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Thin-walled tubular deployable composite boom (DCB) has gained significant attention due to its lightweight, simple structure and high packaging efficiency. The experimental and numerical simulation methods were employed in this paper to investigate the folding behavior of the DCB. Using T700/epoxy unidirectional reinforced prepreg as raw material, DCB specimens were prepared by the vacuum bag method. To complete the folding experiments of DCB specimens, a folding mechanism was designed and manufactured. Folding experiments of DCB specimens were conducted and folding moment versus rotational displacement curves were measured. In addition, a Finite Element Model (FEM) was established to predict the folding behavior of the DCB. Different failure criteria were considered in the numerical analysis, including the Tsai‐Hill criterion and maximum stress criterion. Prediction results using the FEM were compared with experimental results, and both sets of results were in good agreement. It is shown that the DCB can achieve the folding function without failure. The research results in this paper are of great significance to the practical engineering application of the DCB. [Display omitted] • Six tubular deployable composite boom specimens and a precise folding mechanism were designed and prepared. • Folding experiments were conducted to measure the folding moment and rotational displacement curves. • A finite element model for predicting the folding behavior of the tubular deployable composite boom was established. [ABSTRACT FROM AUTHOR]

Alternating current (ac) losses in conductor-on-rounded-core (CORC) cables of YBCO high-temperature superconducting (HTS) tapes are a significant challenge in HTS power applications. This study employs two finite element analysis (FEA) models to investigate the contributions from different ac loss components and provide approaches for reducing ac losses in cables. An FEA model based on the T-A formulation treats the cross section of thin superconducting layers as 1D lines and, therefore, only can predict the ac loss generated by the perpendicular magnetic field. In contrast, the model based on H-formulation can be performed on the actual 2D rectangular cross section HTS tapes to provide the total ac losses generated by magnetic fluxes penetrating from both the edges and surfaces of HTS tapes, although this model requires more computing time and memory. The 1D and 2D simulation models were validated by cross comparing the results from both models and by comparing sub-section and full cross section models. Subsequently, two models relate cable design and operational parameters to the surface and edge losses of a two-layer CORC cable by considering the (1) relative contributions of edge and surface losses to the overall ac losses; (2) effect of the current distribution between inner and outer HTS layers on ac losses; (3) impact of the tape alignment on ac losses in each HTS layer; (4) influence of the thickness of HTS layers on ac losses; (5) effect of size and number of inter-tape gaps on ac losses; and (6) contribution frequency on the ac losses. The research results given in this paper are therefore not only valuable to suggest strategies for reducing ac loss in multi-layer cables but also for developing more accurate and effective methods to calculate ac loss in CORC HTS cables. [ABSTRACT FROM AUTHOR]

An epiretinal membrane (ERM) is a fibrocellular proliferation on the inner surface of the retina causing blurred and distorted central vision. Surgery is the only effective method for ERM removal. This paper investigated the mechanical properties of ERM peeling using the finite element (FE) method. A FE model of ERM formation on the retina surface was constructed. The failure criterion was applied to the attachment pegs to represent the adhesive force between the ERM and retina. The simulation results were consistent with the experimental data in published research. The maximum peeling force was 4.1 mN at a peeling velocity of 2 mm/s and an angle of 30°. The peeling force was minimum at the peeling angle of 45° and increased with the increase in peeling velocity and Young's modulus of the membrane. The outcome of this paper can improve the safety and efficiency of ERM removal. [ABSTRACT FROM AUTHOR]

The ability to determine the condition of paper (e.g. its brittleness) and its permanence is a need in libraries and archives. This study investigates various bend tests and applies these tests to aged paper with the goal of finding easy, non-destructive tests to determine the mechanical properties of paper. The cantilever test was previously shown to accurately assess mechanical properties of paper-based materials, such as elastic and bending moduli as well as the bending length. This work investigates the hanging pear loop and clamped fold tests and compares the results with those found with the cantilever test. The results show that the strain and curvature induced by the two tests are much larger than those experienced in the cantilever test. This large strain and curvature induce plastic behaviour and make the hanging pear loop and clamped fold tests inappropriate for use on paper-based materials. [ABSTRACT FROM AUTHOR]

The bone lacunar-canalicular system (LCS) is a unique complex 3D microscopic tubular network structure within the osteon that contains interstitial fluid flow to ensure the efficient transport of signaling molecules, nutrients, and wastes to guarantee the normal physiological activities of bone tissue. The mass transfer laws in the LCS under microgravity and hypergravity are still unclear. In this paper, a multi-scale 3D osteon model was established to mimic the cortical osteon, and a finite element method was used to numerically analyze the mass transfer in the LCS under hypergravity, normal gravity and microgravity and combined with high-intensity exercise conditions. It was shown that hypergravity promoted mass transfer in the LCS to the deep lacunae, and the number of particles in lacunae increased more significantly from normal gravity to hypergravity the further away from the Haversian canal. The microgravity environment inhibited particles transport in the LCS to deep lacunae. Under normal gravity and microgravity, the number of particles in lacunae increased greatly when doing high-intensity exercise compared to stationary standing. This paper presents the first simulation of mass transfer within the LCS with different gravity fields combined with high-intensity exercise using the finite element method. The research suggested that hypergravity can greatly promote mass transfer in the LCS to deep lacunae, and microgravity strongly inhibited this mass transfer; high-intensity exercise increased the mass transfer rate in the LCS. This study provided a new strategy to combat and treat microgravity-induced osteoporosis. [ABSTRACT FROM AUTHOR]

