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Ductility deficiency in reinforced concrete (RC) piers is a substantial factor contributing to earthquake damage in bridge structures. In this study, the conventional concrete in the potential plastic hinge area was substituted with polypropylene fiber-reinforced engineered cementitious composite (PP-ECC), thereby leveraging its high ductility characteristics to explore the seismic performance of RC piers strengthened by PP-ECC. A finite element model was established to discuss the reinforced height, axial compression ratio, longitudinal reinforcement ratio and stirrup ratio on the hysteresis performance by referring to a published paper with a 1/5 scale test specimen. Based on the results of the parameter analysis, an ideal set of configuration parameters was proposed. Subsequently, a full-size simplified mechanical model was established with ideal reinforcement parameters. Time-history and pushover analysis were utilized to test the seismic response. The study indicates that the two analytical methods were largely consistent. The improvement in the displacement and shear force of the strengthened pier gradually decreased with the increase in acceleration amplitude. Time-history analysis reveals a decrease in the enhancement of displacement from 82.26% to 17.98% and a reduction at the bottom reaction from 12.2% to 1.5%. Under the pushover analysis method, the retrofitting level of the top displacement decreased from 77.22% to 11.53%, whereas the improvement level of the bottom shear decreased from 9.62% to 3.69%. These results provide a theoretical basis and reference standard for the application of PP-ECC.

Compared to steel structures, aluminum alloy structures are more susceptible to fire damage. Accurately evaluating the residual bearing capacity of fire-damaged aluminum alloy members is crucial for effective post-disaster management. Therefore, this paper investigates the post-fire bearing capacity of I-shaped aluminum alloy members under axial compression. First, a post-fire test on 16 I-shaped aluminum alloy members under axial compression was carried out. The test results indicate that all specimens fail by the minor axis flexural buckling, and the bearing capacity of the specimens decreases with the increase of the slenderness ratio. Moreover, a trilinear relationship is found between bearing capacity and post-fire temperatures. Second, finite element (FE) models are established using ABAQUS and validated against the test results. Subsequently, numerical analysis is carried out, considering various aluminum alloy brands, post-fire temperatures, slenderness ratios, initial geometrical imperfections, and cross-section dimensions. Through the statistical regression technology and the introduction of strength and stability-bearing capacity reduction coefficients, the formulae for estimating the post-fire stability-bearing capacity of I-shaped aluminum alloy members under axial compression are derived. Finally, the proposed formulae are verified to be accurate through error analysis.

A comprehensive examination was performed on cold-formed steel (CFS) built-up battened columns constructed from lipped angles subjected to axial compression. The study looked at steel grade, column thickness, and cross-sectional angles. The finite element models developed using the ABAQUS software included material nonlinear behavior, geometric imperfections, and detailed modeling of connections to simulate actual behavior as accurately as possible. Numerical models have been compared with available experimental data to verify their accuracy and reliability. Among the foregoing, the most critical parameters are steel grade, column thickness, and geometry of the cross-sections. Numerical results confirm that increasing column thickness and higher steel grades result in a significantly larger axial load-carrying capacity and stability improvement of the columns. Furthermore, the cross-sectional geometry of angle sections plays a crucial role in mitigating local buckling and ensuring the overall structure performs well. These findings have enabled optimization in the design of CFS-built-up battened columns, and they have also provided practical guidelines for practicing engineers to design and develop safer and more efficient structural systems. This research demonstrates that these aspects are critical in achieving optimality in CFS structures, particularly for axial compression. The numerical results showed that the cross-sectional shape, steel grade, and thickness influenced the ultimate load capacity. Specifically, Shape S18, with a thickness of 1.95mm and G450 grade steel, developed the maximum ultimate load, which was 335.85% higher than the general average. The G450 steel grade performed better, raising the load-carrying capacity by 82.65%, while an increased thickness up to 1.95mm increased the same by 75.91%. These results emphasize the importance of choosing optimal parameters to maximize structural performance.

