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This paper presents a comprehensive analysis of the influence of rotary table velocity, weight-on-bit, and viscous damping on the drill string stick–slip vibration. The analysis allows for studying the qualitative and quantitative variation of the dynamic response of the drill pipes and drill collars/bit. To achieve this goal, a robust and practical finite element (FE) model of the full-scaled drill string was developed based on a velocity-weakening formulation of the nonlinear bit–rock interaction. A detailed investigation of damping parameters was carried out. The performance of the developed model was verified through comparisons with a lumped-parameter model and a field test example. Parametric studies on the stick–slip response of the entire drill string under different field operational conditions were conducted. The dynamical time series of the system response were analyzed in terms of the phase planes, response spectra, and descriptive statistics of the drill pipes and drill collars. The findings of the study revealed that for a realistic drill string geometry, the angular velocity (i.e., mean, peak-to-peak amplitude, and standard deviation) and dominant frequency of self-excited torsional stick–slip oscillations along the drill pipes and drill collars/bit are mainly governed by the rotary table velocity. Furthermore, it was shown that the contribution of higher harmonics in the torsional stick–slip response of the drill pipes is more substantial than the drill collars/bit.

In recent decades, reinforced concrete (RC) shear walls have been one of the best structural solutions to resist lateral load in high-rise buildings. Shear wall openings are essential for preparations and architectural requirements, which weaken the wall, reducing bearing capacity, energy absorption, and stiffness while also causing stress concentrations. This paper presents a comprehensive finite element (FE) investigation of the behavior and performance of RC shear walls with openings and subjected to lateral loads. The study aims to evaluate the influence of various parameters, such as opening location, size, wall aspect ratio, axial load, and concrete strength, which affect the performance of shear walls. FE models were developed to simulate the seismic response of RC shear walls under the combined effect of constant axial and lateral loads. The obtained results from the FE model showed a successful validation using the experimental data available in the literature. The FE analysis results demonstrate that the inclusion of lower openings leads to a 25% decrease in the bearing capacity of the wall when compared to the upper openings. Moreover, it was observed that augmenting the sizes of the openings and the aspect ratios of the wall resulted in declines in the strength, stiffness, and energy absorption capacity of the wall while simultaneously enhancing the ductility and displacement of the RC shear walls.

Adult-acquired flatfoot has been considered to arise from tibialis posterior tendon deficiency. Recent evidence shows that arch stability is mainly maintained by structures such as plantar fascia and spring ligament. The dysfunction of these ’passive’ stabilizers results in loss of arch integrity that causes forefoot pronation and reactive tendon overload, especially in the tibialis posterior tendon and peroneus longus tendon. The peroneus longus tendon (PLT) spans several midfoot joints and overloads with arch lengthening. The biomechanical stress/changes that occurs in this tendon are not well recognized. This study evaluates the biomechanical consequences that fusions have on peroneus longus tendon stresses in soft-tissue deficiencies associated with flatfoot deformity. A complete computational human foot model was used to simulate different scenarios related to the flatfoot deformity and associated common midfoot/hindfoot fusions, to quantify the biomechanical changes in the peroneus longus tendon. The results showed that the stress of the peroneus longus tendon is especially affected by the fusion of hindfoot joints and depends on the soft tissue types that fail, causal in generating the flatfoot. These results could be useful to surgeons when evaluating the causes of flatfoot and the secondary effects of surgical treatments on tissues such as the peroneus longus tendon.

This paper presents the concept of periodic marine risers, which is investigated in a comprehensive theoretical manner to establish tools for the design and prediction of the performance characteristics of this class of risers. The presented concept of periodic risers introduces an optimally placed and designed array of periodic inserts that reinforce the conventional riser to, on the one hand, enhance its elastic instability threshold to internal flows and, on the other hand, introduce stop/pass band characteristics that can trap the vortex shedding excitations in order to mitigate their effects. Such a concept has not been investigated in the literature. The effectiveness of the concept is investigated and demonstrated theoretically by modeling the dynamics of these risers using finite element analysis and developing their instability threshold to internal flows, as well as their bandgap characteristics by extracting the eigenvalues of the associated transfer matrices. Comparisons are established between the performance characteristics of these periodic risers and conventional risers to demonstrate the merits and limitations of the proposed concept.

Thin-walled structures are extensively utilized in construction because of their lightweight nature and excellent energy absorption efficiency, especially under dynamic loads. Improving the energy-absorbing performance of thin-walled structures by inspiring natural multi-cell designs is a sufficient approach. This paper investigates the energy-absorbing characteristics of variable novel cross-section designs of thin-walled structures subjected to oblique impact loading. Straight and tapered types with seven cross-sectional designs of novel thin-walled structures were studied. The nonlinear ABAQUS/Explicit software 6.13 version was implemented to analyze the crashworthiness behaviors for the proposed variable cross-section designs under different loading angles. The crushing behaviors of the proposed thin-walled structures were examined for various wall thicknesses of 0.5 mm, 1.5 mm, and 2.5 mm and impact loading angles of 0°, 15°, 30°, and 45°. It was determined that the energy-absorbing characteristics of novel thin-walled structures can be efficiently controlled by varying two geometries and seven cross-section designs. A multi-criteria decision-making method (MCDM) using a complex proportional assessment method (COPRAS) was performed to select the optimum thin-walled structures with cross-section designs. It was shown that a tapered square thin-walled structure with 2.5 mm thickness had the best crashworthiness performances with energy absorption (EA) of 11.01 kJ and specific energy absorption (SEA) of 20.32 kJ/kg under a 30° impact angle. Moreover, the results indicated that the EA of the thin-walled structure decreased with the increase in the impact loading angle. In addition, with the increase in the impact loading angle, the peak crushing force (PCF) decreased and reflected the reduction in energy absorbed at a larger angle. The MCDM method in conjunction with the COPRAS method is proposed, it provides valuable insights for safer and more resilient building construction.

The increasing use of large glass surfaces in modern architecture requires robust adhesive solutions that balance aesthetic appeal with structural resilience, particularly in timber–glass applications. This study examines the influence of primer treatments on the shear performance of timber–glass adhesive joints, employing a combination of experimental testing and simulation techniques. Double-lap shear tests with epoxy adhesives assess the impact of various surface treatments on joint stiffness, shear stress distribution, and deformation. Additionally, a finite element model is developed to simulate joint behavior, evaluate failure modes, and analyze displacement patterns. Results indicate that primer applications notably enhance structural integrity by reducing displacement and increasing joint stability, thereby supporting more durable timber–glass assemblies. These findings offer valuable insights for advancing adhesive technologies in architectural components, enabling a closer alignment between structural performance and design innovation in timber–glass systems.

This paper investigated the hysteresis performance of multi-story Y-shaped eccentrically bare braced steel frames with block slit dampers (BSDs). After validating existing models through finite element (FE) analysis, an FE model of Y-shaped eccentrically bare braced steel frames (YEBFs) with BSD (BSD-YEBFs) was established. The influences of different types of BSDs on the hysteresis performance of YEBFs were subsequently analysed, as were the seismic performances of YEBFs with BSD (BSDF) and traditional Y-shaped eccentrically bare braced steel frames (TEBF) under cyclic loading, including the stress failure mode, hysteresis curve, stiffness, strength, and energy dissipation capacity. The results showed that: (1) compared with those of BASE-Y, the ductility coefficients of YEBFs with one level BSD (BSD-1) and two level BSD (BSD-2) increased by 59.57% and 39.47%, respectively, and the lateral bearing capacity decreased by 3.26% and 2.78%, respectively. (2) Compared with those of TEBF, the yield bearing capacity and ultimate bearing capacity of BSDF increased by 3.13% and 11.12%, respectively, and the ductility coefficient increased by 56.7%. Moreover, BSDF possesses higher initial stiffness and more sustained energy dissipation capabilities.