Based on the classical grid theory and related regulations, a structure model of a fiber-wound composite gas cylinder was designed in this paper. Based on the design results, a finite element model of a fully wound composite cylinder of an aluminum alloy inner liner with a working pressure of 35 MPa was established based on the ABAQUS software, and its stress distribution under working pressure and minimum burst pressure was analyzed. According to engineering experience, the pressure tolerance of composite cylinders can be improved by proper autofrettage pressure before working pressure, so the influence of autofrettage pressure was analyzed in this paper. The optimum autofrettage pressure was selected by setting the autofrettage gradient, and damage analysis was carried out on the cylinder with nominal working pressure of 35 MPa based on the Hashin failure criterion. The results show the initial damage sequence: matrix stretching occurs before the fiber stretching, and the damage generally starts from the spiral-wound layer. The tensile damage first appears in the transition section between the head and the barrel body, and the damage of the spiral-wound layer develops from the inner layer of the wound layer to the outer layer, while the damage of the circumferentially wound layer develops from the outer layer to the inner layer. [ABSTRACT FROM AUTHOR]

Nonlocal problems involving fourth-order terms pose several difficulties such as numerical discretization and its related convergences analysis. In this paper, the well-posedness of the extended Fisher-Kolmogorov equation with nonlocal diffusion is first analyzed using the Faedo-Galerkin technique and the classical compactness arguments. Moreover, we adopt a BDF2 scheme for time discretization and a mixed Galerkin scheme for spatial discretization. Then, we derive the optimal order convergence rates of the fully discrete system. Finally, some numerical simulations and convergence results are provided to confirm the theoretical results and the accuracy of the proposed scheme. [ABSTRACT FROM AUTHOR]

One-dimensional fourth-order boundary value problems (BVPs) play a critical role in engineering applications, particularly in the analysis of beams. Current numerical investigations primarily concentrate on homogeneous boundary conditions. In addition to its high precision advantages, the Hermite finite element method (HFEM) is capable of directly computing both the function value and its derivatives. In this paper, both the cubic and quintic HFEM are employed to address two prevalent non-homogeneous fourth-order BVPs. Furthermore, a priori error estimations are established for both BVPs, demonstrating the optimal error convergence order in H 2 semi-norm and L 2 norm. Finally, a numerical simulation is presented to validate the theoretical results. [ABSTRACT FROM AUTHOR]

Phase change material (PCM) mixed in soil can effectively adjust the subgrade temperature. In order to analyze the temperature field change of soil containing PCM more accurately from the microscopic point of view, it is a key problem to construct a refined geometric model. This paper scans the fracture plane of soil containing PCM through the stereoscopic microscope and prepares the label image corresponding to the sample image. Then a U-Net semantic segmentation model is established, which can accurately recognize PCM area and soil area. Finally, a geometric model of soil containing PCM that is consistent with reality is established, and its heat transfer characteristics are analyzed by finite element method. The accuracy evaluation of the segmentation model and the visualization of the recognition results show that the evaluation indexes of U-Net are the best. P, R, F1, and MIoU of U-Net are 0.889, 0.918, 0.903, and 0.901, respectively. The refined model established in this paper can not only observe the overall temperature regulation effect of the material but also accurately describe the internal temperature distribution details of soil containing PCM during heat transfer. Through numerical simulation, it is found that the maximum temperature of mixture decreases by 1.6 °C and the minimum temperature of mixture increases by 2.3 °C. [ABSTRACT FROM AUTHOR]

Most of the Italian infrastructures have been built since the mid‐twentieth century. Prestressed concrete (PC) has been widely used, especially for bridges and viaducts. These structures have proved effective over time, but their performance could be affected by degradation phenomena (i.e., corrosion of the tendons and residual prestressing) or construction defects (i.e., grouting of the ducts), which need to be accurately modeled. This paper focuses on the flexural response of two reduced‐scale, posttensioned, PC bridge girders, prestressed with two different jacking forces and tested under four‐point bending configuration. Four multidimensional numerical models were developed to simulate the experimental behaviors of the selected specimens, using two alternative computational strategies, namely, the finite element method (FEM) and applied element method (AEM). Three FEM modeling were considered, ranging from one‐dimensional lumped‐plasticity models to two‐dimensional and three‐dimensional (3D) spread‐plasticity models. Besides, 3D AEM models were developed into another software package. The accuracy and the computational costs of the two numerical strategies are discussed in this paper. Also, the main features of each numerical modeling technique are addressed, including comparisons between numerical and experimental global response data as well as the statistical characterization of the model error. Based on these different features, the authors also suggest the most suitable numerical strategy for future studies on PC girders. [ABSTRACT FROM AUTHOR]

The paper describes the authors' contribution to the evolution of numerical simulation of concrete structures based on the nonlinear finite element method. The formulation of constitutive relations for concrete material is a keystone of this approach, whereas cracking is the dominant feature. Two distinct methods of crack modeling were developed, namely, the discrete and the smeared crack models. Blind prediction benchmarks of the experimental tests are used for model verification. Application of the numerical simulation in the design of concrete structures is supported by the global safety format, where the uncertainty sources, due to the material and the resistance model, are considered. A structural assessment of a prestressed reinforced concrete viaduct is shown as an example of application. [ABSTRACT FROM AUTHOR]

This paper examines the engineering background of the main shaft of Ruihai Mining Group Company in Laizhou City, with a focus on the loose permeable stratum located in the frozen section of the shaft. Field measurements and data collection, including brine temperature and surface subsidence values, were conducted using temperature and hydrological boreholes. The distribution of the frozen wall temperature field was then numerically simulated using finite element analysis, and the results were compared and analyzed with field data. Scanning electron microscopy (SEM) was used to qualitatively describe the microstructure of the soft rock in the frozen section under different freezing schemes. Based on the formation of the frozen wall, a new construction scheme for freezing and excavating the internal and external circles of the vertical shaft in the loose permeable stratum is proposed. This involves the implementation of "inner and outer double-circles of freezing holes" and a comparison of the freezing effect of the temperature field before and after the improvement. The results indicate that the new freezing scheme can accelerate the freezing rate of the surrounding rock of the shaft, and reduce the time required for closure by more than 10 days. After applying the improved scheme for 60 days, the temperature is lowered by 4–5 ℃ compared to the original scheme, and the thickness of the frozen wall is approximately 4.8 m, significantly thicker than before. These findings demonstrate the effectiveness of adding an inner circle of freezing holes in achieving the lowest temperature which contributes to subsequent shaft excavation. The new scheme holds significant implications for the safe construction of shaft excavation in complex hydrogeological areas. Highlights: The main shaft in the unique geological conditions and the impact of tidal activities on freezing performance are analyzed. The new construction scheme incorporating "inner and outer double-circles of freezing holes" significantly improves freezing efficiency and reduces closure time. The improved scheme results in a thicker frozen wall and lower temperature compared to the original scheme. The findings have important implications for the safe construction of shaft excavation in complex coastal hydrogeological areas. [ABSTRACT FROM AUTHOR]

