Commercial Finite Element Analysis Program Research Articles

An Analytical Study for Safety Evaluation of Demolition-Assembled Permeable Steel Open-Type Erosion Control Dam

Recently, localized torrential rains are occurring worldwide due to global warming and abnormal temperatures, and in Korea, where most of the land is composed of mountainous areas, flood damage such as landslides is continuously increasing. Accordingly, the importance of erosion control dams, one of the structures for preventing flood damage in mountainous terrain, is mentioned, but mostly dams need alternatives due to material limitations composed of concrete. In this study, an improved open-type erosion control dam was studied to reduce the cost of rapid recovery and maintenance based on the problems of the existing erosion control dam consist of concrete. For this purpose, an analytical study using a commercial finite element analysis program was conducted to implement the dam shape and drift prevention structure, and to calculate the external load under extreme environmental conditions to comprehensively confirm the safety of the target structure.

Experimental and Numerical Predictions of Cryogenic Leakages in Welded Steel Plates

This study presented experimental and numerical research to investigate the effect of cryogenic leakage on a plate structure of AH36-grade steel containing welded joints. To simulate the cryogenic leakage conditions, the welded plate was exposed to a temperature of −196 °C by supplying liquid nitrogen (LN2) to the center of the steel plate. The time-dependent temperature history and strain variation were measured by using thermocouples and strain gauges attached to the plate surface. Additionally, the residual stress of the middle surface section before and after the cryogenic leakage process was measured by X-ray diffraction analysis (XRD). A three-dimensional finite element model was created with the use of a commercial finite element analysis (FEA) program to simulate the flux-cored arc welding process and cryogenic leakage process. The steel surface temperature dropped sharply and reached approximately −196 °C at 160 s after LN2 supplement. After the first 650 s of the LN2 leakage experiment, the outside of the trough reached approximately −75 °C and −25 °C, depending on the location of the thermal couples. Although there was a relative difference in the results, the experiment and numerical simulation results for temperature and stress distribution showed good agreement. The results could be utilized in the ship design stage adopting welded structures as a basic database.

음향진동 헬스케어기구의 마사지력 분석을 위한 유한요소해석 및 실험검증

The acoustic vibration health care device is a small medical device that can be used in homes. It was developed for the general public to meet the current needs of modern-day workers who value health and leisure. The device’s massager negates acoustic vibrations set at a certain frequency that activate metabolism and blood circulation. It has also been proven to lessen pain or enhance treatment effects by stimulating the cranial nerves. Stored inside the massager is a voice-coil actuator made of a bobbin core wrapped in coils and a permanent magnet. The component produces the Lorentz force as a result of the applied current and the magnetic flux density form the internal magnetic field. In our experiment, we used the ANSYS Maxwell, a commercial finite element analysis program, to analyze the electromagnetic field. We also measured and compared the Lorentz force by testing the massager’s vibrations. Through these actions, we validate the finite element analysis and obtained the design technology data of the massager model.

A Study on the Influence of Dominant Parameters Related to Brake Squeal in the Brake System with the Flexible Pad

The brake squeal noise is a high-frequency noise over 1 kHz range generated by the contact between the brake pad and the disk. The purpose of this paper was to investigate the behavior of the squeal noise characteristics of the brake system from an instability point of view, according to the variation of major parameters such as friction coefficient between the flexible pad and the disk, brake pressure, and Young’s modulus of disk. Full nonlinear perturbed modal analysis using commercial finite element analysis program was performed to derive complex eigenvalue results of the model. And the sensitivity behavior was observed. Increasing the coefficient of friction or Young’s modulus of disk tended to make the squeal mode of the model more unstable. However, the change in brake pressure has a complicated nonlinear relationship with the squeal mode of the model. The judgment technique conducted in this study should be considered to be used in the design of the vibration point of the disk and pad of railway vehicles in the future.