Degenerative cervical myelopathy (DCM) is characterized by progressive neurological dysfunction, yet the contribution of intramedullary stress and strain during neck motion remains unclear. This study used patient-specific finite element models (FEMs) of the cervical spine and spinal cord to examine the relationship between spinal cord biomechanics and neurological dysfunction. Twenty DCM patients (mean age 62.7 ± 11.6 years; thirteen females) underwent pre-surgical MRI-based modeling to quantify von Mises stress and maximum principal strains at the level of maximum spinal cord compression during simulated neck flexion and extension. Pre-surgical functional assessments included hand sensation, dexterity, and balance. During flexion, the mean intramedullary stress and strain at the level of maximum compression were 7.6 ± 3.7 kPa and 4.3 ± 2.0%, respectively. Increased intramedullary strain during flexion correlated with decreased right-hand sensation (r = −0.58, p = 0.014), impaired right-hand dexterity (r = −0.50, p = 0.048), and prolonged dexterity time (r = 0.52, p = 0.039). Similar correlations were observed with intramedullary stress. Patients with severe DCM exhibited significantly greater stress during flexion than those with mild/moderate disease (p = 0.03). These findings underscore the impact of dynamic spinal cord biomechanics on neurological dysfunction and support their potential utility in improving DCM diagnosis and management.

Steel I-beams may be subject to deviation from their normal path towards the lateral direction due to obstacles along their axis line. This deviation in the lateral direction, i.e., the out-of-plane distance, affects the behavior of the steel beams and may reduce their ultimate capacity. To obtain this effect, finite element modeling (FEM) was used to model these beams with and without an out-of-plane distance at the mid-span beam length with several different variables. These variables were the out-of-plane distance, cross-section dimensions, beam length, and steel yield stress. The reliability of using FEM simulation was confirmed by comparing the experimental test results of 25 available steel beams in previous studies. The results indicate the high accuracy of the simulation of this beam in terms of ultimate capacity, structural behavior, and deformation patterns. After verifying the results, 116 broad-flange I-beam (BFIB) steel beams with different out-of-plane distances were modeled. The results showed that using an out-of-plane distance equal to the flange width of the BFIB-300 cross-section caused a 60% decrease in the ultimate capacity. The reduction ratios in the ultimate moment capacity in out-of-plane steel beams were directly proportional to the out-of-plane distance, cross-sectional dimensions, and steel yield stress, while the beam length had no effect. Failure in beams containing an out-of-plane distance occurs as a result of a global buckling in the upper flange, which contains tensile stresses at the outer edge and compressive stresses at the inner edge, with stress concentration occurring at the point of contact of the out-of-plane part with the main beam. The prediction results of the design codes were compared with the results of experimental tests and the FEM analysis of the beams with and without out-of-plane distances. For all the beams with out-of-plane distances, all the design codes were unable to predict this ultimate capacity.

This research investigates the seismic behavior of rigid and flexible cylindrical steel tanks, focusing on tanks with an open top and fully anchored at the base. The primary objective is to evaluate the hydrodynamic pressures exerted by the fluid on the tank walls during seismic excitation. Three widely recognized design approaches—New Zealand NZSEE recommendations, European code UNI EN 1998-4:2006 (CEN, 2006), and American Water Works Association AWWA D100-05 standard (ANSI/AWWA, 2005)—were implemented and compared with high-definition finite element models and then validated against the experimental results. Nonlinear fluid–structure interaction (FSI) was modeled using an Arbitrary Lagrangian–Eulerian (ALE) formulation with the Navier–Stokes equations governing the fluid motion and material and geometric nonlinearities considered in the tank walls. Parametric analyses were conducted to investigate the impact of tank geometry, specifically height-to-radius and radius-to-thickness ratios, on seismic response, identifying a transition between rigid and flexible behavior. The study also examined the influence of seismic input using a set of ten displacement spectrum-compatible ground motions. The findings contribute to a better understanding of the seismic resilience of cylindrical steel tanks, offering valuable insights for improving design standards and safety in earthquake-prone regions where these systems may abound.

Transfer learning techniques for structural health monitoring in bridge-type structures are investigated, focusing on model generalizability and domain adaptation challenges. Finite element models of bridge-type structures with varying geometry were simulated using the OpenSeesPy platform. Different levels of damage states were introduced at the midspans of these models, and Gaussian-based load time histories were applied at mid-span for dynamic time-history analysis to calculate acceleration data. Then, this acceleration time-history series was transformed into grayscale images, serving as inputs for a Convolutional Neural Network developed to detect and classify structural damage states. Initially, it was trained and tested on datasets derived from a Single-Source Domain structure, achieving perfect accuracy (1.0) in a ten-label multi-class classification task. However, this accuracy significantly decreased when the model was sequentially tested on structures with different geometry without retraining. To address this challenge, it is proposed that transfer learning be employed via feature extraction and joint training. The model showed a reduction in accuracy percentage when adapting from a Single-Source Domain to Multiple-Target Domains, revealing potential issues with non-homogeneous data distribution and catastrophic forgetting. Conversely, joint training, which involves training on all datasets except the specific Target Domain, generated a generalized network that effectively mitigated these issues and maintained high accuracy in predicting unseen class labels. This study highlights the integration of simulation data into the Deep Learning-based SHM framework, demonstrating that a generalized model created via Joint Learning utilizing FEM can potentially reduce the consequences of modeling errors and operational uncertainties unavoidable in real-world applications.

AISI 304 is widely regarded as the most common austenitic stainless steel and is utilized in various household and industrial applications, including food handling equipment, machinery components, and heat exchangers. Its popularity stems from its excellent mechanical properties, corrosion resistance, and ease of manufacturing. Given its diverse applications, it is crucial to study the microstructural evolution and mechanical properties of the welded zone, especially considering the potential for weld decay during fusion welding. In this context, two critical thermal-dependent factors for ensuring high-quality welds are grain growth and hardness variation in the heat-affected zone (HAZ) during the welding process. This paper presents an innovative finite element (FE) model developed to analyze the grain growth and hardness reduction that occur in the HAZ during plasma arc welding (PAW) of AISI 304 steel for solid expansion tube (SET) technology. Using the commercial FE software SFTC DEFORM-3D™, a user subroutine was created that integrates a physics-based model with the Hall–Petch (H-P) equation to predict changes in grain size and hardness. This study introduces a comprehensive numerical model, encompassing the user subroutine, heat source fitting, and geometry, which accurately predicts the thermal phenomena associated with grain coarsening and hardness reduction in the HAZ during the welding of austenitic stainless steel. The results from the numerical model, including the customized user routines, show good agreement with experimental data, leading to a maximum error prediction of 10 HV in hardness, 30 µm in grain size, and 10% in HAZ extension.

