Finite Element Analysis Program Research Articles

Effect of applied force cosimulation schemes on recoupled vehicle/track problems

The aim of this paper is to discuss the effect of cosimulation on a railway vehicle/track/soil model. Firstly, only the vehicle and a flexible track are considered without taking the soil flexibility into account. Two well-known co-simulation approaches are used: a parallel approach, called Jacobi, and a sequential approach, called Gaus–Seidel. The definition of the subsystems, thus the place at which the entire system is split, is discussed. For the vehicle/track case, the split can be performed either between the wheel and the rail or between the rail and the sleepers. Moreover, it is shown that the output of each subsystem, either a kinematic quantity or a force, has a significant impact on the results since. It is indeed observed that, for the vehicle/track model, exchanging only kinematic quantities between the subsystem is less accurate but more stable than exchanging forces and kinematic quantities. The macrotimestep influence is also investigated and it is demonstrated that when the macrotimestep decreases, all co-simulation configuration converge to the same solution. Secondly, the soil flexibility and the vehicle influences are considered with a vehicle/track/soil model involving two different software environments: a multibody dedicated program for the vehicle and the track and a finite element analysis program for the soil. Generally, a deterioration of the results is observed in soft soil cases.

텔레스코픽 붐형 지게차의 붐 최적 설계

In this paper, the boom structure of a telescopic boom-type forklift truck was analyzed using ANSYS, a finite element analysis program. As a result, 494.22 MPa exceeded 456.08 MPa, allowable stress of the material, in the second boom. Thus, structural analysis was performed by reinforcing the thickness of the boom and stress was reduced. The experiment was conducted by selecting four factors of the thickness of the boom T1, T2, T3, and T4. Through response surface analysis, the curvature of the factors for stress was confirmed, and T1 was the most influential factor. Through regression equations from the variance analysis of each response, response maximization was performed to optimize mass and stress. As a result, 467.65 MPa was predicted. This exceeded allowable stress of 456.08 MPa. To obtain the result that does not exceed allowable stress, the mass was fixed at 118 kg, the initial value, and multiple response optimization was performed to limit target value and minimize stress. As a result, 432.96 MPa was expected to occur, and structural analysis resulted in 428.87 MPa stress demonstrating 13.22% reduction of stress compared to the existing model, and it is safe because allowable stress was less than 456.08 MPa.

Stability analysis of twin circular tunnels using shear strength reduction method

This paper investigates the face stability of twin circular tunnels horizontally aligned in cohesive undrained soil under plane strain conditions. The shear strength reduction method in the two-dimensional finite-element limit analysis programme is used to obtain rigorous upper and lower bounds of the factor of safety (FoS) for various depth ratios (C/D) and centre-to-centre spacing ratios (S/D) between the tunnels. Since the undrained shear strength is not a function of the mean normal stress, stability results are independent of loading directions. Therefore, the stability (in collapse or blowout) for this problem is well expressed by using Broms and Bennermarks’ original stability number N = (σs + γH − σt)/Su. The variations of the FoS have been presented for different combinations of stability numbers (N) and geometries (C/D and S/D). The FoS and the stability number results are compared and validated by using the finite-difference method as well as other existing solutions available in the literature. The results from this study are summarised in stability charts for use by designers and practising engineers.

Mechanical analysis of ribbed floor using continuum model

An approximate method based on a continuum model is proposed for analysis of floor system. A continuum model equivalent to the original ribbed floor is derived and the theoretical analytical solution of the deflection and force of the floor system is calculated. The calculation of rectangular slab whose size is 8m and 6m is carried out in the paper. Finite element analysis program SAP2000 is used for structural calculation to verify the correctness of the sample. The continuum method can result in considerable simplicity in computation analysis and provide a basis for subsequent optimization design.

Code development for the computational analysis of crack propagation in structures

In this study, the main objective was the creation of a code, which gives the capability to a Finite Element Analysis Program with no built-in crack study tools, to study the propagation of a crack, in a cracked surface. For this purpose, the Finite Element Program FEMAP 11.3.2 with solver the NX NASTRAN has been used, and the proposed code was created, using the Application Program Interface (API) of the program. The Linear Elastic Fracture Mechanics (LEFM) theory has been applied to the code, and can predict, if the crack will propagate, the trajectory of the crack, as well as the number of cycle loads required for the propagation of the crack, for given boundary conditions and loads. Finally, the Stress Intensity Factors (SIF) produced by the program, were compared with results from analytical method. Also, experimental results have been used, for the verification of the results of the trajectory of the propagation, and the cycle loads.

