panels. By applying the Lagrange function and Euler–Lagrange equation, the nonlinear equations of motion of the panels are obtained. The viscous damping effects of the viscoelastic foundation are considered by utilizing the Rayleigh dissipation function. Numerical results are examined utilizing the Runge–Kutta method to acquire the time-deflection curves, and by utilizing the Budiansky–Roth criterion, the critical dynamic buckling loads are determined. From the investigated results, it is possible to evaluate the nonlinear vibration and buckling dynamic responses of three forms of panels with stiffeners. [ABSTRACT FROM AUTHOR]

The stress environments of gob-side roadways (GSRs) are becoming increasingly complex during deep coal mining under thick and hard roofs. This leads to strong strata behaviors, including roadway floor heave, roof subsidence, and even coal bursts. Among them, coal bursts pose the greatest threat to production safety in coal mines. Coal bursts in a GSR strongly correlate with the load characteristics and stress-energy evolution laws of the roadway. This study analyzes the roof structures of double working faces (DWFs) during the initial weighting stage (IWS) and full mining stage (FMS) of gob-side working faces (GSWFs). This study also explores how varying roof structures affect the stability of GSRs. Three-dimensional roof structure models of DWFs and mechanical models of dynamic and static loads superposition on a GSR throughout the IWS and FMS of a GSWF were developed. An analysis identified the primary stress sources affecting the GSR throughout various mining stages of the GSWF. Subsequently, the principle of "three-load" superposition was developed. A novel method was proposed to quantify the stress state in the GSR surrounding rock across different mining stages of the GSWF. The method quantitatively characterizes the load of the GSR surrounding rock. Based on this, the criterion for judging the burst failure of the roadway was established. Numerical simulations are used to analyze the stress-energy evolution laws of the working face, coal pillar, and GSR surrounding rock during the mining process of the GSWF. These findings offer valuable references for studying and preventing coal bursts in GSRs under equivalent geological situations. [ABSTRACT FROM AUTHOR]

The new‐generation manned spacecraft employs a new recovery system of parachutes and airbags. In order to realize the effective cushion of the return capsule airbag, the conversion of the single‐point hanging to the double points for the spacecraft is necessary. In the conversion process, the long hanging rope and the height of the return capsule will cause a large impact and disturbance to the cabin, but the traditional dynamic modeling method is not suitable for those with complex boundary conditions. In order to solve these problems, a finite element model is proposed to analyze the suspension conversion process and simplify the parachute model based on the aerodynamic load dynamic matching control method to analyze the dynamic response characteristics, such as overload, speed, and force of the cabin, quantifying the conditions of the rope in the process. Results are generally consistent with experimental data. This study provides guidance for future optimization work and will greatly support the safe‐return technology of the new‐generation manned spacecraft. [ABSTRACT FROM AUTHOR]

Quantum computing is a rapidly evolving computational means that offers significant speedups for a variety of scientific applications, including machine learning, unsorted database queries, cryptography, and number factorization. Quantum computing holds a significant advantage in its capacity to run quantum algorithms that surpass current classical computer algorithms. However, practical realization of quantum computers remains in its nascent stages, necessitating reliance on classical computation platforms for simulating quantum circuit behavior and developing quantum algorithms. Simulating quantum algorithms presents a formidable challenge due to exponential memory and computation resource demands. In this study, we introduce a novel approach to optimize computational workload distribution during simulation by leveraging Dynamic Load Partitioning (DLP) between host CPUs and GPUs, with the primary aim of reducing resource and computation time requirements. Our method employs a hybrid CPU-GPU platform that divides quantum circuit simulation into two sections, utilizing parallel vector and recursive methods. We conducted our experiments on a cluster of nodes with multiple GPUs to scale qubit simulation and achieve significant speedup over existing simulators. Specifically, our approach demonstrates a remarkable 96X speedup over recursive path-summing on a single GPU and 12.98X speedup over the latest implementation on a multi-node cluster system. Furthermore, our method exhibits energy efficiency, surpassing the state-of-the-art technique by a 55X improvement. These results underscore the effectiveness of the proposed method, especially in leveraging low-cost systems for simulating and processing quantum circuits. [ABSTRACT FROM AUTHOR]