Ultrasound is an excellent way to acquire data that reveal useful information about systems operating in harsh environments, which may include elevated temperature, ionizing radiation, and aggressive chemicals. The effects of harsh environments on piezoelectric materials have been studied in much more depth than the other aspects of ultrasonic transducers used in pulse-echo mode. Therefore, finite element simulations and laboratory experiments are used to demonstrate the unique characteristics of pulse-echo immersion testing. Using an aluminum nitride piezoelectric element mounted on a vessel wall, characteristics associated with electrode thickness, couplant, backing material, and an acoustic matching layer are investigated. Considering a wave path through a vessel wall and into a fluid containing a target, when the travel distance in the fluid is relatively short, it can be difficult to discern the target echo from the reverberations in the vessel wall. When an acoustic matching layer between the vessel wall and the fluid does not suffice, a simple subtractive signal-processing method can minimize the reverberations, leaving just the target echoes of interest. Simulations and experiments demonstrate that sufficient target echoes are detected to determine the time of flight. Furthermore, a simple disc-like surface anomaly on the target is detectable.

The purpose of this study was to determine the effect of fiber reinforcement materials on the magnitude of stresses in a critical part of the maxillary denture base under thermal and occlusal load. Thermal stress analyses of the models were carried out using the finite element method. The models consisted of bone, soft tissue, interface gap, and maxillary dentures with and without reinforcements. A concentrated occlusal load of 230 N was applied bilaterally on the molar teeth. A 36 °C reference and 0 °C, 36 °C, and 70 °C variable ambient temperatures were applied to the models. CrCo, unidirectional and woven carbon/epoxy, unidirectional and woven glass/epoxy, and unidirectional and woven Kevlar/epoxy were used as reinforcing materials in the maxillary denture base made of PMMA (polymethyl methacrylate). Stress distributions on the maxillary denture’s midline and lateral line direction were evaluated. Maximum stresses in the incisal notch and the labial frenal notch of the maxillary denture were determined. Failure analysis of reinforcement materials used in maxillary dentures was carried out using the Tsai-Wu index criterion. The results obtained show that the thermal properties of reinforcement materials should be considered as an important criterion in their selection.

The use of carbon fiber reinforced polymer (CFRP) strands as prestressed reinforcement in prestressed concrete (PC) structures offers an effective solution to the corrosion issues associated with prestressed steel strands. In this study, the flexural behavior of PC beams reinforced with prestressed CFRP strands and non-prestressed steel rebars was investigated using finite element modeling (FEM) and artificial neural network (ANN) methods. First, three-dimensional nonlinear FE models were developed. The FE results indicated that the predicted failure mode, load-deflection curve, and ultimate load agreed well with the previous test results. Variations in prestress level, concrete strength, and steel reinforcement ratio shifted the failure mode from concrete crushing to CFRP strand fracture. While the ultimate load generally increased with a higher prestressed level, an excessively high prestress level reduced the ultimate load due to premature fracture of CFRP strands. An increase in concrete strength and steel reinforcement ratio also contributed to a rise in the ultimate load. Subsequently, the verified FE models were utilized to create a database for training the back propagation ANN (BP-ANN) model. The ultimate moments of the experimental specimens were predicted using the trained model. The results showed the correlation coefficients for both the training and test datasets were approximately 0.99, and the maximum error between the predicted and test ultimate moments was around 8%, demonstrating that the BP-ANN method is an effective tool for accurately predicting the ultimate capacity of this type of PC beam.

The synchronous construction of the pylon and cables of a cable-stayed bridge without backstays has the characteristics of a short construction period and reduced support costs. However, it also increases the difficulty of construction control, making the reasonable completion state of the bridge more complex. To investigate the impact of various load parameters on the structural state of a cable-stayed bridge without backstays during the synchronous construction process, and to ensure a rational final bridge state, this study proposes an assessment framework for evaluating the internal forces of the bridge. The framework initially uses the response surface method to establish explicit equations relating the control indicators of the bridge’s final state to various load parameters. Subsequently, through sensitivity analysis, the degree of influence of each load parameter on the structural response of the cable-stayed bridge without backstays is examined. The most sensitive factors are identified to create a bridge parameter influence library, which helps reduce computational costs. Based on this, a method for controlling construction errors and predicting cable forces is proposed. This method utilizes the pre-established bridge parameter influence library, combined with the internal force state of the bridge at the current construction stage, to accurately predict the tension force of the stay cables in the subsequent stage, thereby ensuring a rational final bridge state. The framework is ultimately validated through a case study of the Longgun River Bridge to assess its rationality and effectiveness.

This manuscript addresses the issue of electromagnetic radiation interference experienced by secondary equipment in ultra-high voltage (UHV) fixed series capacitors (FSCs) under electromagnetic transient overvoltage conditions, which cannot be easily determined. To tackle this, a simulation and analysis method for the electromagnetic interference characteristics of secondary equipment is proposed. First, a primary system simulation model of UHV FSC is established, including modeling the platform’s multi-conductor system. The electromagnetic transient overvoltage signals between the low-voltage busbar and the high-potential platform are then simulated and analyzed under two conditions: spark gap triggering and disconnector operation. Next, a finite element model of secondary equipment is created to simulate and analyze the electric field distribution of different materials in the area of the measuring box. The shielding effectiveness of the measuring box is calculated using the overvoltage signals at the measuring box location as excitation. This method allows for the simulation of the electric field distribution in the measuring box area for different materials and calculates the shielding efficiency of the measuring box. It effectively simulates the complex electromagnetic environment of secondary equipment, assesses the electromagnetic shielding efficiency of the measuring box, and provides a theoretical basis for analyzing and improving the anti-interference characteristics of the measuring box.

This paper presents a finite element (FE) model of reinforced concrete two-way slab strengthened using fiber-reinforced polymer (FRP) sheets. This model was validated against experimental data from the literature and it showed acceptable prediction accuracy. Although carbon-FRP (CFRP) is the most commonly used composite in repairing and strengthening reinforced concrete structures, it is important to consider other types of FRP composites such as the eco-friendly basalt-FRP (BFRP) and the newly developed polyethylene terephthalate-FRP (PET-FRP). Therefore, the validated FE model was utilized to perform a parametric study for slabs having different values of concrete compressive strength (ranging from 20 to 80 MPa) and strengthened with other types of FRP. The results show that CFRP provides the highest strength enhancement with a 34.5% increase in the ultimate load, while PET-FRP provides the lowest improvement with an increase of 11.2%, compared with unstrengthened slab. The results also show that the concrete compressive strength (fc’) has moderate influence on the ultimate load. For example, increasing fc’ from 20 MPa to 80 MPa increased the predicted ultimate load for CFRP-strengthened slab from 15% to 62%. The FE model provides a suitable prediction for the ultimate strength and deformability of the strengthened two-way slabs that helps in better understanding of the performance of strengthened slabs and allows engineers to optimize design parameters.