Hydraulic fracturing unlocks previously inaccessible hydrocarbons in unconventional reservoirs by creating artificial pathways in the unconventional reservoir. Numerical simulation expands the scope of hydraulic fracturing design for various reservoir conditions. This review paper explores the synergy between numerical simulation and hydraulic fracturing modeling, focusing on critical elements like geomechanical behavior, geological conditions, and fluid dynamics. Analytical models in hydraulic fracturing design are discussed to underscore their foundational importance. The assumption of constant fracture height limits the application of Perkins–Kern–Nordgren model (PKN) and Kristianovich‐Geertsma‐de Klerk model (KGD). Radial models assume 3D flow but lack reliability in nonradial settings, and the Pseudo 3D model (P3D) shares PKN's assumptions with variable fracture height, sacrificing some details for efficiency. Planar 3D model (PL3D) enhances accuracy by discarding PKN's elastic response assumption but requires extended computation. Unconventional fracture model is effective for complex scenarios but relies on DFN modeling parameters for accuracy. The choice of numerical simulation method in hydraulic fracturing depends on the specific aspect studied, each with its strengths and limitations. For instance, boundary element methods are efficient for exterior problems, finite element modeling suits 3D nonplanar fractures, and the extended finite element method excels in hydraulic and natural fracture interactions. Peridynamics shows potential but needs further development for cost‐effectiveness. PFC and UDEC/3DEC‐based simulations can explore microscopic mechanisms. Combining these methods with other approaches provides a comprehensive study of realistic reservoir conditions. This review guides the selection of a suitable numerical simulation methodology based on the study's scope. [ABSTRACT FROM AUTHOR]

Vibrating flip-flow screens are widely employed in the deep screening processes of coal washing, solid waste treatment, metallurgy, and other fields, playing a crucial role in enhancing product quality and production efficiency. The screen surface and material movement of vibrating flip-flow screens are highly complex, and there is currently insufficient understanding of their screening mechanism, limiting further optimization and application. In this paper, the Discrete Element Method (DEM), Finite Element Method (FEM), and Multi-Body Dynamics (MBD) were integrated to establish a numerical coupling model for vibrating flip-flow screens, considering material loads, screen surface deformation, and screen machine dynamics. The Response Surface Method was utilized to analyze the significant impact of relative amplitude, tension amount, amplitude of driving screen frame, vibration frequency, and screen surface inclination on screening efficiency and material velocity. The results indicate that the most significant factor influencing the screening of flip-flow screens is the screen surface inclination. Based on a BP neural network, a five-degree-of-freedom inclination surrogate model for flip-flow screens was established. The whale algorithm was employed for multi-objective optimization of the surrogate model, resulting in a screen surface inclination distribution that meets the requirements of different operating conditions. [ABSTRACT FROM AUTHOR]

3D Concrete Printing (3DCP) is a rapidly evolving technology that allows for the efficient and accurate construction of complex concrete objects. In this paper, a numerical modelling approach is presented for the simulation of the printing process of cementitious materials, based on the homogeneous fluid assumption. To cope with the large deformations of the domain and the nonlinearity resulting from the use of a non-Newtonian rheological law, the Navier–Stokes equations are solved in the framework of the Particle Finite Element Method (PFEM). Furthermore, tailored solutions have been formulated and implemented for the time-dependent moving boundary conditions at the nozzle outlet and for the efficient handling of the inter-layer contact in the same PFEM framework. The overall computational cost is decreased by the implementation of an adaptive de-refinement technique, which drastically reduces the number of degrees of freedom in time. The proposed modelling approach is finally validated by simulating the printing process of six rectilinear layers and one multi-layer "wall". The results show good agreement with the experimental data and provide valuable insights into the printing process, paving the way for the use of numerical modelling tools for the optimization of materials and processes in the field of 3D Concrete Printing. [ABSTRACT FROM AUTHOR]

This paper presents an efficient and reliable approach to study the low-velocity impact response of woven composite shells using 3D finite element models that account for the physical intralaminar and interlaminar progressive damage. The authors' previous work on the experimental assessment of the effect of thickness on the impact response of semicylindrical composite laminated shells served as the basis for this paper. Therefore, the finite element models were put to the test in comparison to the experimental findings. A good agreement was obtained between the numerical predictions and experimental data for the load and energy histories as well as for the maximum impact load, maximum displacement, and contact time. The use of the mass-scaling technique was successfully implemented, reducing considerably the computing cost of the solutions. The maximum load, maximum displacement, and contact time are negligibly affected by the choice of finite element mesh discretization. However, it has an impact on the initiation and progression of interlaminar damage. Therefore, to accurately compute delamination, its correct definition is of upmost importance. The validation of these finite element models opens the possibility for further numerical studies on of woven composite shells and enables shortening the time and expenses associated with the experimental testing. [ABSTRACT FROM AUTHOR]