This study focuses on the influence of the pile end soil on the torsional vibration of a pile based on a fictitious soil pile model considering stress diffusion. The pile end soil is simulated as a cone-shaped fictitious soil pile whose parameters remain the same as the soil. The dynamic equilibrium equations for the pile–soil system subjected to torsional dynamic loadings are developed and solved to obtain the corresponding analytical solution. Then, comparisons with other solutions are conducted to verify the reliability of the proposed solution. Finally, parametric analysis results are presented based on the proposed solution to portray the influence of the stress diffusion angle, thickness and shear wave velocity of the pile end soil. [ABSTRACT FROM AUTHOR]

Summary: This article presents a switched‐capacitor‐based 13‐level inverter that exhibits step‐up property. The suggested converter makes use of a single DC source, 12 switches, three capacitors, and two diodes to accomplish the goal of producing a 13‐level output voltage while simultaneously achieving a boosting factor of six. Notably, inherent voltage balancing is attained for a wide variety of load types without the need of complex control methods or additional circuitry. In addition to this, the paper presents a comprehensive study of the power losses that occur across the different components of the converter. Multiple aspects of a topology's performance are taken into account during a comparison analysis with recent topologies that have a single and double DC sources connected to the input. The investigation incorporates simulations with both inductive and resistive loads. In order to validate that the proposed converter is effective, a prototype is built in the laboratory. The practicality of the suggested topology is shown by the collection of experimental result acquired under different loading situations. These findings include dynamic fluctuations in load and modulation indices. [ABSTRACT FROM AUTHOR]

Aiming at the problem of system controller performance failure caused by improperly setting the value of each weighting coefficient of the model predictive control (MPC), a fractional-order MPC strategy with Takagi–Sugeno fuzzy optimization (T–SFO MPC) is proposed for a vehicle active suspension system. Firstly, the fractional-order model predictive control framework for active suspension systems is designed based on a 1/4 vehicle model. Then, we analyze the influence of different weighting coefficients on the suspension performance and introduce the Takagi–Sugeno fuzzy optimization theory to adaptively adjust the weighting coefficients of the fractional-order MPC controller. Finally, the system responses of the T–SFO MPC, traditional MPC, linear quadratic regulator (LQR), and passive suspension control are numerically analyzed under various road conditions. Simulation results show that suspension response with the T–SFO MPC is significantly improved compared with passive suspension control, traditional MPC control, and LQR control, and the weight coefficients of the T–SFO MPC can be adaptively adjusted according to the dynamic changes of suspension response. Compared with passive suspension, the root mean square (RMS) value of the vertical acceleration of the T–SFO MPC under various roads decreased by a maximum of 37.97%, and the RMS value of suspension dynamic deflection and tire dynamic load decreased by a maximum of 32.94% and 37.8%, respectively. These results validate that the proposed control method can achieve coordinated optimization of vehicle comfort and handling stability. [ABSTRACT FROM AUTHOR]

This paper investigates the vibration response of a new part-screw pile composite foundation under moving train loads via a model test method. Based on the acceleration signals of the pile and the surrounding soil, a non-linear fitting method is used to establish the relationship between the dynamic attenuation coefficient and the depth of the foundation. Next, the effect of spatial location and train speed on the pile-soil dynamic interaction is investigated by introducing the pile-soil spectral amplitude ratio δ p − s . In addition, the dynamic susceptibility of the part-screw pile to damage under dynamic train loads is revealed with a wavelet packet energy distribution index E DIS . Afterwards, the cumulative deformation evolution characteristics of screw pile composite foundations under long-term train loading were revealed using the frequency domain integration method. The results of this work reveal that the faster the train runs, the larger the pile-soil spectrum amplitude ratio and the more prominent the 'dynamic concentration effect' of the part-screw pile. The change in cross-section of the part-screw pile results in a sudden change in the vibration energy transmitted from the top of the pile, which makes the variable section of the part-screw pile more likely to cause dynamic damage or even deformation. The cumulative deformation evolution process of soil between part-screw piles under long-term cyclic train loading can be divided into three stages: slow change period, fluctuation rising period and stable deformation period. The research results have important reference significance for the optimization design of high-speed railway part-screw pile composite foundation and the planning of railway running speed. [ABSTRACT FROM AUTHOR]