De-coring is an essential process in the casting process chain, determining the quality and cost of production. In this study, a coupled multibody system (MBS) and finite element modeling (FEM) technique is presented to study the mechanical loads during the de-coring process. The removal of cast-in sand cores from the inner regions of the cast part by de-coring or knocking out is a complex process with dynamic loads. Currently, the process relies upon empirical knowledge and tests. Inorganic sand cores pose additional challenges in the success of the de-coring process. Increasing complexity in geometry and stringent environmental regulations compel a predictive process in the earlier stages of design. Predicting the process’ success is challenged by the dynamic non-linearities of the system. The dynamic characteristics and the interaction between hammer and casting were studied here for the first time using an industrial-based test rig, and a novel modeling approach was formulated. The results of the developed model are in good compliance with the experiments. The methodology presented in this study can be used to include a varying number of hammers and loads. The proposed approach presents the possibility to discretize the process and qualitatively assess the process parameters for optimization.

This paper thoroughly examines the application of the Finite Element Method (FEM) to the numerical modal analysis of Herøysund Bridge, focusing on the theoretical backdrop, the construction process, and FEM techniques. This work examines the specific applied FEM approaches and their advantages and disadvantages. This Herøysund Bridge analysis employs a two-pronged strategy consisting of a 3D–solid model and a shell model. To forecast the physical behavior of a structure, assumptions, modeling methodologies, and the incorporation of specific components such as pillars are applied to both approaches. This research also emphasizes the importance of boundary conditions, examining the structural effects of standard Earth gravity, a post-tensioned load, and a railing and asphalt load. The Results section thoroughly explores the mode shapes and frequencies of the 3D–solid and shell models. The conclusion of this work includes findings obtained from the study, implications for Herøysund Bridge, and a comparison of both modeling strategies. It also incorporates ideas for future research and guides employing FEM 3D–solid and shell methods to design and construct more efficient, resilient, and durable bridge structures.

The traditional finite element method (FEM) has limitations in accurately modeling crack propagation. Peridynamics, a nonlocal extension of the classical continuum theory, provides an alternative approach to remedy the limitations of the FEM but with a higher computational cost. In this paper, a peridynamic bond-based fatigue damage model is developed and incorporated into a commercial finite-element software (ABAQUS 2017) via user subroutines. Model-predicted results including the crack path spatial position and the damage accumulation rate were validated against empirical data. The predicted crack growth as a function of loading cycle and crack trajectory showed good agreement with the experimental data over 200,000 loading cycles. Therefore, the integration of the peridynamic bond-based fatigue damage model into existing FEM software provides an economical means to simulate complex fracture behaviors, such as crack growth, in a compact tension specimen examined in this paper.

Precast rectangular reinforced concrete (PRRC) beams are joined on construction sites using concrete in situ to achieve the desired length. Limited research exists on the effect of intermediate connection shapes and the types of infilled concrete on the flexural performance of PRRC beams. This paper presents a comprehensive experimental and numerical investigation into the performance of PRRC beams with various intermediate connection geometries and infilled materials under flexural loading. The study examines rectangular, triangular, and semi-circular intermediate connections, along with the performance of beams infilled with normal concrete (NC), engineered cementitious composites (ECC), ultra-high-performance ECC (UHPECC), and rubberized ECC (RECC). The experimental results indicate that the rectangular intermediate connection exhibits superior performance in terms of strength and energy absorption compared to the triangular and semi-circular shapes. Beams incorporating UHPECC demonstrated the most significant improvements in strength and energy absorption, outperforming those with ECC and RECC for any shape of intermediate connection. Moreover, beams with rectangular connections and UHPECC infill exhibited the most significant increase in energy absorption and ultimate load compared to the beams with ECC and RECC. The ultimate load of the beams with UHPECC and tensile reinforcement bar diameters of 10 mm and 12 mm increased by 13% and 29%, respectively, compared to the control beam. The energy absorption of the beams with tensile reinforcement bar diameters of 10 and 12 mm was found to be 75% and 184% higher, respectively, than the control beam. In addition, an increase in tensile bar diameter was found to enhance both the energy absorption and the ultimate load capacity of the beams, regardless of the type of infill concrete. Beams incorporating UHPECC demonstrated the most significant improvements in strength and energy absorption, outperforming those with ECC and RECC. In particular, beams with rectangular connections and UHPECC infill exhibited an increase in energy absorption and ultimate load of up to 184% and 29%, respectively. UHPC was calculated to be as high as 184%, and 29%, respectively, compared to the control beams. In addition, an increase in tensile bar diameter was found to enhance both energy absorption and ultimate load capacity. Finite element modeling (FEM) was developed and validated against the experimental results to ensure accuracy. A parametric study was conducted to study the effects of various concrete types in triangular and semi-circular connections, as well as the influence of intermediate connection length on semi-circular connections under flexural loads. The findings reveal that increasing the length of intermediate connections increases the ultimate load of the beams.

External loads applied to a box-section steel column before it is filled with concrete to increase its efficiency due to modifications in structural systems or design errors may reduce its ultimate capacity and change its structural behavior. To examine this effect, finite element modeling (FEM) has been used to simulate these columns under preloading at different ratios with many variables in the geometric dimensions of the columns. The FEM results have been investigated using 38 experimental specimens obtained from previous studies without preloading. The results demonstrated high accuracy in modeling these columns in structural behavior and ultimate load capacity. After verifying the results, 84 Concrete-Filled Steel Columns (CFSC) were modeled under different preload ratios. The results indicated that some variables have directly affected the value of the decrease in column capacity in terms of its height, wall thickness, yield stress, and preload ratios, while others were inversely proportional in terms of the cross-section dimensions and concrete strength. The preload effect ratio had two separate limits, where when it reached 70%, the maximum value of the decrease in column capacity was 10.90%. The value increased sharply reaching 19.90% when there was a preload equal to 80%. New equations have been proposed to predict the ultimate capacity of CFSC under preloading with suitable accuracy with a correlation coefficient of no less than 0.949.

The fallopian tubes are essential for human fertility, facilitating the movement of sperm and oocytes to the fertilization site and transporting fertilized oocytes to the uterus. Infertility can result from changes in the fallopian tubes due to tubal endometriosis and women’s aging. In this study, we modeled human fallopian tubes with and without endometriosis for different women’s age groups to evaluate the chances of normal sperm cells reaching the fertilization site and oocytes arriving at the uterine cavity. For this purpose, we employed a distinctive combination of simulation tools to develop a dynamic three-dimensional (3D) model of normal human sperm cells and oocytes swimming inside normal and endometriosis-affected human fallopian tubes for different women’s group ages. We observed that in tubal endometriosis cases, fewer sperm cells reach the fertilization site and more oocytes become trapped in the tube walls compared to normal tubes. Additionally, aging decreases the number of sperm cells and oocytes reaching the fertilization site in normal and endometriosis-affected tubes. Our model evaluates the mechanisms of sperm and oocyte behaviors due to women’s aging and fallopian tube issues caused by endometriosis, presenting new avenues for developing diagnostic and treatment tools for tubal endometriosis and age-related infertility issues.