Lateral Deflection Behavior of Perforated Steel Plates: Experimental and Numerical Approaches

This study aimed to investigate the behavioral characteristics of the lateral deflection of a simply supported perforated steel plate subjected to axial compression. Investigating the lateral deflection of the perforated plate is of great significance because the buckling limit of structural members can be predicted not only by strength but also by displacement (or deflection). For this purpose, we conducted buckling experiments by considering various variables of the perforated plate, such as opening size, thickness, and aspect ratio. In addition, a series of elastoplastic large deflection analyses were performed using the commercial finite element analysis program, and the calculated results were compared along with the experimental results. Finally, practical curves, which can predict lateral deflection with an increase in axial displacement, and the occurrence point of ultimate strength are reported in this study. The results showed that there was a distinct difference in the behavior of lateral deflection between perforated plates with different opening ratios. The local buckling occurred mainly around the opening and was more dominant with an increase in the opening ratio. In addition, the ultimate strength of the perforated plate was determined at the end of the local buckling phase.

Design and Thermal Analysis of High Power LED Light

In the development of lighting technologies, light emitting diode (LED) technology plays an important role due to its high efficiency. LED lightening is the future of indoor and outdoor illumination solutions that all around of the world there is a widespread transition to save energy and have better quality illumination via LED-based solutions. On other hand, cooling of high power LED is crucial factor to utilize LED in high performance. In addition, finned heat sink could not be efficient based on the its geometry and usage areas due to the powder, the rain and the muds effects. In this study, an un-finned heat sink LED armature consisting of aluminum sheet metal was designed using a computer-aided-design (CAD) program. Furthermore, manufacturing of the heat sinks from sheet metal plates with bending machines enables to increase variety of LED armatures cheaply according to design requirements. Then, the thermal analysis of the system was conducted for the case of natural heat convection under different electrical powers and ambient temperatures by a commercial finite element analysis (FEA) program: SolidWorks Simulation. As a result of the thermal analysis, the ultimate heat sink sizes were obtained to minimize junction temperature of LED. Finally, the experimental studies were carried out to verify the feasibility of numerical solutions that they were in good agreement.

Experimental Study and Development of Design Formula for Estimating the Ultimate Strength of Curved Plates

The curved plate has been extensively used as a structural member in many industrial fields, especially the shipbuilding industry. The present study investigated the ultimate strength and collapse behavior of the simply supported curved plate under a longitudinal compressive load. To do this, experimental apparatuses for evaluating the buckling collapse test of the curved plates was developed. Then, a series of buckling collapse experiments was carried out by considering the flank angle, slenderness ratio, and aspect ratio of plates. To examine the fundamental buckling and collapse behavior of the curved plate, elastoplastic large deflection analysis was performed using the commercial finite element analysis program. On the basis of both the experimental and FE analysis, the effects of the flank angle, slenderness ratio, and aspect ratio on the characteristics of the buckling and collapse behavior of the curved plates are discussed. Finally, the empirical design formula for predicting the ultimate strength of curved plates was derived. The proposed empirical formula is a good indicator for estimating the behavior of the curved plate.

Development of a lattice model for predicting nonlinear torsional behavior of RC beams

Seismic design criteria based on performance of structures have recently been adopted by practicing engineers in response to destructive earthquakes. A simple but efficient structural-analysis tool capable of predicting both strength and ductility is needed to analyze reinforced concrete (RC) structures subjected to such events. Hence, a three-dimensional lattice model is developed in this study to analyze torsions in high-strength RC beams. Optimization techniques for determining optimal variables in each lattice model are introduced. Pure torsion tests of RC beams were performed to use to propose a threedimensional lattice model. The experimental test results of pure torsion on RC beam specimens were used to compare with numerical results obtained using the proposed model. Then, the proposed model was also compared to 3D solid model in commercial finite element analysis program, ABAQUS. Correlation studies between the numerical and experimental results confirm that the proposed model is well capable of representing salient features of the experimental results. Furthermore, the proposed model provides better predicted displacement corresponding to peak load. than the result from ABAQUS.

Finite‐element modeling of the seismic response of reinforced masonry wall structures

AbstractModern design codes and performance‐based earthquake engineering rely heavily on computational tools to assess the seismic performance and collapse potential of structural systems. This paper presents a detailed finite‐element (FE) modeling scheme for the simulation of the seismic response of reinforced masonry (RM) wall structures. Smeared‐crack shell elements are combined with cohesive discrete‐crack interface elements to capture crushing and tensile fracture of masonry. Beam elements incorporating geometric as well as material nonlinearity are used to capture the yielding, buckling, and fracture of the reinforcing bars. The beam elements are connected to the shell elements through interface elements that simulate the bond‐slip and dowel‐action effects. An element removal scheme is introduced to enhance the robustness and accuracy of the numerical computation. The material models and interface elements have been implemented in a commercial FE analysis program. The modeling scheme is validated with data from quasi‐static cyclic tests on RM walls as well as with results from shake‐table tests on RM building systems.