Spacecraft recovery technology is crucial in the field of aerospace, in which the parachute plays a key role in slowing down the descent speed of the spacecraft and realizing a smooth landing. In order to construct a dynamically adjustable parachute deployment strategy, it is necessary to measure the parachute dynamic load accurately in real-time. However, the existing sensor measurement scheme makes it difficult to meet the measurement requirements due to its large structure and complex wiring. In order to meet the current demand for real-time measurement of parachute cords dynamic load, a miniature measuring instrument is designed. According to the function and technical requirements of the miniature measuring instrument, the hardware modules of the acquisition system are selected and designed, and the integration debugging and performance optimization of the microcontroller module, A/D sampling module, signal acquisition circuit, and power supply module are carried out. The software of the parachute cords tension acquisition system based on the miniature measuring instrument is developed. The Load Cell is modeled by using SolidWorks 2022 and statically analyzed by using Ansys 2022 R1 Workbench finite element analysis software. Then the final structure of the Load Cell and the pasting position of the strain gauge are determined through the results analysis as well as experimental verification. The hardware module of the signal acquisition system for the miniature measuring instrument is then encapsulated. The force value of the miniature measuring instrument is calibrated and tested many times by using the microcomputer-controlled electronic universal testing machine. The experimental results show that the designed miniature measuring instrument has accurate data, strong stability, and good real-time performance, which meets the demand for real-time accurate measurement of miniature measuring instruments, and can provide reliable data for parachute cords parameter validation and stepless unfolding design. [ABSTRACT FROM AUTHOR]

The surrounding rock stiffness has a significant effect on the impact mechanical properties of rockbolts. In order to study the influence of radial stiffness of surrounding rock on the dynamic characteristics of the end-anchored rockbolt, numerical simulations of drop weight impact tests on the end-anchored rockbolt were conducted using finite element method. The simulation results show that the larger the radial stiffness of the surrounding rock, the larger the value of the absorbed impact energy of end-anchored rockbolt. However, there is an upper limit to the effect of radial stiffness on the dynamic behavior of end-anchored rockbolt, i.e., the value of absorbed impact energy tends to be stabilized when the radial stiffness exceeds 2.91 GPa/mm. In the impact simulation, the fracture position of the bolt bar is affected by both radial stiffness and impact energy. The greater the radial stiffness of the surrounding rock, the further the fracture location is away from the anchorage end. The larger the impact energy is, the closer the fracture location is to the anchorage end. It is important to study and determine the range of fracture location of anchor rods to develop new types of anchor rods and to design the support scheme for the surrounding rock under dynamic loading. Finally, due to the linkage between numerical simulation and indoor tests, the effect of steel pipe wall thickness on the upper and lower limits of the results also provides a theoretical basis for the rationalization of the design of steel pipe wall thickness. The study of dynamic impact fracture location of bolt bar is of great significance for the development and design of new types of rockbolt under dynamic loading. [ABSTRACT FROM AUTHOR]

Shallow resources are becoming increasingly depleted, deep resource exploration has become a global strategy. The design and testing of deep in-situ core samples are prerequisites for exploring deep resources; however, no in-situ condition-preserved coring and testing techniques and tools have been reported yet. Here, the first deep in-situ conditionpreserved coring system (with the preservation of pressure, temperature, substance, light, and moisture) was developed that considers the effects of high water pressure and formation dynamic loads, along with an in-situ condition-preserved testing system. A pressurepreserved controller was designed, achieving the ultimate capacity of 140 MPa and 150 ℃. A temperature-preserved coring system combining active heating and passive insulation was constructed, realizing temperature preservation from room temperature to 150 ℃. Three generations of film-formation principles and methods were designed, achieving an excellent quality preserved rate, moisture preserved rate, and visible light barrier rate. Moreover, a deep in-situ condition-preserved coring system, and a simulated coring platform for large cores under in-situ environments was fabricated. A non-contact testing system was derived to cut and prepare specimens under in-situ environment and to perform non-contact non-destructive testing and true triaxial testing. The research findings can be successfully applied to deep coal and gas development, deep oil and gas resources assessment, and deep-sea sediment prospecting, achieving excellent application outcomes. This study provides important theoretical, technical and hardware support for deep in-situ rock physics and mechanics research and deep resource exploitation. [ABSTRACT FROM AUTHOR]