The ideal insertion angle after immediate loading in Jeil, Storm, and Thunder miniscrews: A 3D-FEM study

The miniscrew is effectively used to provide additional anchorage for orthodontic purposes. The aim of this study was to identify an optimal insertion angle for Jeil, Storm, and Thunder miniscrews on stress distribution at the bone miniscrew interface. To perform 3-dimensional finite element model analysis, a 3-dimensional model with a bone block was constructed with type D2 of bone quality, and with miniscrews of Storm, Thunder, Jeil, with the diameter of 2, 1.5. 1.6mm and length 15.9, 12.4, 14.4mm respectively. The miniscrews were inserted at 15° 30°, 45°, 60°, 75° and 90° to the bone surface. A simulated horizontal orthodontic force of 200 gram was applied to the centre of the miniscrews head in all models, and stress distribution and its magnitude were evaluated with a 3-dimensional finite element analysis program. In the cancellous bone, minimum stress was found at placement angles of 90° for Jeil and Storm, which was 0.37 and 0.39MPa respectively, and 15° for Thunder, which was 0.85MPa. The maximum von Mises stresses in the cancellous bone for Jeil was at 60°, which was 0.92MPa, and for Thunder at 90°, which was 1.3MPa. Each miniscrew has an ideal insertion angle, optimal insertion positions were found within 90° for Jeil and for Storm but 15° for Thunder. Clinical significance 3-dimensional finite element analysis confirmed that each miniscrew has an ideal insertion angle according to its characteristics.

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.

Revisiting the Basis for Hip Fracture Prediction Through Bone Mineral Density Scans: Large Potential Errors and Improved Methods

Abstract Researchers have attempted to evaluate the likelihood of hip fracture as a function of an engineering concept called the moment of inertia, as applied to the cross-sectional area of hip bones. While the premise is sound, the results have been disappointing. Although several authors have acknowledged that errors may arise in the current methods investigators employ to determine the cross section moment of inertia (CSMI), none have looked critically at the sources, or even the magnitude, of those errors. This paper evaluates the nature of the error that can be introduced by the use of one-dimensional bone mineral density scans to estimate the CSMI and quantifies its impact on predictive calculations. In addition, this paper presents an improved method for approximating the mechanical section properties of highly complex cross sections. The factors affecting the accuracy of the proposed method are tested, and its error rate is also quantified. The method employs a two-dimensional analysis of digital images of the subject cross section and does not require extensive user expertise or investment in expensive finite element analysis programs to implement. The limited file space necessary to install the required code means that standard smart phones could be used to directly evaluate the most complex cross section in the field.

Optimization of Cold-Formed Steel Channel Columns

Sixteen cold-formed steel channel columns with different combinations of edge and web stiffeners under axial compression forces up to failure were numerically investigated using finite element (FE) analysis program, ANSYS. The behavior characteristics; the ultimate load, stiffness, ductility and energy absorption have been selected and separately analyzed in relation to column parameters. To determine the single-performance optimization of each characteristic, Taguchi method was applied. The multi-performance optimization was also investigated using Taguchi method coupled with grey relational analysis to achieve the favorable column characteristics and to investigate the multiple-performance characteristics index of each column. The results indicated that for multi-response and a single response, the predicted results are confirmed and the errors in the predicted values using the Taguchi method with respect to the numerical values using ANSYS are acceptable and also they indicated that broken straight line web stiffener factor (WS3) was the highest contributing parameters for variation of the ultimate load of CFS columns.

Finite Element Analysis of Changes in Tensile Strain by Airsoft Gun Impact on Eye and Deformation Rate in Eyes of Various Axial Lengths.

PurposeWe have carried out three-dimensional finite element analysis (FEA) to determine the physical and mechanical response in several ocular injuries. We applied this FEA model to evaluate an airsoft gun impact on an eye and the deformation rate of eyes of various axial lengths at various velocities.MethodsThis study was carried out on a human eye model using an FEA program created by Nihon, ESI Group. The airsoft gun pellet was set to impact the eye at initial velocities of 45, 60 and 75 m/s with the addition of variation in axial length of 20 mm (hyperopia), 22 mm (emmetropia), 24 mm (myopia) and 26 mm (high myopia). Deformation of the eye was calculated as the decrease rate of the volume of the eyeball and the decrease rate of the axial length.ResultsIn all emmetropic cases, the cornea reached its strain threshold during the impact, and scleral strain showed a patchy strength distribution in the simulation. The deformation was most evident in the anterior segment, while deformation of the posterior segment was less. The decrease rate of the volume of the eyeball and decrease rate of the axial length were highest in the hyperopic eye, followed by the emmetropic eye and myopic eye, and the high myopic eye showed the lowest decrease rates among the four axial lengths in all impact velocity simulations.ConclusionThese results suggest that hyperopic eyes are most susceptible to deformation by an airsoft gun impact compared with other axial length eye models in this simulation. The considerable deformation by an airsoft gun impact shown in this study might indicate the necessity of ocular protection to avoid permanent eye injury. FEA using a human eyeball model might be a useful method to analyze and predict the mechanical features of ocular injury by an airsoft gun.