Normal Mode Analysis for Connected Plate Structure Using Efficient Mode Polynomials with Component Mode Synthesis

In the engine room and stern adjacent to the main excitation force of the ship, there are many fuel and fresh water tank structures required for ship operation which are always exposed to vibrations. Therefore, it is necessary to review the anti-vibration design to prevent such vibration problems at the design stage, and for this reason, although commercial finite element analysis (FEA) programs are widely used, approximate analysis methods are still developed and used because of the limited time until modeling and analysis results are obtained. Until now, only known elastic boundary conditions have been used in many studies using approximate analysis methods used to calculate natural vibrations for beams or plates. However, many local structures, such as tank edges and equipment foundations, consist of connected structures and it is very difficult to find suitable elastic boundary conditions. Vibration analysis of many local structures in ships, such as tanks and supports for equipment, can be simplified by breaking them up into smaller subsystems which are related through geometrical conditions and natural conditions at junctions. In this study, polynomials for simple support and fixed support were proposed to represent each subsystem and a polynomial to be applied to the plate constituting the tank was proposed by combining them. Until now, there have been many studies on single beams or single plates for approximate analysis. However, there was no research on this to the extent that no reference material could be found for the connected structure. The proposed method has been applied to tanks which are bounded by bulkhead and a deck. The results of this study shows good agreements with those obtained by the FEA Software (Patran/Nastran).

Determination of the Properties of the Rubber Mounted Under the Agricultural Tractor Rollover Protective Structure Cabin Using a Hyperelastic Tensile Test and Finite Element Analysis

This study was carried out to determine the properties of materials used in the rubber mounted under the agricultural tractor rollover protective structure cabin. The natural rubber specimens were subjected to a hyperelastic uniaxial, biaxial, and planar tensile test, and a volumetric compression test for each of the four shore hardness types. The validity of the properties was assessed using ABAQUS, a commercial finite element analysis program. As a result of measuring the stress-strain curve with five repetitions of loading-unloading within each strain range, it was observed in all test results that the stress gradually eased from the initial level as the number of load iterations and strain intervals increased. The nominal tensile stress was shown in the order of uniaxial, planar, and biaxial tensile test. The nonlinear material models were similar to the tensile test results, and the Ogden 3rd model showed the best performance.

주행특성을 이용한 온 마운트 장비 추적 차량의 진동 프로파일 개발

Military products require more product life considerations than civilian products. Equipment mounted on the operating means is continuously exposed to vibrations. Therefore, vibration is an important environmental factor to consider during product development. However, it is common to proceed with product development by applying the vibration profile obtained from the U.S. military standards because securing actual vibration data related to the product is difficult in terms of cost and time. Moreover, the vibration profile of the tracked vehicle is currently unavailable. In this paper, we propose a methodology that considers the characteristics of military products and transport vibrations for generating the vibration profile of a tracked vehicle. We measured the vibration level of the tracked vehicle during transportation. In addition, by building a finite element model of the product, a vibration profile was created using ANSYS Mechanical, which is a commercial finite element analysis program. In this study, the vibration profile of the tracked vehicle was created, and it is expected to be used for future studies and help in the development of products.

Investigation of Density- and Strain Rate-dependent Strain Hardening-softening-coupled material Behavior of Polyurethane Foams using Elasto-viscoplastic Constitutive Model