Expanded polystyrene (EPS) particle-based lightweight soil, which is a type of lightweight filler, is mainly used in road engineering. The stability of subgrades under dynamic loading is attracting increased research attention. The traditional method for studying the dynamic strength characteristics of soils is dynamic triaxial testing, and the discrete element simulation of lightweight soils under cyclic load has rarely been considered. To study the meso-mechanisms of the dynamic failure processes of EPS particle lightweight soils, a discrete element numerical model is established using the particle flow code (PFC) software. The contact force, displacement field, and velocity field of lightweight soil under different cumulative compressive strains are studied. The results show that the hysteresis curves of lightweight soil present characteristics of strain accumulation, which reflect the cyclic effects of the dynamic load. When the confining pressure increases, the contact force of the particles also increases. The confining pressure can restrain the motion of the particle system and increase the dynamic strength of the sample. When the confining pressure is held constant, an increase in compressive strain causes minimal change in the contact force between soil particles. However, the contact force between the EPS particles decreases, and their displacement direction points vertically toward the center of the sample. Under an increase in compressive strain, the velocity direction of the particle system changes from a random distribution and points vertically toward the center of the sample. When the compressive strain is 5%, the number of particles deflected in the particle velocity direction increases significantly, and the cumulative rate of deformation in the lightweight soil accelerates. Therefore, it is feasible to use 5% compressive strain as the dynamic strength standard for lightweight soil. Discrete element methods provide a new approach toward the dynamic performance evaluation of lightweight soil subgrades. [ABSTRACT FROM AUTHOR]

Considering the importance of understanding the propagation of transient waves in the piezomagnetic solids, the thermal effect on the transient behavior of a piezomagnetic half-space subjected to dynamic anti-plane load is investigated analytically in this paper. Using one-sided, two-sided Laplace transformation and Cagniard–de Hoop (CH) technique, an efficient and accurate analytical derivation for the solution of the anti-plane displacement, shear stress, magnetic potential, and induction in Laplace domain is presented. The study shows that the thermal stresses developed in x -axis and y -axis directions have significant influence on the transient response of the half-space. The magnetic induction B x increases obviously when the thermal stress is applied in x -axis direction, while it decreases when the thermal stress is applied in y -axis direction. Approaching time of magnetic induction B x and B y will become longer with higher thermal stress in x -axis direction. With the growth of the thermal stress in x -direction, contribution from the electromagnetic–elastic head (EH) wave increases, while the contribution from the shear elastic (SE) wave and the static value of shear stress decrease. [ABSTRACT FROM AUTHOR]

The integration of alternative energy sources, storage systems, and modern loads into the distribution grid is complicating its operation and maintenance. Variability in individual generation and consumption elements dynamically affects voltage profiles, which in turn undermines efficiency and power quality. This study proposes to address this dynamical variability using an online reconfiguration approach that involves opening and closing switches to modify the grid's topology and adjust voltage levels in response to load/generation variations. Other grid optimization techniques, based on reconfiguration, typically focus on static, fully instrumented grids with predictable parameters and homogeneous changes, aiming to minimize power losses but overlooking the dynamics of variable grid elements. This study proposes a testing approach that is dependent on the estimated transient status of the grid only using a limited number of measurement units and considering the individual‐stochastic variations of loads and generators. The proposed approach was tested on the IEEE 33‐bus test feeder with up to five varying distributed generators. The results confirm that the algorithm consistently finds a reconfiguration alternative that could enhance system efficiency and voltage profiles, even in the face of dynamic load/generator behavior, demonstrating its effectiveness and online adaptability for grid operation and management tasks. [ABSTRACT FROM AUTHOR]