BASİT BİNDİRMELİ YAPIŞTIRMA BAĞLANTILARINDA BİNDİRME BÖLGESİ UÇ AÇI DEĞİŞİMİNİN BAĞLANTI MUKAVEMETİNE ETKİSİNİN SAYISAL OLARAK İNCELENMESİ

In adhesive bonded joints, it is recommended to design the bonding region, which is the critical zone, so that the shear stress acts. In general, the peel stresses in the adhesive joints are primarily effective in causing failure. In simple overlap joints with tensile load applied, peel stresses occur in the overlap ends by the effect of rotation. When designing simple overlap joints, it is important to design so as to minimize the effect of peel stress. In this study, in order to investigate the effect of designing the overlapping ends of the bonded materials at different angles on the joint strength, simple overlap connection models with six different tip angles (90° , 75° , 60° , 45° , 30° and 15°) were created in Ansys finite element analysis program and nonlinear stress and failure analysis was performed under the applied tensile load of the joints. As a result of the analysis, it was seen that the bond strength increased in angled models compared to the reference model (90° end angle model). According to the reference model, a strength increase of 29.1% was detected in the 15° end angle model.

Research on muzzle response characteristics of automatic gun on launching based on rigid-flexible coupling dynamics

In order to study the important influence for firing dispersion of muzzle response of automatic gun on launching, the rigid-flexible coupling dynamics model of automatic gun was established based on the rigid-flexible coupling system dynamics theory in software RecurDyn. And the flexible body of gun barrel assembly was set up by the modal synthesis method of dynamic sub-structure. The Hertz contact theory and flexible Bushing forces model were made equivalent to these constrained joints. According to the characteristic of automatic gun structure and continuous launching load, the dynamic vibrating response of simulation and analysis was made for the automatic gun on launching. The muzzle vibration response displacements in vertical and horizontal direction were obtained in the 300 rate of fire. Then the muzzle vibration velocity and acceleration with different structure clearance were also calculated by the finite element analysis program of the rigid-flexible coupling dynamics model of automatic gun. Through the comparison and analysis, the numerical solutions are closely matched with the experimental results. The results show that the vertical angle error of firing dispersion is less than 3.8% and the horizontal angle error is less than 10.2%. Thus, the simulation and experimental results verify the correctness and feasibility of this model. Further the structure design and optimization of automatic gun can be provided a reference foundation.

Structural Stress Determination at a Hot-Spot

Abstract Stress analysis by a finite element analysis program sometimes causes singularities in hot-spots. In a failure assessment, the structural stress, and membrane and bending stress should be determined in a highly stressed spot (hot-spot). When the structural stress at a hot-spot is disturbed by singularities, the stress result not only diverges, by reducing the element size, but also shows a decreased value compared to nominal stress because the stress is substituted into the von Mises equivalent stress equation. In the three-dimensional (3D) finite element model, it is hard to avoid the singularity problem at hot-spots particularly when it is subjected to loads in three axial directions. For the alternative, this study converts the 3D model into two-dimensional (2D) plane models to remove the singularity and to obtain reasonable structural stress values excluding the peak stress. The structural stress-estimating approaches applied in the 2D model were examined for whether they could avoid the structural stress reduction near the hot-spot with mesh insensitivity. The implemented approaches are stress linearization, single point away method, stress equilibrium, stress extrapolation, and the nodal force method. The results computed by each approach are compared and reconstructed to 3D stress by the Cauchy stress matrix. This study found that the difference in structural stress in 2D was eliminated after the 3D stress reconstruction.

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.

Modeling the Flexural Performance of Reinforced Concrete Built-up Beams

Finite element modeling is used for tracking the flexural response of built-up reinforced concrete beams under the influence of dominant flexural loading. ABAQUS finite element analysis program was used toward this goal, due to its superior capability to represent the mechanical properties of concrete including compressive and tensile strength in strain hardening and softening behaviors; and the features related to steel reinforcement rebar. This study is based on the comparison between the theoretical analysis by the finite element method and the experimental results. The experimental program consists of casting and testing six rectangular cross-sections of simply supported reinforced concrete beams. Two beams are cast as a reference which fully Conventional Concrete (CC) and Reactive Powder Concrete (RPC), the rest four were built-up beams made by the combination of two types of concrete in one element. The study deals with, the load which caused a first crack, ultimate carrying capacity, load and deflection behavior at mid-span of beams, cracks patterns, and damage index of the examined beams. Good agreement was gained with the available experimental results that show the effectiveness of the finite element method for simulating the flexural performance of beams.