Polyurethane foam (PUF) is one of the most well-known cellular materials and is widely employed in various industrial and biomedical fields thanks to its many advantages. These include mechanical and material characteristics such as low density and thermal conductivity, and high specific elastic modulus and strength. Despite of these advantages, the PUF has extremely complex material nonlinearity, with changes in density and strain rate, which is a major obstacle to material design and the application of PUF-based structures. PUF has elasto-viscoplastic behavior including three stages of material features, linear elasticity, softening/plateau with stress drop and densification. These phenomena depend strongly on strain rate and density. Therefore, in this study, a phenomenological constitutive model, namely, an elasto-viscoplastic model, was proposed to describe the density- and strain rate-dependent material nonlinear behavior of PUF. The yield surface-independent plastic multiplier, and the hardening- and softening-associated internal state variables proposed by Frank and Brockman, and Zairi et al. were adopted in the constitutive model, respectively. The proposed constitutive model was discretized using the implicit time integration algorithm and was implemented into a user-defined subroutine of the commercial finite element analysis program, ABAQUS. At the same time, a deterministic identification method for material parameters of the constitutive model was introduced to predict the precise material response of PUF under arbitrary densities and strain rates. To do this, the three-dimensional constitutive model was contracted to a one-dimensional equation, and the explicit equation for each material parameter was derived. Then, the strain hardening- and softeningdependent material parameters were calculated using experimental results, such as the work hardening ratestress curve and the yield stress-strain rate curve. After analyzing the obtained material parameters, it was found that the material parameters were strongly dependent on the density and the strain rate. Consequently, the macroscopic material response of PUF, such as a uniaxial compressive stress-strain curve, can be predicted based on the proposed method in this study.

Failure analysis of laminated composites subjected to flexural loadings

The failure of laminated composites under out-of-plane loadings is experimentally and numerically investigated. For flexure failure prediction, a modified failure criterion is proposed. A progressive failure algorithm is developed for numerical analyses. In experiments, quasi–isotropic and cross-ply laminated composites are fabricated by using unidirectional carbon fiber and glass fabric prepregs. Three-point bending test is performed and the accuracy of the failure algorithm is verified with experimental results. In addition, the flexure failure behaviors are compared with those of a commercial finite element analysis program using the other failure criteria such as maximum strain, maximum stress, and Tasi–Wu.

Idealized tension stiffening model for finite element analysis of glass fibre reinforced polymer (GFRP) reinforced concrete members

The capacity of concrete in carrying tension between two cracks is defined as tension stiffening. This paper presents the development and validation of tension stiffening model for finite element analysis (FEA) of glass fiber reinforced polymer (GFRP) reinforced concrete beams. The model was derived from an existing model for steel reinforced members using the same strain energy density. The proposed model was employed in a commercial finite element analysis program. The FEA results were compared with the test results in terms of load-deflection behavior, crack patterns, ultimate loads. It was observed that the proposed tension stiffening model was capable of predicting load deflection of shear critical GFRP reinforced concrete beams with reasonable degree of accuracy.

Effect of Anisotropic Plasticity on the Prediction of Formability of E-Form Magnesium Alloy Sheet

In this paper, the formability of E-FORM magnesium alloy sheet (as one of recent alloys for automotive magnesium sheets) is analyzed based on the comparison between the results of actual magnesium (Mg) roof forming and those of finite element (FE) simulations. The FE model considers anisotropic mechanical properties and forming limit diagram (FLD) of the investigated magnesium alloy sheet. Through the coupled experimental and numerical procedure, the dominating factors for improving the accuracy of the numerical simulations are further studied. A commercial finite element analysis program, AUTOFORM®, is used for the simulations, in which identified mechanical properties and forming limit criteria are implemented as functions of temperature and strain rate. The improvement in the prediction of formability during the warm forming of the E-FORM magnesium alloy sheet can be obtained by considering a modified hardening law at large strain region, sheet anisotropy, and the properly measured forming limit curve.

Probabilistic analysis of vertical concrete dry casks subjected to tip-over and aging effects

Vertical concrete dry casks, which provide an interim solution for the storage of spent nuclear fuel, are vulnerable to tip-over due to lateral loads. This paper explores the probabilistic structural response of a representative dry cask subjected to tip-over impact loads and aging effects. Considering concrete and soil material properties, thickness of the pad, angular velocity at the onset of tip-over, and age of the cask as variables, 200 configurations of the tip-over problem are generated by Latin Hypercube Sampling. To consider aging and the associated temporal variations, material properties of the steel parts vary in the generated configurations due to temperature variations. The generated tip-over scenarios are analyzed by numerical models developed and validated in a commercial finite element analysis program. Machine learning algorithms such as polynomial response surface models, multivariate adaptive regression splines, regression trees, support vector machines, Gaussian processes and neural networks are trained on datasets provided by the finite element analysis to develop metamodels for the maximum strain of the canister and maximum acceleration of the concrete overpack. These metamodels offer statistical approximating functions that enable efficient impact fragility analysis and evaluation of the sensitivity of the fragility to age, concrete material properties of the cask and pad, and pad thickness. The effect of aging due to alkali-silica reaction on the strain fragility is also studied, and recommendations regarding the design of vertical concrete dry casks are provided. Risk analysis is performed to estimate the dry storage cask’s risk of failure (i.e., probability of limit state exceedance) and to uncover the effect of age and design parameters on the probability of strain and acceleration exceeding predefined limits. The risk analysis shows that the probability of canister failure in the tip-over event is negligible. That is, despite expected cracks in the concrete overpack, the structural integrity of the dry cask system subjected to the tip-over impact loads is retained.