A new sleeve device has been introduced with the aim of enhancing the performance of steel structures under extreme loading conditions. Previous research has primarily focused on numerical simulations of this sleeve's application, emphasizing the need for further investigation to validate its effectiveness. This research paper presents a numerical analysis that explores how the sleeve device influences the deformation capacity and strength of a bolt up to the point of failure. The study involved the use of a T-stub connection with multiple sleeves, each featuring different geometric parameters. To assess the impact on strength and deformation capacity, a comparison was drawn between these findings and the behavior of a T-stub bolted connection without using the sleeve. In addition, Finite Element (FE) models were employed for additional parametric studies. The test outcomes demonstrated a substantial increase in the deformability of the bolted connection when utilizing the sleeve device, all the while preserving the strength and initial stiffness of the bolts. This proposed sleeve method in the study significantly enhances the connection's capacity by delaying bolt failure. [ABSTRACT FROM AUTHOR]

In this paper, the authors present an extension of the scope of the previously conducted research to the full three-dimensional computer simulation (using the finite element method), which takes into account the interaction between: heavy caterpillar tracks system - working platform - weak subsoil. The article presents a computer model considering two caterpillars, resting on elastic-plastic sub-soil, with standard Mohr-Coulomb yield conditions, allowing for computer simulation of the behavior of the system up to achievement of ultimate limit state. The results of the above model are treated as the reference for a simplified Analytical Models of estimating the limit state, which might be used in design procedures. In turn, these Analytical Models are enhancements of previously presented one. The most important results concluding form the Analytical Model are simple interaction formulas, in the space of moments acting on the machine-subsoil system, limiting a domain of safety in given soil conditions. [ABSTRACT FROM AUTHOR]

Calcium (Ca 2 + ) signals have a crucial role in regulating various processes of almost every cell to maintain its structure and function. Calcium dynamics has been studied in various cells including hepatocytes by many researchers, but the mechanisms of calcium signals involved in regulation and dysregulation of various processes like ATP degradation rate, IP 3 and NADH production rate respectively in normal and obese cells are still poorly understood. In this paper, a reaction diffusion equation of calcium is employed to propose a model of calcium dynamics by coupling ATP degradation rate, IP 3 and NADH production rate in hepatocyte cells under normal and obese conditions. The processes like source influx, buffer, endoplasmic reticulum (ER), mitochondrial calcium uniporters (MCU) and Na + /Ca 2 + exchanger (NCX) have been incorporated in the model. Linear finite element method is used along spatial dimension, and Crank-Nicolson method is used along temporal dimension for numerical simulation. The results have been obtained for the normal hepatocyte cells and for cells due to obesity. The comparative study of these results reveal significant difference caused due to obesity in Ca 2 + dynamics as well as in ATP degradation rate, IP 3 and NADH production rate. [ABSTRACT FROM AUTHOR]

Groundwater plays an essential role in stabilizing underground structures. However, hydrostatic uplift forces from groundwater can create safety hazards. This paper obtained the groundwater buoyancy reduction coefficients of 36 types of clays through model tests and conducted a finite element simulation to obtain the buoyancy reduction coefficients of additional clays with varying soil properties. Machine learning methods, including extreme gradient boosting (XGBoost) and random forest (RF) algorithms, were used to analyze and identify the soil parameters that have a significant impact on the reduction of groundwater buoyancy. It was found that the permeability coefficient and saturation are the primary factors that influence the reduction of groundwater buoyancy. Additionally, the prediction models developed by XGBoost and RF were compared, and their accuracy was evaluated. These research findings can serve as a reference for designing underground structures that can withstand the potential risk of buoyancy in clay. [ABSTRACT FROM AUTHOR]

Micro-Electro-Mechanical System (MEMS)-based pressure sensors operating on the principle of piezoresistivity have found profound application in various fields like automobile, aerospace, aviation, biomedical and consumer electronics. Various research studies have been conducted to optimize the design of MEMS-based pressure sensors to meet specific requirements of different fields. Modification in the structure of the piezoresistors placed on these sensors has shown great effect in this regard. However, most of these improvements have been validated through fabrication and measurement, but there has been a lack of significant studies developing analytical models to explain these improvements. This paper studies the performance of a single-turn piezoresistor design on a square silicon diaphragm. The analytical model relates the dimensions of the single-turn piezoresistor on a square diaphragm to the output voltage, and hence, sensor sensitivity is laid out. The correctness of the relation is also validated through Finite Element Analysis (FEA) performed using COMSOL Multiphysics software. Hence, an optimized single-turn design is presented which achieves a sensitivity of 203.57 mV/V/MPa over a pressure range of 0–1 MPa. These results are then compared to work from existing literature. The comparison shows an improved performance which was achieved by optimizing the design through its derived analytical model. The proposed sensor can be utilized in disposable blood pressure measurement system where high sensor sensitivity is required. [ABSTRACT FROM AUTHOR]

This paper describes the use of cold and hot composite forming technology to produce pointed curtain wall profiles. An electromagnetic–temperature coupling model was constructed using ANSYS to study the temperature and electromagnetic field distribution during the forming process. Numerical simulation was used to optimize the process parameters to obtain the optimum heating parameters with a current of 4000 A, a frequency of 35 kHz, and a duration of 2 s. The accuracy of the model was also verified through experiments. The simulation results show that the use of a conductive magnet can improve the induction heating efficiency, increasing the heating frequency and the temperature peak; however, it also increases the temperature difference. Sharp-corner curtain wall profiles were successfully produced using the optimized process parameters. The temperature of the heating zone was measured using an infrared thermal imager, and the relative errors between the maximum heating temperature obtained from the simulation and the actual measured values were 5.37% and 5.02%, respectively, indicating that the finite element model performs well in terms of prediction. [ABSTRACT FROM AUTHOR]