To investigate the axial compression behavior of composite columns with high-strength concrete-filled steel tube flanges and honeycombed steel web (STHHC) under load during freeze–thaw cycles, 48 full-scale composite column specimens were designed with different parameters: the restraint effect coefficient (ξ), concrete strength (fcu), number of freeze–thaw cycles (nd), slenderness ratio (λ), space–height ratio (s/hw), and hole–height ratio (d/hw). The finite element models of STHHC composite columns were simulated using ABAQUS finite element software (Version: 2021). The modeling method’s rationality was verified by comparing simulation results with experimental outcomes. Based on the finite element model, a parametric analysis of the composite columns under freeze–thaw cycles was conducted, analyzing their failure modes and load-bearing processes. The results indicate that the bearing capacity of the STHHC increased with increases in ξ and fcu, and decreased with a rise in λ. In contrast, the influence of s/hw and d/hw on the ultimate bearing capacity of the composite columns was relatively minor. An equation for calculating the axial bearing capacity of the STHHC composite columns under freeze–thaw cycles was derived using statistical regression methods and considering the impact of different parameters on the axial compressive performance of the composite columns, laying the foundation for the promotion and application of this type of composite column in practical engineering projects.

In this paper, the problems of modeling the human bladder and its stress–strain state under an external static influence are considered. A method for the identification of the anisotropic biomechanical characteristics of the bladder tissue is proposed. An FEM model was created, which takes into account the fact that the bladder is surrounded by fiber, affected by surrounding organs, and partially protected by pelvic bones. The model considers the presence of constant hydrostatic pressure on the walls of the bladder when it is full. It has been shown that the isotropic mechanical characteristics of biological tissue can be used for studying the deformed state of a filled bladder if a filled bladder of 300 mL is considered as the initial non-deformed stage. This was shown by the modeling and verification of the effect of the external static force on the bladder. Numerical experiments were conducted based on the constructed model. To validate the results obtained, a series of natural experiments on the effect of external pressure on the bladder under ultrasound control were conducted. In the future, there are plans to use the constructed model to study rupture deformations of the bladder under the influence of static and dynamic loads.

The zoning excavation method is fully employed to control the deformation of foundation pits constructed in urban soft soil areas. However, the similarities and differences in forces and deformations between foundation pits excavated by the zonal method and those excavated by the conventional method still need to be further explored. In this study, the deformation was monitored and analyzed by taking the zonal excavation of a foundation pit of the ‘New World’ project in Hangzhou City as the research object. The measured results showed that the pre-built diaphragm wall for the first excavated foundation pit restricted the deformation of the first excavated diaphragm wall. The presence of extensive construction and unloading activities also changed the deformation pattern of the soil. Further, finite element simulations were carried out. The simulation results revealed that excavating the foundation pit first caused displacements in the pre-built diaphragm wall. The displacements transmitted by non-adjacent pits through the pre-built diaphragm wall were small and were concentrated at the junction of the two sub-pits. Adjacent foundation pits caused large displacements of the pre-built diaphragm wall with similar displacement patterns. The results of the study can provide effective guidance for foundation pit excavation in soft soil areas in the future.

Shear-keyed inter-modular connections (IMCs) are integral components of high-rise modular steel structures (MSSs), providing robust interconnectivity to support grouped tubular columns across modules, thereby introducing column discontinuities and distinctive structural behavior. This study conducted a comprehensive numerical assessment and theoretical analysis of the axial compression behavior of grouped tubular columns based on a validated finite element model (FEM), which captured the member-to-structural level behavior of steel hollow section (SHS) columns and accommodated geometric imperfections. An FEM was initially developed and validated using 28 axial compression tests documented in the literature, comprising 15 tests on cold-formed and 13 on hot-rolled steel hollow section (SHS) columns. The primary parameters explored in tests included material properties (stainless/carbon), processing methods (cold-formed/hot-rolled), cross-section sizes (D/B), cross-sectional or member slenderness ratios (D/tc, B/tc, or Lc/r), and the number of columns (1, 7, and 11). A comprehensive parametric numerical study involving 103 grouped tubular column FEMs then investigated the influence of initial imperfection, shear-key height (Lt), thickness (tt), steel tube length (D), width (B), thickness (tc), and height (Lc) alongside the effects of space between tube and key, and the gap between tubes. The results indicated that the load-shortening behavior of the grouped columns consists of linear elastic, inelastic, and recession stages. The failure modes observed primarily displayed an S-shaped pair of inward and outward local buckling on the outer sides and double S-shaped local buckling on the interior sides. The buckling arose near the shear key or at 1/4 or 1/2 of the column height. None of the considered models experienced global buckling. Increasing tt, Lt, tc, D, or B enhances strength and stiffness, while Lc or Lc/r linearly affects stiffness and ductility. The columns’ nominal axial strength was reduced because of the shear keys, which decreased compression yielding and caused localized elastic buckling. Subsequently, the theoretical analysis revealed that the design codes do not capture this behavior, and thus, their capacity estimate yields inaccurate findings. This discrepancy renders existing code prediction equations, including those from Indian (IS800), New Zealand (NZS400), European (EC3:1-1), Canadian (CSA S16), American (AISC360-16), and Chinese (GB50017) standards, as well as the model proposed by Li et al., non-conservative. To assure conservative results, the paper recommended modification of existing standards and proposed prediction equations based on a fourth-order differential equation that describes the actual behavior of modular steel columns grouped with shear keys. The proposed design approach accurately predicted the axial compression capacity of modular steel-grouped columns, proving conservative yet effective. This provides valuable data that could transform design and construction techniques for MSSs, extending to various column and IMC forms through adaptable design parameters. This enhancement in structural performance and safety significantly contributes to the advancement of modular construction practices.

In this paper, the effectiveness of reinforcements for flexible pavements is evaluated through an analysis of reflective cracking. Different stiffness and thickness reinforcements are considered for the rehabilitation of an already cracked pavement. The effect of the reinforcement is assessed from two different perspectives: (i) the ability to reduce stresses in the rehabilitated pavement layers, and (ii) the capacity to mitigate the crack propagation from deeper layers. A finite element model (FEM) is adopted to study the stress and strain state of the pavement layers. The pavement model has been properly validated, transitioning from a simply supported beam scheme to an elastic multilayer model. In addition, to represent crack propagation, fracture evolution is analyzed using Linear Elastic Fracture Mechanics (LEFMs) and Paris’ law. The effect of different reinforcements on the pavement is then simulated. The results show that the reinforcement performance is strictly dependent on the interlayer thickness and stiffness. In particular, high stiffness reinforcements (geomembranes) show increasing effectiveness with stiffness, both in terms of reflective cracking and stress reduction. Conversely, low stiffness reinforcements (SAMIs) show a variable trend with the stiffness modulus. In fact, extremely low stiffness is effective in slowing down crack propagation but is detrimental to the wearing course’s stress condition. However, as the stiffness increases, the likelihood of cracking in the wearing course decreases, though only a small beneficial effect is registered for crack propagation in the base layer.

The roll bonding of an experimental Al-2%Cu-2%Mn alloy with technically pure 1050A aluminum at true deformations of 0.26, 0.33 and 0.40 has been simulated using the QForm 10.3.0 FEM software. The flow stress of the Al-2%Cu-2%Mn alloy has been measured in temperature and strain rate ranges of 350–450 °C and 0.1–20 s−1, respectively. The simulation results suggest that the equivalent strain in the cladding layer is more intense than that in the base layer, reaching 1.0, 1.4 and 2.0 at strains of 0.26, 0.33 and 0.40, respectively. The latter fact favors a decrease in the difference between the flow stresses of the rolled sheet layer contact surfaces by an average of 25% at the highest strain. The experimental roll bonding has achieved good layer adhesion for all the test samples. The average peeling strength of the samples produced at strains of 0.26 and 0.33 proves to be 12.6 and 18.4 N/mm, respectively, and at a strain of 0.40, it has exceeded the flow stress of the 1050A alloy cladding layer. The change in the rolling force for different rolling routes has demonstrated the best fit with the experimental data.