Socket-shield technique expands the indications for immediate implant placement and effectively maintains the contour of the labial bone. However, due to its relatively high incidence of complications, the technique has not become routine. Understanding the biomechanical characteristics among different structures in socket-shield technique has clinical significance. In this study, finite element analysis was conducted to investigate the biomechanical correlations with the exposure, migration and fracture of the root shield. Seven three-dimensional finite element models were constructed with jumping gaps of 0mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm and 3mm, respectively. The results illustrate deep overbite loading induces unfavorable biomechanical reactions in various structures in socket-shield technique. For normal occlusion, the jumping gap that is too small leads to stress exceeding the yield strength of the root shield and comparatively large displacement in the root shield, possibly causing fracture and migration of the root shield. The jumping gap that is too large causes micro-damages to the cortical bone around the implant, potentially leading to cortical bone resorption and exposure of the root shield. Therefore, the technique should be avoided in patients with deep overbite loading, and the jumping gap of 1.5–2mm may be a suitable choice.

Soft subgrade poses significant challenges to the designer of railway tracks due to its high compressibility and low shear wave velocity. The low shear wave velocity might affect the maximum design speed of the train. The stabilization of this soft soil improves its performance and reduces the expected settlement. However, little attention has been paid to understanding the feasibility of different stabilization techniques, as there are very few studies on this topic. Thus, this research study aims to determine the impact of granular trench reinforcement of soft subgrade on the dynamic response of a railway track subjected to a moving train load. Three-dimensional finite element analysis has been used in this research. The effect of the train speed and the depth of the granular trench has been carefully evaluated. It has been found that the critical velocity (which is the velocity that corresponds to the highest settlement) is not affected by the granular trench reinforcement. In addition, it has been noted that the granular trench reinforcement reduces the maximum settlement of the railway track under the moving loads, with a percentage reduction ranging between 1% and 24%. Furthermore, the granular trench reinforcement did not affect the acceleration induced in nearby areas due to the train’s vibration. The results of this research provide useful insight into the feasibility of the granular trench and help design engineers compare different solutions for the problems of soft subgrade soil.

This paper presents a comprehensive investigation into the interference effects of three moving trains on railway tracks using three-dimensional (3D) finite element analysis. The primary focus is on understanding the behavior of the middle train and its settlement characteristics when influenced by two neighboring moving trains. To establish a baseline, the study also includes an analysis of a single train. The train speeds considered in the analyses range from 100km/h to 450km/h, and the spacing between trains ($S$) varies across 10 values from 1m to 10m. The results reveal intriguing patterns in the settlement behavior of the middle railway track. Specifically, the interface significantly impacts settlement, causing a decrease for $S=1$m compared to a single railway track and a subsequent remarkable increase for larger $S$ values. This conflicting behavior arises from the combined effects of confinement and vibration induced by neighboring trains. Moreover, as the spacing between trains increases, the interference effect diminishes due to a decrease in vibration. Quantitative findings include an average percentage difference in the maximum settlement ranging from −16% to $+$109%, with the interference effect decreasing as S increases. The critical speed of the middle train’s railway track is also influenced by interference, exhibiting a change from 300km/h to 350km/h for $S$ values of 2–6m. This highlights the necessity for special attention to interference effects in the design stage, particularly regarding critical speed considerations. The study contributes valuable insights into the complex dynamics of three moving trains on railway tracks, offering practical implications for railway track design and ensuring safe and efficient operations.

Structure of a MEMS based Capacitive Accelerometer has been analyzed in this paper. The symmetrical beam-mass structure with different interconnection has been investigated using Finite Element methodology. The simulation model is calibrated with the existing structure of H-shaped beam capacitive accelerometer. Then a rigorous simulation and analysis is carried out to propose new beam structure with improved sensitivity. Analytical model has been evaluated using MATLAB software. Output voltage of the device for a given acceleration is calculated and sensitivity of the device is also analyzed. To improve sensitivity of the device, two new connector structures such as Z-shaped beam and Ω-shaped beam capacitive accelerometer has been proposed. For a particular acceleration, displacement of the proof mass with new structures is increased almost 57% and 66% and the sensitivity has been improved from 7.71pF/g to 13.0pF/g and 13.8pF/g respectively. Parametric optimization of the Ω-shaped beam capacitive accelerometer has also been described for further improvement of device performance.