The flow pattern and transient response of a spinning cylinder partially filled with fluid are investigated in this paper. A two-dimensional finite element model of the fluid domain in the cylinder cavity is developed via the structured tetrahedral element. By using the volume of fluid model, the flow pattern of the liquid is examined numerically. Also, the effects of fluid type, rotating speed, and liquid height on the flow pattern are investigated. Then, the obtained fluid pressure exerted on the inner wall of the cylinder is considered as the input load, and transient dynamic analysis of the spinning liquid-filled cylinder is carried out. Finally, a comprehensive parametric study is conducted to evaluate the effects of liquid type, spinning speed, and fluid height on the dynamical behavior of the system. The results show that these parameters greatly influence the fluid flow pattern and dynamic characteristics of the spinning liquid-filled cylinder system. [ABSTRACT FROM AUTHOR]

In this paper, a new type of large-cavity two-anvil ultra-high pressure die structure is proposed to solve the problem that the large-scale of the two-anvil ultra-high pressure die is limited by the difficulty in machining the large-size tungsten carbide. The die is mainly composed of an internal split cylinder with an inner cone and its support ring and the external steel wire winding layer. The stress distribution and cavity dimensional stability of the split cylinder are studied by using the finite element method and compared with those of the integral cylinder. This suggests that although the cavity-dimensional stability of the split ultra-high pressure die is reduced, the split ultra-high pressure die has greater advantages in improving the pressure-bearing capacity, processing, and manufacturing. [ABSTRACT FROM AUTHOR]

Fracture networks within hot dry rock (HDR) geothermal reservoirs are complex, and heat extraction via water injection is thus a coupled process of heat-fluid-solid multifield. In this paper, utilizing the theory of normally distributed random functions, we develop a corresponding pre-processing subprogram to establish a discrete network model of complex fracture distribution in HDR reservoirs; then construct a heat-fluid-solid finite element model for heat extraction via water injection and compare the numerical solution with the analytical solution of the one-dimensional non-isothermal consolidation problem for verification. The numerical simulation results show that the main factors affecting the heat extraction efficiency of HDR reservoirs include fracture width, fracture density, fracture permeability, and matrix permeability. When a HDR reservoir is injected with water for heat extraction, there is a certain threshold value of these influential parameters, beyond which the outlet temperature drops significantly, resulting in an obvious thermal breakthrough. When injecting water for heat extraction, the values of these parameters should be controlled and kept at a reasonable level, otherwise, the HDR reservoir may enter a thermal breakthrough stage in advance, which is not conducive for long-period heat extraction. Influenced by the random distribution of complex fractures, the leading edge of the cold front may present an irregular distribution. During the process of heat extraction, the stress gradually changes from a compressional state to a tensile state, which induces further damage to the HDR reservoir. [ABSTRACT FROM AUTHOR]

This paper examines the dynamic performance of the pantograph passing through an overlap section of the catenary system, using a China's high speed railway with the 4-span overlap as an example. The pantograph and catenary system are simulated as a lumped mass model and finite element model, respectively. The model is verified according to EN50318:2018. The model is also assessed against an experimental study of the contact force and uplift of contact wire at 300 km/h. Then the contact force and uplift of contact wire at the speed of 150–350 km/h are calculated. The research shows that when the pantograph passes through the overlap, the maximum contact force increases beyond 14%, the standard deviation of the contact force increases by more than 26%, and the increase of the vertical displacement exceeds 38%, which becomes more apparent with the increase of speed. Under the influence of aerodynamic force, when the running speed increases from 150 to 350 km/h, the mean contact force in the knuckle-downstream and knuckle-upstream orientation increase by 59.49% and 97.85%, respectively. As a result, the contact force and vertical displacement increase greatly when passing through the overlap section, which could affect the current collection quality. [ABSTRACT FROM AUTHOR]

The purpose of the paper was to design geometric models of the movable connection made of brass for three different attachment options and three different loads. The numerical analysis of the mechanical properties, stresses, strains and displacements using the finite element method was carried out in SolidWorks 2020 and their comparative analysis was performed. The computer simulations performed will allow the boundary conditions that directly affect the mechanical properties of the engineering materials to be optimised [ABSTRACT FROM AUTHOR]

The paper presents the results of theoretical studies of the force parameters of thick-sheet blanks rolling in relief rolls. Empirical dependences were obtained to determine the average rolling pressure and force. When studying the pressure, the approach of replacing the deformation scheme with a flat analog was used. In the analysis of the force, the finite element method was used to determine the geometric parameters of the deformation zone. Verification of the obtained dependencies was carried out by comparison with the results of computer simulation. Comparative analysis showed high convergence of the calculation and simulation results, as well as the possibility of applying the formulas obtained not only for symmetrical rolling or for speed asymmetry, but also in the case of rolling in relief rolls of different diameters. [ABSTRACT FROM AUTHOR]

The mechanical properties and fracture mechanism of quasi-brittle materials are considered to be largely reliant on the mechanical properties of meso-components and the structure formed when these components are combined. In recent numerical simulation practice, a trend has developed whereby the real structure of materials is considered in as accurate a way as possible. In this paper, the macroscopic and mesoscopic bending behaviours of steel fibre-reinforced reactive powder concrete (RPC) slabs with fibre volume content between 0.0% and 2.5% were investigated using both experimental tests and numerical simulations. Images obtained from X-ray computed tomography (CT) were input into a program named RFPA3D-CT to build a modified three-dimensional finite-element method model. The results indicate that the steel fibres can help to convert a brittle failure pattern of RPC into a ductile one. Compared with specimens without fibres, the crack tortuosity and bending strength of specimens with fibre content of 2.5% are increased by 20.25% and 308.80%, respectively. The bending performance according to numerical results obtained by the modified model are in good agreement with the experimental results. Moreover, the acoustic emission (AE) parameters and AE curves obtained in RFPA3D-CT can be used to reveal the initiation and propagation process of cracks in RPC. [ABSTRACT FROM AUTHOR]