Purpose: With age, there is an anterior shift of the ciliary body in the eye, which alters the angle of zonular insertion in older eyes compared with younger eyes. This study aims to simulate lens accommodation with different zonular angles to consider the influence of zonular position on lens accommodative capacity. Methods: Models were constructed based on lenses aged 11, 29, and 45 years using a 2D axisymmetric structure that included a capsule, cortex, nucleus, and zonular fibers. The different zonular fibers were simulated by changing the position of the point where the zonular fibers connect to the ciliary body. The effect of the different zonular fiber insertion angles on the model shape and optical power was analyzed. Results: The models show that smaller angles made by zonular fibers to the surface of the lens lead to larger optical power changes with simulated stretching. When the models were stretched, and when varying the zonule angles, the optical power of the 11-, 29-, and 45-year-old models changed up to 0.17 D, 0.24 D, and 0.30 D, respectively. The effect of zonular angles on the anterior radius of curvature of the anterior surface varied by 0.29 mm, 0.23 mm, and 0.25 mm for the 11-, 29-, and 45-year-old models, respectively. Conclusions: Larger zonular fiber insertion angles cause smaller deformation and less accommodative change, while parallel zonules induce the largest change in lens shape.

The circular hollow steel-reinforced concrete (HSRC) column consists of an inner circular hollow steel tube and outer circular hollow reinforced concrete (RC). This design provides several advantages, including being lightweight, having a wide sectional profile, and having a high flexural stiffness. This paper aims to investigate the behavior of the circular HSRC columns under axial compression through testing and finite element (FE) modeling. An FE model was established to simulate the circular HSRC columns under axial compression, which was validated against the test data. Additionally, the load distribution and the interface stress between the outer hollow RC and inner steel tube were analyzed. Subsequently, a systematic parametric analysis was conducted on the diameter (d) and thickness (t) of the steel tube; slenderness ratio (λ); strength of concrete (fcu); yield strength of steel tube (fsy), longitudinal rebar (fly), and stirrup (fgy); as well as the stirrup spacing (s). The critical influencing factors of the circular HSRC columns under axial compression were identified. fcu, λ, d, fly, and fsy dramatically influence the bearing capacity, and the stiffness is notably affected by λ and fcu. Finally, three simplified design methods were summarized and evaluated for calculating the bearing capacity of the circular HSRC columns under axial compression.

The human heart’s remarkable vitality necessitates a deep understanding of its mechanics, particularly concerning cardiac device leads. This paper presents advancements in finite element modeling for cardiac leads and 3D heart models, leveraging computational simulations to assess lead behavior over time. Through detailed modeling and meshing techniques, we accurately captured the complex interactions between leads and heart tissue. Material properties were assigned based on ASTM (American Society for Testing and Materials) standards and in vivo exposure data, ensuring realistic simulations. Our results demonstrate close agreement between experimental and simulated data for silicone insulation in pacemaker leads, with a mean force tolerance of 19.6 N ± 3.6 N, an ultimate tensile strength (UTS) of 6.3 MPa ± 1.15 MPa, and a percentage elongation of 125% ± 18.8%, highlighting the effectiveness of simulation in predicting lead performance. Similarly, for polyurethane insulation in ICD leads, we found a mean force of 65.87 N ± 7.1 N, a UTS of 10.7 MPa ± 1.15 MPa, and a percentage elongation of 259.3% ± 21.4%. Additionally, for polyurethane insulation in CRT leads, we observed a mean force of 53.3 N ± 2.06 N, a UTS of 22.11 MPa ± 0.85 MPa, and a percentage elongation of 251.6% ± 13.2%. Correlation analysis revealed strong relationships between mechanical properties, further validating the simulation models. Classification models constructed using both experimental and simulated data exhibited high discriminative ability, underscoring the reliability of simulation in analyzing lead behavior. These findings contribute to the ongoing efforts to improve cardiac device lead design and optimize patient outcomes.

Serious cracks were found in the pylon of a cable-stayed bridge without backstays. Based on forensic damage investigation, this paper uses the finite element (FE) method incorporating Building Information Modeling (BIM) to analyze the causes of cracking. The BIM model is established based on the survey of design, construction, and service information of the bridge. Then, FE analysis is conducted using BIM information. Finally, the causes of cracking in different regions of the pylon are explained in detail. The results show that the FE simulation agrees well with the inspected distribution of cracks, and the causes of cracks are closely related to the pylon construction process. The main cause of the cracks is the shrinkage difference between concrete segments of different ages. The anchorage effect of stayed cables also causes inclined cracks perpendicular to the cable direction. The combination of temperature load and concrete shrinkage results in cracks at the root of the pylon, and the reduction in cable forces exacerbates the cracking.

Collagen-based scaffolds have been widely used in tissue engineering. The alignment of collagen fibers and the degree of crosslinking in engineering tissue scaffolds significantly affect cell activity and scaffold stability. Changes in microarchitecture and crosslinking degree also impact the mechanical properties of collagen scaffolds. A clear understanding of the effects of collagen alignment and crosslinking degrees can help properly control these critical parameters for fabricating collagen scaffolds with desired mechanical properties. In this study, combined uniaxial mechanical testing and finite element method (FEM) were used to quantify the effects of fiber alignment and crosslinking degree on the mechanical properties of collagen threads. We have fabricated electrochemically aligned collagen (ELAC) and compared it with randomly distributed collagen at varying crosslinking degrees, which depend on genipin concentrations of 0.1% or 2% for crosslinking durations of 1, 4, and 24 h. Our results indicate that aligned collagen fibers and higher crosslinking degree contribute to a larger Young’s modulus. Specifically, aligned fiber structure, compared to random collagen, significantly increases Young’s modulus by 112.7% at a 25% crosslinking degree (0.1% (4 h), i.e., 0.1% genipin concentration with a crosslinking duration of 4 h). Moreover, the ELAC Young’s modulus increased by 90.3% as the crosslinking degree doubled by changing the genipin concentration from 0.1% to 2% with the same 4 h crosslinking duration. Furthermore, verified computational models can predict mechanical properties based on specific crosslinking degrees and fiber alignments, which facilitate the controlled fabrication of collagen threads. This combined experimental and computational approach provides a systematic understanding of the interplay among fiber alignment, crosslinking parameters, and mechanical performance of collagen scaffolds. This work will enable the precise fabrication of collagen threads for desired tissue engineering performance, potentially advancing tissue engineering applications.