This study highlights the development of an intelligent thermo-structural model for precise prediction of responses such as the width of heat-affected zone (HAZ), equivalent stress and total deformation for laser beam machining (LBM) process while machining a novel Dual Phase 780 (DP780) workpiece. The numerical model is analyzed through response surface Box–Behnken design to study the consequences of input parameters such as voltage ($V$), current ($I$) and cutting speed ($N$) on the above-mentioned response parameters. The results achieved through the numerical model are validated by comparing them with experimental results. Furthermore, a careful parametric study along with line and surface plot analysis is conducted to evaluate both linear and quadratic relationships between the input and the response parameters, respectively. The results indicate that the HAZ can be reduced significantly through efficient laser processing with optimum input parameters. The process parameters are optimized by developing an objective function for each of the response parameters through regression analysis. An extremum model is used to obtain the ideal values of HAZ, equivalent stress and total deformation. These results are also validated by conducting a confirmative test using the numerical simulation model which is validated through experiments.

We study a model of scalar quantum field theory (QFT) in which spacetime is a discrete set of points obtained by repeatedly subdividing a triangle into three triangles at the centroid. By integrating out the field variable at the centroid we get a renormalized action on the original triangle. The exact renormalization map between the angles of the triangles is obtained as well. The map can be used to find the partition function in scalar field theories in a recursive manner. A fixed point of this map is the cotangent formula in Finite Element Method which is used to find the energy stored in fields on a plane due to a Laplacian.

Sandwich panels can be manufactured in many ways like lamination press, closed mold fabrication, and vacuum bag compaction. During manufacturing, the core and the sheets are attached under certain applied pressure and temperature, associated with a deformation and stress remaining in the sandwich core. This study presents an evaluation of the compressive residual stress effect of the core which occurs during the localized shock loading at the mid-span of a clamped sandwich plate. We simulate such a square lattice core sandwich plate by commercial finite element code, ABAQUS/Explicit. We apply uniform distributed loading on upper face sheet and temperature difference occurred during the manufacturing process is taken here before the impact simulation step. These loadings induce certain amount of residual stresses in core structure of sandwich panel. The computational result from non-residual stress case is verified by comparing with the results of published experimental data on similar investigation. In addition, the effect of existing residual stress at core is analyzed. We also compare the dynamic responses of two clamped sandwich plates with and without pre-stressed core. And impact resistance of sandwich panel is explained in the view of energy capacity. Results show that the shock loading behavior of sandwich panel depends on its manufacturing process and panels with compressive residual stresses have less deformation and high impact energy absorption characteristics.

To participate in Student Formula Society of Automotive Engineers (SAE) competitions, it is necessary to build an impact attenuator that would give an average deceleration not to exceed 20g when it runs into a rigid wall. Students can use numerical simulations or experimental test data to show that their car satisfies this safety requirement. A student group to study formula cars at the Korea University of Technology and Education has designed a vehicle to take part in a SAE competition, and a honeycomb structure was adopted as the impact attenuator. In this paper, finite element calculations were carried out to investigate the dynamic behavior of the honeycomb attenuator. Deceleration and deformation behaviors were studied. Effect of the yield strength was checked by comparing the numerical results. ABAQUS/Explicit finite element code was used.

Dry zinc coating processes similar to the shot pinning was studied in the aspects of environmentally benign process to substitute traditional wet type phosphate coating of the work-piece, which is for protection from the deterioration of the surface quality and the shortening of the lifetime of the die during cold extrusion. Experiment and simulation on the collision and coating process of the zinc coated steel balls onto the steel target was performed. Coating patterns on the target and damage of the zinc shell of the ball with respect to the colliding speed were observed during the experiment. Explicit finite element analysis showed the deformation and the fracture of the zinc shell were similar to the experimental results even though the adhesion of the zinc layer onto the work-piece could not be expressed directly. The optimal velocity of the balls was obtained considering effective zinc coating and maximum lifetime of the ball.

As a next-generation metropolitan transportation means, nowadays non-step bus is in the spotlight world widely. However, in the design of non-step bus, the most important consideration should be focused on the securing of the survival space for passengers in unexpected traffic accident. In this context, this paper presents the finite element analysis of the rollover and head-on crash response of a composite non-step bus. A 3-D full-scale finite element model of the non-step bus, together with the simulation conditions which are consistent with the safety test rules established in Europe, is employed for the realistic and reliable numerical analysis.