Conformal contact is a commonly presented contact form in assemblies. Non‐proportional loading is the main characteristics of conformal contact, which leads to prominent difficulty in revealing fretting crack behavior. In this paper, a finite element prediction model for Ti‐6Al‐4V pin‐hole contact fretting fatigue crack initiation was developed, which simultaneously considered the effect of fretting wear, surface roughness, surface skewness, surface kurtosis, and residual stress. The results show that phase differences of stress component, change in direction of principal stress, and high stress gradient are the main reasons for the initiation of fretting fatigue under conformal contact condition. The model based on the Fatemi–Socie (FS) parameter successfully predicted the location, orientation, and fatigue life of crack initiation, which agrees well with the experimental results. Additionally, machining‐induced residual stress can effectively inhibit mode I crack initiation at valleys. Moreover, ignoring the surface microgeometry characteristics reduces the prediction accuracy of the crack behavior. Highlights: Surface microgeometry characteristics and residual stress were considered.Residual stress has less effect than roughness on conformal contact fretting fatigue.Consideration of surface geometry significantly improves the prediction accuracy.The predicted results are in good agreement with the experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a novel framework combining the state-based peridynamics (SBPD) with the extended finite element method (XFEM) for crack propagation in two-dimensional solids. Numerical examination is conducted fulfilling both the quasi-static and time-dependent loading conditions. The computational domain is partitioned into two regions: (a) SPBD region: the vicinity of crack tips and potential region where the crack is likely to propagate, and (b) XFEM region: the area behind the crack tip and the rest of the body. The salient features of the developed framework include: (a) avoiding requirement of a priori knowledge of enrichment functions like the conventional XFEM; (b) without fracture criteria for crack propagation; (c) no restriction on the value of Poisson's ratio like the bond-based peridynamics; and (d) higher computational efficiency than the pure peridynamics. The efficiency and accuracy of the proposed framework are systematically demonstrated through benchmark examples involving quasi-static crack growth and dynamic crack branching problems. [ABSTRACT FROM AUTHOR]

This paper summarizes the results of a numerical simulation and subsequent variability analysis of the lateral load-resisting behavior of unbraced and chevron-braced glulam portal frames. Longitudinal tension/compression strengths of each glulam member were determined based on wood-size effect theory. The finite-element method (FEM) and an experimental study were carried out to determine the nonlinear mechanical behavior of glulam braces and bolted glulam beam-to-column connections. OpenSees "Pinching4" hysteresis models were adopted to model the mechanical behavior of both glulam braces and bolted beam-to-column connections. An FEM model of the glulam frames was developed to predict the lateral load-resisting hysteretic response of such frames. The stochastic finite-element method was used to calculate the frame capacity considering random distributions of connection and brace capacity. The FEM model presented can represent the nonlinear and hysteretic pinching behavior of an unbraced glulam frame whose behavior is dominated by splitting in the connection regions. Similarly, the strength softening and stiffness degradation of a chevron-braced glulam frame was also captured. Response surface method analysis was used to regress braced frame capacity from 200 analyses to a single set of capacity variables. The approach described in this paper demonstrates promise for optimizing the industrial-scale production of glulam portal frame structures. [ABSTRACT FROM AUTHOR]

The annual drift of ÎĽ Gal level is an important indicator of superconducting gravimeters, which helps geophysicists to clarify the weak geophysical signals. In this paper, a finite element simulation model of the superconducting gravimeter sensor is developed based on the H formulation for evaluating the contribution of the excitation AC losses and the AC losses under operating conditions to the superconducting gravimeter’s drift. The model combines the H formulation and the heat transfer module of COMSOL Multiphysics software to calculate the AC losses of the superconducting gravimeter’s test mass and obtain the distribution images of the test mass’s temperature due to the AC losses-induced heating. The overall temperature rise of the test mass is obtained by assuming that it heats up uniformly and thus combines the temperature dependence factor (10 ÎĽ Gal mKâˆ'1) of the superconducting gravimeter to derive the instrument drift induced by AC losses. Then, the long-term drift due to excitation losses can reach 0.847 ÎĽ Gal yrâˆ'1, while the operating losses can be 0.45 ÎĽ Gal yrâˆ'1 or even less, according to the simulation. In addition, this paper discusses the effects of the parameters (index number, critical electric field, and critical current density) in the Eâ€"J power law introduced by the H formulation on the AC loss evaluation. It is concluded that the AC losses are sensitive to the critical current density, and increasing the test mass’s critical current density helps enhance the stability of the superconducting gravimeter. [ABSTRACT FROM AUTHOR]

With the increasing requirements of automotive lightweighting, metal/CFRP laminates are increasingly used. In this paper, Al/CFRP laminates were prepared using an integrated hot press curing method, and the optimum curing conditions were determined using the single-lap shear test at 130 °C for 45 min. The effects of fiber lay-up, forming speed, and metal layer thickness on bending springback were investigated using the V-shaped bending test and Abaqus finite element analysis method. The results show that fiber lay-up has an important influence on springback. Among the five different fiber lay-ups (0° unidirectional, 90° unidirectional, 0° orthotropic, 90° orthotropic, and 45° orthotropic), the 45° orthotropic lay-up had the lowest springback rate of 1.11%. Increasing the thickness of the sheet metal can significantly reduce the resilience rate. As the sheet thickness increased from 2 mm to 3 mm, the springback of the 90° unidirectional lay-up decreased by 43%. Springback was not sensitive to forming speed, and the difference in springback was within 1% at different forming speeds. The damage behavior of the forming process was analyzed using the three-dimensional Hashin damage law with the Vumat subroutine and microscopic analysis. Fiber and resin damage under 45° orthotropic lay-up conditions was relatively small compared to fiber damage under 0° unidirectional lay-up and resin damage under 90° unidirectional lay-up. [ABSTRACT FROM AUTHOR]