Design of Axial Flux Type Permanent Magnet Coupling with Halbach Magnet Array for Optimal Performance Considering Eddy Current Loss Reduction Using 3-D Finite Element Method

Background/Objectives: This study proposes and verifies a design method that considers the permanent magnet (PM) loss reduction of axial flux permanent magnet coupling (PMC), to replace mechanical coupling.Methods/Statistical analysis: In this study, the design of an axial magnetic flux PMC is performed using a three–dimensional (3D) commercial finite element (FEM) analysis program, and an optimum design is performed through parametric analysis. In addition, we designed a PMC that minimizes loss by analyzing the PM eddy current loss when using divided magnets.Findings: We found that some parameters (thickness of the PM, number of poles, ratio of inner radius to outer radius) act on the magnetic torque of the axial flux coupling. Using these results, we could obtain the design point. Further, to reduce the PM eddy current loss in the designed coupling, we used the PMs divided radially and circumferentially to obtain the magnet shape to minimize the loss. In addition, the fabricated coupling proved that the design results of the 3D FEM matched with the experimental results.Improvements/Applications: We propose an optimal design method of an axial flux PMC using 3D FEM, and a method to reduce eddy current loss using divided magnets

Development of PRIME for irradiation performance analysis of U-Mo/Al dispersion fuel

A prediction code for the thermo-mechanical performance of research reactor fuel (PRIME) has been developed with the implementation of developed models to analyze the irradiation behavior of U-Mo dispersion fuel. The code is capable of predicting the two-dimensional thermal and mechanical performance of U-Mo dispersion fuel during irradiation. A finite element method was employed to solve the governing equations for thermal and mechanical equilibria. Temperature- and burnup-dependent material properties of the fuel meat constituents and cladding were used. The numerical solution schemes in PRIME were verified by benchmarking solutions obtained using a commercial finite element analysis program (ABAQUS).The code was validated using irradiation data from RERTR, HAMP-1, and E-FUTURE tests. The measured irradiation data used in the validation were IL thickness, volume fractions of fuel meat constituents for the thermal analysis, and profiles of the plate thickness changes and fuel meat swelling for the mechanical analysis. The prediction results were in good agreement with the measurement data for both thermal and mechanical analyses, confirming the validity of the code.

Shear lag effects on wide U-section pre-stressed concrete light rail bridges

Recently, U-section decks have been more and more used in metro and light rail bridges as an innovative concept in bridge deck design and a successful alternative to conventional box girders because of their potential advantages. U-section may be viewed as a single vent box girder eliminating the top slab connecting the webs, with the moving vehicles travelling on the lower deck. U-section bridges thus solve many problems like limited vertical clearance underneath the bridge lowest point, besides providing built-in noise barriers. Beam theory in mechanics assumes that plane section remains plane after bending, but it was found that shearing forces produce shear deformations and the plane section does not remain plane. This phenomenon leads to distortion of the cross section. For a box or a U section, this distortion makes the central part of the slab lagging behind those parts closer to the webs and this is known as shear lag effect. A sample real-world double-track U-section metro bridge is modelled in this paper using a commercial finite element analysis program and is analysed under various loading conditions and for different geometric variations. The three-dimensional finite element analysis is used to demonstrate variations in the transverse bending moments in the deck as well as variations in the longitudinal normal stresses induced in the cross section along the U-girder\'s span thus capturing warping and shear lag effects which are then compared to the stresses calculated using conventional beam theory. This comparison is performed not only to locate the distortion, warping and shear lag effects typically induced in U-section bridges but also to assess the main parameters influencing them the most.