Postmortem human eyes were subjected to optic nerve (ON) traction in adduction and elevated intraocular pressure (IOP) to investigate scleral surface deformations. We incrementally adducted 11 eyes (age 74.1 ± 9.3 years, standard deviation) from 26° to 32° under normal IOP, during imaging of the posterior globe, for analysis by three-dimensional digital image correlation (3D-DIC). In the same eyes, we performed uniaxial tensile testing in multiple regions of the sclera, ON, and ON sheath. Based on individual measurements, we analyzed eye-specific finite element models (FEMs) simulating adduction and IOP loading. Analysis of 3D-DIC showed that the nasal sclera up to 1 mm from the sheath border was significantly compressed during adduction. IOP elevation from 15 to 30 mmHg induced strains less than did adduction. Tensile testing demonstrated ON sheath stiffening above 3.4% strain, which was incorporated in FEMs of adduction tethering that was quantitatively consistent with changes in scleral deformation from 3D-DIC. Simulated IOP elevation to 30 mmHg did not induce scleral surface strains outside the ON sheath. ON tethering in incremental adduction from 26° to 32° compressed the nasal and stretched the temporal sclera adjacent to the ON sheath, more so than IOP elevation. The effect of ON tethering is influenced by strain stiffening of the ON sheath.

This paper presents an extended work on the Finite Element Method (FEM) simulation of Love Wave (LW) sensors in a liquid medium. Two models are proposed to simulate the multiphysical response of the sensor. Both are extensively described in terms of principle, composition and behavior, making their applications easily reproducible by the sensor community. The first model is a Representative Volume Element (RVE) simulating the transducer and the second focuses on the sensor’s longitudinal (OXZ) cut which simulates the multiphysical responses of the device. Sensitivity of the LW device to variations in the rheological and dielectric properties of liquids is estimated and then compared to a large set of measurements issued from LW sensors presenting different technological characteristics. This integral approach allows for a deeper insight into the multiphysical behavior of the LW sensor. This article also explores the advantages and drawbacks of each model. Both are in good accordance with the measurements and could be used for various applications, for which a non-exhaustive list is proposed in the conclusion.

This paper proposes the structural design and calculation model of stepped three-row pile and verifies its antioverturning and antisliding stability, based on the Xinghe Yabao deep foundation pit project in Shenzhen, China. The three-row pile model is constructed using finite element software, and the force and deformation of the piles are analyzed. The influence of the direction of the prestressing anchors on the support effect of the three-row pile is investigated by simulating the prestressing anchors in three directions: oblique, horizontal, and vertical. The results show that the combined support effect of the oblique anchor and the three-row pile is the most effective, resulting in the smallest deformation, followed by the horizontal anchor, and the vertical anchor produces the largest deformation. Finally, the innovative construction method of the three-row pile removal and the basement top-down construction method is proposed. The three-dimensional model of the tower building and the basement is established by the finite element software to simulate the structural grading load and the cooperative construction of the supporting structure and the basement structure. The research results have greater engineering application value and significant economic benefits, which could provide reference and guidance for the design and construction of deep foundation pits in similar projects.

The influence of hot-top designs with different heat capacities on the distribution of positive and negative macrosegregation was investigated on a 12 metric tonne (MT) cast ingot made using Cr-Mo low-alloy steel. The three-dimensional finite element modeling code THERCAST® was used to simulate the thermo-mechanical phenomena associated with the solidification process, running from filling the mold until complete solidification. The model was validated on an industrial-scale ingot and then utilized to evaluate the influence of the thermal history of the hot-top, a crucial component in the cast ingot setup. This assessment aimed to comprehend changes in solidification time, temperature, and heat flux—all of which contribute to the determination of macrosegregation severity. The results showed that preheating the hot-top had a minor effect on solidification time, while modifications of thermal conductivity in the hot-top region increased the solidification time by 31%, thereby significantly affecting the macrosegregation patterns. The results are discussed and interpreted in terms of the fundamental mechanisms governing the kinetics of solidification and macrosegregation phenomena.

Unreinforced masonry has been for centuries one of the most widespread constructive techniques for both massive structures and civil buildings (e.g., palaces, hospitals, houses), for the most still standing nowadays. Their future conservation relies on (i) their protection from main natural threats (e.g., earthquakes) and (ii) updating to current functionality and hygrothermal standards. In the former framework, existing masonry buildings proved to have some intrinsic vulnerabilities, depending on composition (units and binder) and structural typologies. Based on experience gathered from seismic events, various retrofitting techniques have been proposed. In such a context, the use of cross-laminated timber (CLT) components is a very promising solution, in terms of compatibility with built heritage and integration of seismic and hygrothermal performances. This paper aims at improving the knowledge of the structural performances of compound timber–masonry interventions by numerical simulations carried out at (i) pier scale and (ii) building full scale via finite element modeling and nonlinear static analyses (pushover). First, a coupled timber–masonry wall was simulated and underwent sensitivity analyses with the properties of both components varying; then, the optimized solution was applied to a case study to assess the intervention benefits, and the results were also cross-checked with those of more traditional interventions (e.g., grout injections).

In tissue formation and regeneration processes, cells often move collectively, maintaining connections through intercellular adhesions. However, the specific roles of cell–substrate and cell-to-cell mechanical interactions in the regulation of collective cell migration are not yet fully understood. Finite element modeling (FEM) may be a way to assess more deeply the biological, mechanical, and chemical phenomena behind cell adhesion. FEM is a powerful tool widely used to simulate phenomena described by systems of partial differential equations. For example, FEM provides information on the stress/strain state of a cell adhering to a substrate, as well as on its mechanobiological behavior. This review paper, after briefly describing basic principles of cell adhesion, surveys the most important studies that have utilized FEM to investigate the structural response of a cell adhering to a substrate and how the forces acting on the cell–substrate adhesive structures affect the global cell mechanical behavior.

Lightweight structural materials are required to increase the mobility of fission batteries. The materials must feature a robust combination of mechanical properties to demonstrate structural resilience. The primary objective of this project is to produce lightweight structural materials whose strength-to-weight ratios exceed those of the current widely used structural materials such as 316L stainless steels (316L SS). To achieve this, advanced modeling and simulation tools were employed to design lattice structures with different lattice parameters and different lattice types. A process was successfully developed for transforming lattice-structures models into Multiphysics Object Oriented Simulation Environment (MOOSE) inputs. Finite element modeling (FEM) was used to simulate the uniaxial tensile testing of the lattice-structured parts to investigate the stress distribution at a given displacement. The preliminary results showed that the lattice-structured sample displayed a lower Young’s modulus in comparison with the solid material and that the unit cell size of the lattice had a minimal effect. The novelty here is to apply up-front modeling to determine the best structure for the application before actually producing the sample. The approach of using modeling as a guiding tool for preliminary material design can significantly save time and cost for material development.

Three-dimensional concrete printing (3DCP) is of great interest to scientists and the construction industry to bring automation to structural engineering applications. However, studies on the thermal performance of three-dimensional printed concrete (3DPC) building envelopes are limited, despite their potential to provide a long-term solution to modern construction challenges. This work is a numerical study to examine the impact of infill geometry on 3DPC lattice envelope thermal performance. Three different lattice structures were modeled to have the same thickness and nearly equal contour lengths, voids, and insulation percentages. Additionally, the effects of filament width and the application of granular insulating materials (expanded polystyrene beads and loose-fill perlite) were also studied. Finally, the efficacy of insulation was established. Results show that void area affects the thermal performance of 3DPC envelopes under stagnant air conditions, while web length, filament width, and contact (intersection) area between the webs and face shells affect the thermal behavior when cavities are filled with insulating materials due to thermal bridging. The thermal efficiency of insulation, which shows the effective use of insulation, varies between 26 and 44%, due to thermal bridges.