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.

Effects of embedded trench installations using expanded polystyrene geofoam applied to buried corrugated steel arch structures

Over the years, considerable progress have been made for the improvement of the design criteria of buried culverts that increased in size and numbers with the development of information and technology in this field. This research investigates the effects of trench installation methods with expanded polystyrene (EPS) geofoam on the behavior of buried corrugated steel arch structure. A finite element analysis program, ABAQUS, was used to model and analyze the structure. For this study, an S275 corrugated steel with profiles of 152 × 51mm and 400 × 150mm, and thickness ranging from 3 mm to 7 mm was used. The structure was analyzed for three different configurations, namely; initial (without EPS geofoam), imperfect trench installation (ITI), and embedded trench installation (ETI) through three parametric analysis considering the influence of EPS geofoam’s geometry, thickness and corrugation profile of steel. The results from the finite element analyses revealed that ETI models reduced the earth pressure, deflection, and stress at the crown by 68%, 40%, and 39% on the average. It is recommended to conduct further study regarding ETI to validate the results and to further improved the design criteria of buried corrugated steel arch as it is expected to bring about cost reduction and stability for buried structures.

Comparative Evaluation of Stress Distribution of Zirconia, Cobalt Chromium and Polyetheretherketone (PEEK) Framework Material on an Atrophic Maxilla in All-on-6 Implant Treatment Concepts – A 3 Dimensional Finite Element Analysis

Aims: To evaluate the effect of prosthetic framework material on the stress distribution patterns of All-on-Six implant support system under vertical and oblique loading. Methods and Material: The CBCT images of the maxilla were converted to stereo lithography file. HYPERMESH software system was accustomed to convert 3D pictures into numerical models. Geometric model of short implant and zirconia, cobalt chromium and polyetheretherketone (PEEK) framework material were created using SOLID EDGE software and were then be inserted in the bone model. A total of six models were constructed with three different types of framework materials with four implants in the anterior maxilla region and two distal short implants and mini-abutments. The prosthetic frameworks were made with 14 teeth (central incisors to second molar bilaterally). The models were transferred through the solid works simulation program for finite element analysis and stress distribution investigation. An oblique load of 150N with 300 inclination in the linguo-buccal direction and vertical loads parallel to long axis of the tooth with 100 N magnitude were applied unilaterally on the posterior teeth of each framework. Results: Principal and Von misses stress in PEEK framework were least when compared to stresses in zirconia and cobalt chromium framework on vertical loading and oblique loading. Conclusions: PEEK as a framework material had least stress for the All on Six implant treatment concepts on vertical and oblique forces than zirconia and cobalt chromium framework.

Assessment of the stress-strain state in the weld zone for the forklift truck frame

In the context of an ever-increasing complication of both the construction of building machines and mechanisms and the conditions of their operation, the issues of achieving reliability and durability of the main welded joints are actualized, since the quality of the welded joint determines the operability of the assembly and the machine as a whole. In this regard, ensuring satisfactory weldability and obtaining a better welded joint are necessary conditions of increased strength for welded structures on which the working bodies of construction machinery, as well as mechanisms and their assembly units are mounted. The article addresses the key issues of improving the reliability of welded structures of building machines. Special attention is paid to the problems of strengthening hazardous areas, as well as the restoration of such zones in the welded structures of construction machinery. As an example, the article considers the frame of a forklift truck equipped with a hydraulic manipulator. Particular emphasis is placed on the fact that when calculating the distances between welds, it is necessary to take into account its dependence on the welding conditions and the parameters of the frame structures of construction machines. The stress-strain state of the frame was evaluated by modeling the state of the structure in various situations. Using finite element analysis programs, it was found that it is possible to reduce local stresses that exceed the tensile strength of the material and cause the risk of microcracks due to the welding of overlays with short seams in a checkerboard pattern, as well as finding the optimal parameters of the welds taking into account the stress concentration. It was also established during the study that the greatest influence on the value by stress concentration factors is exerted by the radius of the transition from the base metal to the weld metal. An increase in the transition radius from 0.1 mm to 1.0 mm makes it possible to reduce the value of the stress concentration coefficient.

Flexure Behavior of a Two Layer Reinforced Concrete Beam

This paper presents an overview of the research on flexural behavior of a two layer high strength reinforced concrete beam compared with a single layer high strength reinforced concrete beam. The experimental program consisted in testing the reaction to a flexural load of a reinforced concrete beam with two different concrete classes and a reinforced concrete beam made of the highest concrete class was made to compare the flexural behavior of the two layer beam with the single layer beam. Design and properties of the two beams in study was considered according to a preliminary economic parametric study. The two beams in study were modeled also in a finite element analysis program using experimental data.