Accurate measurement of dynamic behaviors of rocks under complex static stress conditions can provide valuable insight into the design of underground rock engineering. The end friction between the specimen and the loading device becomes more severe in the measurement of rocks under static stress conditions because the end friction effect may be amplified by the static stress on the specimen ends. However, there are few studies on quantifying the end friction effect on the dynamic test for deep rocks. Thus, three groups of Fangshan marble (FM) specimens were prepared in this study. Specimen S1 and S3 are cylinders, and specimen S2 is a tube. The diameter of specimen S1 is the same as the outer diameter of specimen S2, and the cross-sectional area of specimen S3 is the same as that of specimen S2. The dynamic and total uniaxial compressive strength (UCS) of three types of specimens under various preloads were measured using the modified SHPB system. The splitting failure can be observed for these three types of specimens, and the center portion of specimen S1 was relatively intact, which can be attributed to the end friction effect. The end friction inhibits crack propagation, and thus the total UCS of rocks continuously increases with the axial preload. The increment of total UCS of FM at the same loading rate in terms of the preload differs for these three types of specimens due to the end friction effect. The difference in the dynamic UCS between lubricated and dry conditions is slight when the preload is higher, but the lubrication effect is more severe when the preload is lower. A formula is proposed to quantitatively assess the end friction effect and predict the total UCS of rocks under various dynamic loading rates and static axial preloads. Appropriate specimen geometries are suggested to ensure the precision of measurement of the dynamic UCS of deep rocks. Highlights: The total UCS of rocks increases with the axial preload due to the inhibition of microcrack propagation. The effect of lubrication at different preloads is analyzed. A formula is proposed to quantitatively assess the end friction effect. The total UCS of rocks under various dynamic and static loadings can be predicted. Appropriate specimen geometry is recommended to minimize the end friction effect. [ABSTRACT FROM AUTHOR]

A promising solution to reduce energy usage and mitigate the wear of drilling and comminution tools during mining operations involves inducing vibrations within the piezoelectric phases dispersed in the structure of rocks using alternating current (AC). This paper presents experimental evidence of AC-induced weakening of Kuru granite, manifested as improvements in rock drillability and reductions of strength. Sievers' J-miniature drill tests were used to assess surface drillability. The impact of AC treatment on the quasi-static strength of granite was assessed via three-point bending and indirect tension Brazilian disk tests. The influence of AC treatment on the dynamic tensile strength of the rock was determined using split Hopkinson bar tests, with the fragmentation process captured using in situ ultra-fast synchrotron X-ray phase contrast imaging. The quasi-static tests revealed no reduction in rock strength after the AC treatment. In contrast, reductions of 25% in hardness and 18% in dynamic tensile strength were observed. Fragmentation patterns differed between treated and non-treated rocks, with treated specimens exhibiting reduced macrocrack formation during loading. Highlights: Diverse experiments confirm that alternating current excitations weaken Granite. Sievers' J-tests evidenced enhanced drillability of Granite after the alternating current treatment. Exposure to alternating currents decreased the tensile strength of Granite in dynamic Brazilian disc experiments. Treated Brazilian disc specimens showed lower energy absorption during dynamic loading. Synchrotron X-ray phase contrast images revealed reduced crack branching of treated granite specimens during dynamic loading. [ABSTRACT FROM AUTHOR]

Accelerating performance and braking performance are the core performance of a vehicle, and tire load analysis is a prerequisite for performance studying. A calculation and correction method of dynamic tire loads is proposed in this paper. First, the numerical and experimental models of tire dynamic load identification are established, by measuring the acceleration signals at different positions of the steering knuckle arm, the tire deformation in three directions is inversely calculated. Second, the longitudinal force, lateral force and vertical force of the tire are estimated according to the tire stiffness and deformation. Finally, the tire loads are corrected by data filtering and tire stiffness adjustment. The results show that the average agreement between the calculated load and the test load is more than 90%. The calculation and correction method can provide a theoretical basis and reference for analyzing the dynamic change characteristics of tire load. [ABSTRACT FROM AUTHOR]

A rhombus-nested compliant amplification mechanism is proposed for versatile usages of precision actuators and force sensors with an easy tuning of stiffness. Such a monolithically planar rhombus-nested compliant mechanism has the dual functions of two-stage displacement or force amplification by changing the input and output ports. It features a large ratio of inter-stage stiffness, thus resulting in an enhanced amplification ratio, load capacity and dynamic bandwidth. The geometrically nonlinear analytical equations of displacement amplification ratio and input stiffness are derived in the presence of pronounced axially-loaded stiffening and kinematic-arching effects based on the beam constraint model. It allows an insightful evaluation of geometrically nonlinear deformation behaviors sensitive to structural dimensions in a parametric way. Insights into geometrically nonlinear behaviors in the case of large-stroke and axially-loaded motions are discussed as well. A proof-of-concept prototype with embedded piezoelectric stacks is fabricated with the dimensions of 74mm × 60mm × 10 mm. The dual functions of precision actuator with amplified motion strokes and force sensor with enhanced sensitivity are experimentally demonstrated. [Display omitted] • A monolithically rhombus-nested compliant amplification mechanism is designed. • Geometrically nonlinear analytical model of amplification ratio is derived. • The dual functions of a precision actuator and force sensor are demonstrated. [ABSTRACT FROM AUTHOR]