Many rooms struggle with the absorption of low-frequency sound due to its long wavelengths. The integration of existing solutions into these spaces is often challenging due to their intricate installations and large depths. To address this problem, a new type of resonance absorber has been developed: the Distributed Mode Absorber (DMA). It consists of a thin vibrating front panel and a volume of enclosed air behind it. This straightforward structure can be utilized to create acoustically functional furniture that can be seamlessly incorporated into rooms. This article is devoted to the structural optimization of the DMA front panel, using the Acoustic Black Hole (ABH) effect known within structural dynamics. A numerical model is constructed using a Finite Element Analysis (FEA) and examined numerically. Several geometric parameters of the ABH are studied with regard to their influence on the vibrations of the front panel. Prototypes are developed and manufactured based on these insights. The quality of the numerical model is verified during the subsequent validation. Finally, the sound absorption of the improved DMA is compared with that of the reference DMA.

The incorporation of carbon nanotubes (CNTs) can enhance the mechanical properties of concrete. The stress–strain curves of CNT-reinforced concrete under uniaxial compression are investigated through an experimental program with different CNT and steel fiber proportions considered. The test results demonstrate that CNTs can increase both peak stress and peak strain, and steel fibers can further enhance the effect of CNTs. Additionally, steel fibers can effectively enhance both the strength and ductility. Theoretical models for the peak strain, initial elastic modulus, toughness index and relative absorbed energy are established. A theoretical model for the uniaxial compressive constitutive relationship of CNT-reinforced concrete considering CNT and steel fiber content is developed. Finite element (FE) modelling is developed to simulate the axial compression behavior of CNT-reinforced concrete.

Asphalt mixtures exhibit complex mechanical behaviors due to their multiphase internal structures. To provide better characterizations of asphalt pavements under various forms of potential distress, a two-dimensional (2D) finite element simulation based on images of asphalt mixtures can be used to increase computational efficiency and reduce labor consumption. Nonetheless, using a representative image to eliminate the influence of dimension reduction from three dimensions to two dimensions is of great significance for attaining a reliable simulation result. Therefore, in this study, we investigated the consequence of dimension reduction for open-graded asphalt mixtures (denoted as OGFC-16), including a comprehensive characterization of these 2D models in terms of their morphologies and the similarities between them. This study aimed to reveal the variation in a 2D finite element simulation when applied to open-graded asphalt mixtures. Structural compositions, gradations, the aspect ratios of aggregates, and aggregate orientations were counted and calculated. In addition, the cosine similarity and structural similarity index measure (SSIM) were also calculated. Consequently, we performed a statistical analysis on the aforementioned indicators to quantitatively identify the discrepancy in the 2D images caused by dimension reduction. The results demonstrate that this 2D simulation might not be sufficient for representing the realistic mechanical performance of asphalt mixtures due to the remarkable variations in the image morphologies in different 2D images. However, the basic rules of stress behavior within structures can be accurately simulated. A compensative methodology for conducting a 2D simulation of open-graded asphalt mixtures should be based on a morphological characterization, considering structural compositions and the structural similarity index measure.

The fast, convenient, and accurate determination of railroad cars’ load mass is critical to ensure safety and allow asset counting in railway infrastructure. In this paper, we propose a method for modeling the mechanical deformations that occur in the rail web under the influence of a static load transmitted through a railway wheel. According to the proposed method, a railroad car’s weight can be determined from the rail deformation values. A solid model of a track section, including a railroad tie, rail, and wheel, is developed, and a multi-physics simulation technique that allows for the determination of the values of deformations and mechanical stresses in the strain gauge installation areas is presented. The influence of the loaded mass, the temperature of the rail, and the wheel position relative to the strain gauge location is considered. We also consider the possibility of using artificial neural networks to determine railroad cars’ weight without specifying the coordinates of the wheel position. The effect of noise in the data on the accuracy of determining the railroad car weight is considered.

Nomex honeycomb composite (NHC) cores have seen significant growth in recent years, particularly in the aeronautics, aerospace, naval and automotive industries. This development presents significant challenges in terms of improving machining quality, requiring the use of specialized cutting tools and favorable cutting techniques. In this context, experimental studies have been carried out to highlight the characteristics of the milling of NHCs by rotary ultrasonic machining (RUM). However, the rapid motion of the cutting tool and the inaccessibility of the tool/part interface prevent the visualization of the chip formation process. For this purpose, a three-dimensional numerical model for milling the NHC structure using RUM technology was developed by Abaqus Explicit software. On the basis of this model, the components of the cutting force, the quality of the machined surface and the chip accumulation in front of the cutting tool were analyzed. The numerical results agree with the experimental tests, demonstrating that the use of RUM technology effectively reduces the cutting force components. An in-depth analysis of the influence of feed component Fy on the quality of the generated surface was carried out, revealing that the surface quality improved with low values of feed component Fy. Furthermore, the impact of ultrasonic vibrations on the accumulation of chips in front of the cutting tool is particularly optimized, in particular for large amplitudes.

Phase-change materials (PCMs) are commonly employed in building service equipment to regulate indoor temperatures and reduce energy consumption. This study conducted multi-scale finite element modeling to analyze the steady-state and dynamic thermal behavior of a hydronic radiant floor heating system integrated with macro-encapsulated PCMs. It predicted performance values for hydronic floor heating with and without macro-encapsulated PCMs. The study assessed the impact of the PCM volume fraction, heating water temperature, capsule thermal conductivity, and shape on the thermal performance of hydronic floor heating through various finite element models. The predictive capability of the finite element model was validated using experimental data, showing good agreement. Although the inclusion of PCMs lowered the floor temperature, it improved temperature distribution and retained heat when the system was inactive. The PCM volume fraction significantly influenced the performance of the hydronic floor. However, the shape of the macro-encapsulated PCM and thermal conductivity of the shell had minimal effects in the studied case. For instance, increasing the thermal conductivity of the shell of the PCM capsule fifty times from 0.3 to 15 W m−1 K−1 resulted in an increase in surface temperature by 1.2 °C.

Two-photon lithography (TPL) is a laser-based additive manufacturing technique that enables the printing of arbitrarily complex cm-scale polymeric 3D structures with sub-micron features. Although various approaches have been investigated to enable the printing of fine features in TPL, it is still challenging to achieve rapid sub-100 nm 3D printing. A key limitation is that the physical phenomena that govern the theoretical and practical limits of the minimum feature size are not well known. Here, we investigate these limits in the projection TPL (P-PTL) process, which is a high-throughput variant of TPL, wherein entire 2D layers are printed at once. We quantify the effects of the projected feature size, optical power, exposure time, and photoinitiator concentration on the printed feature size through finite element modeling of photopolymerization. Simulations are performed rapidly over a vast parameter set exceeding 10,000 combinations through a dynamic programming scheme, which is implemented on high-performance computing resources. We demonstrate that there is no physics-based limit to the minimum feature sizes achievable with a precise and well-calibrated P-TPL system, despite the discrete nature of illumination. However, the practically achievable minimum feature size is limited by the increased sensitivity of the degree of polymer conversion to the processing parameters in the sub-100 nm regime. The insights generated here can serve as a roadmap towards fast, precise, and predictable sub-100 nm 3D printing.