Cast steel nodes are widely used as important components of offshore platform, owing to their better performance than welded nodes. In this paper, the mold filling and solidification process of cast steel nodes were numerically simulated and verified by the finite element analysis commercial software package—ProCAST, and the occurrence of shrinkage porosity was quantitatively predicted based on the simulation results. The numerical simulation results of the preliminary design showed that the overall filling was stable with bottom gated system, agreeing well with the design requirements. However, the shrinkage porosities in the intersection of lower tubes and main tube were evident due to the insufficient feeding. Optimization of the casting design was carried out through repeated computer simulation. By incorporating chills in the cores, the optimized design showed that the shrinkage porosities in the intersection of lower tubes and main tube were effectively eliminated. In view of these aforementioned optimizations, the casting steel can meet the technical requirements in an actual production. [ABSTRACT FROM AUTHOR]

Biological structures possess excellent damage tolerance, which makes them attractive for ballistic protection applications. This paper develops a finite element modelling framework to investigate the performance of several biological structures that are most relevant for ballistic protection, including nacre, conch, fish scales, and crustacean exoskeleton. Finite element simulations were conducted to determine the geometric parameters of the bio-inspired structures that can survive projectile impact. The performances of the bio-inspired panels were benchmarked against a monolithic panel with the same 4.5 mm overall thickness and projectile impact condition. It was found that the biomimetic panels that were considered possessed better multi-hit resistant capabilities compared to the selected monolithic panel. Certain configurations arrested a fragment simulating projectile with an initial impact velocity of 500 m/s, which was similar to the performance of the monolithic panel. [ABSTRACT FROM AUTHOR]

With the excavation of underground opening, the roof rock block may fall under external dynamic disturbance. In this paper, the roof rock mass was simplified as a rock block system composed of trapezoidal rock blocks. A series of experiments and numerical simulations were performed to study the sliding process of the key block under the horizontal static clamping load and vertical impact disturbance. The propagation of stress wave in the block system were captured and analyzed by using high-speed camera and digital image correlation technique. The results reveal that a pendulum-type wave was generated due to the propagation and superposition of stress waves in the block system. Therefore, the governing mechanism of the sliding displacement of the key block was clarified based on the propagation of incident stress waves or pendulum-type waves. Meanwhile, it is found that the sliding distance of the key block decreases in a power function with the increasing friction coefficient, or decreases in a parabolic function with the increasing trapezoid internal angle. Finally, a case study on the roof block sliding of the roadway at a gold mine was conducted, and it is concluded that the sliding of the key block resulted from the coupled effects of "shear driving" and "low friction" driven by stress wave propagation, regardless of a single or multilayer rock block system. These results may provide technical guideline for preventing rock-falling accidents caused by blasting disturbances in underground mining. [ABSTRACT FROM AUTHOR]

Focusing on the phenomenon of the crack on the autoclave flange, a three-dimensional model of the autoclave was established based on the Ansys Workbench platform. A new finite element analysis flow for optimizing the design of autoclave teeth was established using the Fluent, Static Structure, and Direct Optimization modules. The paper analyzed and discussed the maximum stress and minimum fatigue life at the corresponding position. The variation trend of stress and fatigue life at the corresponding position after fillet optimization was also discussed. The results showed that the equivalent stress of autoclave teeth without fillet optimization reached the maximum under different fillet sizes. The equivalent stress and fatigue life of the autoclave tooth were the same as the rounded corner size obtained by the optimization design. The optimal global solution could be obtained through the optimization design process. [ABSTRACT FROM AUTHOR]

In order to study the die wear law of rotary fine blanking helical cylindrical gear, a three-dimensional rigid plastic finite element model of rotary fine blanking helical cylindrical gear is established on the Deform-3D software platform. Based on the Archard wear model, this paper analyzes the die wear in the fine blanking process, obtains the wear distribution of each point on the working surface of the die, determines the maximum wear area, and makes a comparative analysis with the fine blanking die wear of spur gear. Through the single factor variable method, this paper studies the effects of reverse jacking force, blank holder force, blanking speed, punch and die clearance, die fillet radius, and die initial hardness on die wear. The test results show that when the punch reduction is the same, the wear of the female die of fine blanking helical cylindrical gear is greater than that of fine blanking spur cylindrical gear. When the counter jacking force increases from 100 kN to 200 kN, the maximum wear of the die gradually increases from 6.91 × 10–6 mm to 9.38 × 10–6 mm; when the blank holder force increases to 3/4 of the blanking force, the die wear decreases with the increase of blank holder force; it is ideal when the blanking clearance is 0.5% t (0.02 mm). Conclusion. The wear model can accurately predict the relationship between main process parameters and wear in the process of rotary fine blanking, and the measures to reduce die wear are put forward from the aspect of process design. [ABSTRACT FROM AUTHOR]

This paper proposes a new flexible and microscale roll gap control technology to obtain a stronger strip flatness control ability. According to the principle of microscale roll gap control technology, an electromagnetic control rolling mill with the function of roll profile control and large diameter ratio rolling is designed and built. To analyze the flatness control ability, a comprehensive finite element model (FEM) is established, and an indentation experiment and a rolling experiment are carried out. The simulation results show that under different rolling forces and tensions, the average quadratic crown control ability is more than 40 μm, and the average quartic crown control ability is more than − 3 μm. The control ability increment of the quadratic crown is greater than that of the quartic crown. In the indentation experiment, a stable roll profile can be achieved by PID control after reaching the target roll profile. Increasing the regulation amount can change the strip crown from positive to negative. Even under high rolling force conditions, microscale roll gap control technology can also realize a strip crown adjustment of 19.5 to 0.5 μm. Moreover, this technology can adjust the strip shape from edge waves to non-waves and middle waves in the rolling experiment. In this paper, the feasibility of using this technology to adjust the roll gap shape has been verified, and we demonstrate that the roll gap control goal of uniform transverse size distribution can be achieved. [ABSTRACT FROM AUTHOR]