The present investigation includes experimental and ANN-based intelligent modeling to explore the dynamic interference effect of closely positioned vibrating foundations placed on unreinforced and geogrid-reinforced soil beds. Large-scale field block vibration tests are conducted on isolated and interacting block footings placed on prepared foundation beds at IIT Kanpur, India. The dynamic interaction of various combinations of two-footing assemblies is examined where one footing (active footing) is excited with dynamic loadings, and the other (passive footing) carries static loadings. The tests involve three eccentric force settings for four distinct footing combinations at different clear spacings and reinforcement conditions. The responses of both footings are recorded at different loading frequencies. The interaction effect is presented in terms of the transmission ratio plotted against the frequency ratio. Additionally, an Artificial Neural Network (ANN) model is developed using the recorded field datasets to anticipate the dynamic interference effect. The predicted outcomes of the ANN model demonstrate promising agreement with the experimental findings reported in the literature, indicating the reliability and robustness of the intelligent model. • Dynamic interaction between closely spaced footings is explored for unreinforced and geogrid-reinforced soil beds. • Effect of footing size, dynamic force level and spacing between footings is examined. • Efficacy of geogrid layers in reducing interaction between footings is observed. • An Artificial Neural Network (ANN) model is developed to predict the dynamic interaction effect. [ABSTRACT FROM AUTHOR]

Self-compacting concrete (SCC) is widely used in reinforced concrete buildings, owing to its ability to consolidate by weight and its lack of requirement for external vibration. Reinforced concrete buildings can be subjected to high strain rate loading during the early days of construction or in their service life. Thus, it is critical to understand the behaviour of concrete under high strain rate loadings at different ages. Minimal studies have previously focused on the early-age behaviour of concrete under high strain rates. This study tries to fill this gap. It focuses on the behaviour of M40 grade SCC under three levels of strain rate loading at ages of 1, 3, 7, 14 and 28 d. The split-Hopkinson pressure bar (SHPB) was used to test 45 SCC specimens of diameter 100 m and thickness 50 mm at high strain rates, ranging from 30 s−1 to 110 s−1, and the determined compressive strength, peak strain and elastic modulus results are compared with quasistatic test results of SCC specimens. The dynamic increase factor (DIF) determined in the SHPB experiment is compared with the CEB-fib code model. The results indicate that the DIF reduces as the concrete's strength and age increase. [ABSTRACT FROM AUTHOR]

Seismic retrofitting of existing bridges has been in practice for years to meet the stringent seismic requirements set forward by revised design codes. For retrofitting, however, bridge piers are often prioritized while less attention is given to the bridge foundations, which are equally prone to damage under seismic loadings. The current work presents a series of experimental studies in assessing the performance of 2 × 2 pile groups reinforced with micropiles in terms of head-level stiffness and damping under low-to-high levels of static and dynamic loadings, encompassing the influence of loading-induced soil nonlinearity. Practical micropiles inclinations of 0°, 5°, and 10° with respect to the vertical are studied. Experimental results reveal that the head-level stiffnesses of pile groups reinforced with micropiles, contrary to the general expectations, become smaller than the pile group without micropiles at higher levels of applied loading. To elucidate the governing mechanism for such experimentally obtained results, three-dimensional nonlinear finite-element analyses were carried out. Results from the numerical analyses support the experimental results, suggesting that the presence of micropiles may not always increase the head-level stiffness of soil–foundation systems, particularly at higher levels of applied loading where the soil nonlinearity generated at the vicinity of piles and micropiles governs the overall head-level stiffnesses. [ABSTRACT FROM AUTHOR]