In order to shorten the time of through-the-canopy-ejection, and to ensure pilot safely escape and survive. The application of linear cutting technique using miniature detonation cord( MDC) in through-the-canopy-ejection-system is proposed. A series of different kinds of MDC are designed. Firstly experimental study on the cutting process of the PMMA plate wiht MDC is carried out. Material of metal cover explosive types and the range of charge quantities are determined. Consequently the phenomena of spallation is observed, and the relationship between the cutting depth and charge quantities is obtained. For the comparison, the process of explosion cutting PMMA plate is simulated by means of nonlinear dynamic analysis code LS-DYNA. Spallation phenomena which occurs in the experiment, is also observed in the simulation. Simulation results present the relationship of cutting depth of PMMA plate versus charge linear density, which well agree with experimental ones.

This paper is concerned with development of a process map for sequential compression-backward extrusion of bulk AZ31 Mg alloy at the warm temperatures. In experiments, metal flows and crack initiations are carefully investigated and formability is examined systematically for various forming conditions such as forming temperature, punch speed, and a gap between a specimen and die. Then, a process map for the sequential compression-backward extrusion of bulk AZ31 Mg alloy at the warm temperature is proposed. In order to further understand deformation behaviors and damage evolution during warm forming process, thermo mechanical finite element analyses coupled with damage evolutions are carried out. In general, finite element predictions support experimental observation. Finally, it is concluded that the process map, proposed for the sequential compression-backward extrusion of AZ31 Mg alloy, is valid.

Microwire made using a straightening process has high added value and has been adopted in many fields of industry. There is much active research on the straightening process. Very straight microwire can be obtained by removing the residual stress induced during the manufacturing process. Generally, the residual stress is removed or minimized through several drawing steps with heat treatment. This study used finite element analysis to calculate the residual stress during each straightening process and investigated the main reason for a change in stress.

Magnesium alloy sheets are usually formed at temperatures between 150 and 300°C because of their poor formability at room temperature. In the present study, the formability of AZ31B magnesium alloy sheets was investigated by the analytical and experimental approaches. First, tensile tests and limit dome height tests were carried out at several temperatures between 25 and 300°C to get the mechanical properties and forming limit diagram (FLD). A FLD-based criterion considering the material temperature during deformation was used to predict the forming limit from a finite element analysis (FEA) of the cross-shaped cup deep drawing process. This criterion proved to be very useful in designing the geometrical parameters of the forming tools and determining optimal process conditions such as tool temperatures and blank shape by the comparison between finite element temperature-deformation analyses and physical try-out. The heating and cooling channels were also optimally designed through heat transfer analyses.

Backward tube spinning experiment of BT20 (Ti-6Al-2Zr-1Mo-1V) alloy was carried out with an aim to examine texture evolution of titanium alloy in spinning process. The initial texture and the spinning texture were investigated by X-ray diffraction, and deformation history of a single-pass spinning was analyzed using finite element method. Tilt basal texture occurs when thickness reduction reaches a medium level (~ 49% for the outer surface and ~ 58% for the inner surface in the present study) and that further deformation promotes the formation of central basal texture. During early several passes basal texture in the outer surface develops more rapidly and intensely than that in the inner surface due to much larger deformation. However, the maximum intensity of texture in the inner surface reaches a higher level in subsequent passes for the following two reasons: (1) the discrepancy between equivalent deformation in the internal layer and that in the external layer reduces with increasing deformation; (2) material in the inner surface undergoes much smaller transverse shear deformation. Spinning texture is characterized by its asymmetry, which results from asymmetric spinning deformation investigated by analyzing deformation histories of material particles located in the inner and outer surface.

Plastic deformation that occurs in a heavy slab during plane-strain rolling was investigated by the finite element analysis. A cylindrical pore was assumed to be located along the transverse direction of a slab. The effective strain was found to be the largest at the sub-surface layer and the smallest at the middle layer, where the shear strain developed the least. Pore closure was most difficult at the middle layer. This is where hydrostatic stress in addition to effective strain developed the least. Rolling torques, rolling forces and pressure distributions at the roll/slab interface were investigated as well, under various conditions.

The technique of severe plastic deformation (SPD) enables one to produce metals and alloys with an ultrafine grain size of about 100 nm and less. As the mechanical properties of such ultrafine grained materials are governed by the plastic deformation during the SPD process, the understanding of the stress and strain development in a workpiece is very important for optimizing the SPD process design and for microstructural control. The objectives of this work is to present a constitutive model based on the dislocation density and dislocation cell evolution for large plastic strains as applied to equal channel angular pressing (ECAP). This paper briefly introduces the constitutive model and presents the results obtained with this model for ECAP by the finite element method.