With the progressive promotion of BIM technology in collaborative design and engineering data management, there are large amounts of project information available for intelligent construction, engineering computation and design optimization. In the construction of subway station, BIM technology is still not mature and the engineering design is generally separate from the engineering safety evaluation. Thus, this paper proposed a technology that integrates BIM and numerical simulation (BIM-FEM/FDM integrated technology) to solve the problem of separation between engineering design and computation. A three-dimensional parametric modeling of subway station excavation was first carried out using the Revit® modeling software. Afterward, a FEM/FDM-process oriented data conversion interface was developed to extract and process the critical information from the parametric BIM model for numerical simulation. Then, under the impetus of an auto-simulation interface, the safety evaluation of subway station excavation was realized automatically and visualized graphically. The research of the BIM-FEM/FDM integrated technology presented in this paper has established a supporting platform to achieve the integration of BIM-based design and safety evaluation for subway station excavation. [ABSTRACT FROM AUTHOR]

In order to deal with the bottleneck of poor plasticity and low formability of magnesium alloys at room temperature, a numerical simulation and a die process optimization method based on hot stamping of AZ series magnesium alloys were proposed. Firstly, based on the PAM-STAMP finite element analysis platform, the thermomechanical coupling numerical simulation is carried out for the cross cup-shaped deep drawing, and the changes in the stress and temperature field during the forming process are analyzed. Aiming at the influence of various process parameters on the plastic formability of magnesium alloys, the effects of sheet metal shape, die fillet size, friction factor, and blank holder force on the forming quality were analyzed through experiments. The experimental results show that under the same conditions such as temperature and blank holder force, the numerical simulation method and the mold process optimized in this paper can be used to form parts that are 25% deeper than the traditional process, and the sheet material can be thinned to the maximum at this time. The amount is 0.152 mm, which verifies the correctness and superiority of the method and process in this paper. [ABSTRACT FROM AUTHOR]

The paper presents the numerical simulation of quenching cylindrical steel sample immersed in three different quenchants: water, 5 % aquatensid solu- tion, and isorapid oil. The quenching process starts from the initial temperature of the cylinder at 850 °C and moves through the air until it reaches the quenching bath. The quenchant is held at constant temperature of 40 °C. The cylinder is made of carefully selected steel which does not change its structure during quenching and heating. Cylindrical samples were manufactured in three different dimensions (R, H), (mm): (12.5 x 100), (25 x 150) and (37.5 x 225), so that four measuring points were installed in each sample. Each measuring point consists of thermocouple installed beneath the cylinder surface, capable of measuring the temperature every half second. Based on the experiment, the numerical simulation is recognized as transient and nonlinear two-dimensional heat conduction problem consisting of the two main tasks: direct heat transfer problem (DHTP) and inverse heat transfer problem (IHTP). The paper proposes a new multi-objective optimization approach for the estimation of heat transfer coefficients during the numerical simulation of quenching cylindrical steel sample. The proposed approach gained better results and less convergence time compared to the results from the literature. The paper includes methods, algorithms and the source code for the calculation of the temperature fields in time and heat transfer coefficient estimation of the IHTP. The simulation software has been implemented in C# programming language and can be found at http://github.com/bhrnjica/quenching_simulation. [ABSTRACT FROM AUTHOR]

To solve the problem of poor anti-impact performance of plane-cutter bit under the condition of shallow and high ROP (rate of penetration) in Liaohe Oilfield, this paper studies the rock-breaking mechanism of axe cutter under the former condition. In this paper, the finite element method is used to establish the rock-breaking model with high ROP. Numerical simulation is used to study the stress and failure mode of rock. Based on the results of numerical simulation, the laboratory tests of axe cutter have been carried out to explore the magnitude and fluctuation of tangential force. Field application shows that the axe cutter is obviously better than plane cutter in anti-impact performance, total footage and ROP. The results show that the axe cutter mainly relies on plowing and tensile shear to break the rock so that the tangential force and its fluctuation are smaller than those of the plane cutter, which means the impact force is smaller. Its impact resistance is better; the service time of the bit is longer. The axe cutter bit has more advantages than the plane-cutter bit, such as more adapting to the working condition of shallow and high ROP and increasing drilling efficiency. [ABSTRACT FROM AUTHOR]

Mass Spring Systems (MSS) are often used to simulate the behavior of deformable objects, for example in computer graphics (modeling clothes for virtual characters) or in medicine (surgical simulators that facilitate the planning of surgical operations) due to their simplicity and speed of calculation. This paper presents a new, two-parameter method (TP MSS) of determining the values of spring coefficients for this model. This approach can be distinguished by a constant parameter which is calculated once at the beginning of the simulation, and a variable parameter that must be updated at each simulation step. The value of this variable parameter depends on the shape changes of the elements forming the mesh of the simulated object. The considered mesh is built of elements in the shape of acute-angled triangles. The results obtained using the new model were compared to FEM simulations and the Van Gelder model. The simulation results for the new model were also compared with the results of the bubble inflation test. [ABSTRACT FROM AUTHOR]

Considering the stringent requirement of the pointing accuracy up to 2.5″ of the world's largest full steerable radio telescope, this paper studies the welding experiment of the azimuth track of the antenna. First, the opposite deformation jig and welding process were designed for the QTT's azimuth track. Then, the welding process was numerically simulated using a finite element model. The simulation results show that a better welding effect will be obtained by appropriately reducing the opposite force on the basis of the original. The three deformation processes of the track are regulated by the opposite deformation jig. The results show that the opposite deformation jig designed for QTT's azimuth track can make the amount of deformation and flatness meet the design requirements. Finally, nondestructive testing was carried out to check the welding quality of the track surface and interior. The results show that there are no obvious defects in the welds of the azimuth track. The constraint jig and welding processes designed for QTT are effective and feasible. [ABSTRACT FROM AUTHOR]