Explicit Dynamic Finite Element Model Research Articles

Predicting the weld zones size in FSSW of 304L stainless steel plates by mathematical model based on RSM

The 300 series austenitic stainless steels are widely used in industries due to their special properties. High heat in fusion welding reduces the properties of these steels and causes many problems. Therefore, stir friction spot welding, which is a type of solid state welding, is useful and widely used in high-tech industries. In this paper, a 3D dynamic explicit finite element model is developed to simulate the friction stir spot welding of 304L stainless steel plates. Using this model, the temperature distribution and the size of weld zones (thickness of weld zones) are obtained. Then, by experimental study, the results of the temperature and the size of weld zones were obtained to be a criterion for comparing and validating the numerical results. Microstructure and hardness of these zones are determined experimentally. Finally, a mathematical model based on the response surface methodology is proposed to predict the size of weld zones. Good agreement between the numerical results that are produced by the finite element simulation, the proposed model and the experimental data is observed. The results show the maximum temperature level appears in the stir zone and it reduces by moving from the weld center. Also, by increasing the rotational speed, plunging depth and dwell time of the tool, the size of both the stir zone and the heat affected zone increase to a peak value and then the size of the latter zone decreases.

Experimental and numerical investigation of cold-formed steel telescopic studs under compression

This paper presents a thorough experimental and numerical investigation into the structural behaviour of a novel cold-formed steel (CFS) telescopic stud system under axial compression. A total of 40 specimens were tested, considering variations in screw configurations, steel grades, and section thicknesses. The test results revealed that tilting and bearing led to failure in all screw connections. In comparison to the single-screw connection with a gap at the middle of the web, the telescopic studs with 2 screws in the web, 2 screws in the flanges, and 4 screws in both the web and flanges showed approximately 35–37% higher strengths. A nonlinear explicit dynamic finite element model was then developed and validated against the test results in terms of its connection strengths and failure modes. The experimental results were compared with the design strengths determined by the current design standards (AISI S100 (2016), AS/NZS 4600 (2018), Eurocode 3 (2006), BS5950–5 (1998) and GB50018 (2002).). The comparison results revealed that the AISI S100 (2016) and AS/NZS 4600 (2018) are conservative, underestimating the connection strengths of telescopic studs with different screw layouts by 1–13%.

Deployment analysis of composite thin-walled lenticular tubes with effect of storage time and temperature

Composite Thin-walled Lenticular Tube (CTLT) is increasingly utilized in small satellites missions as a lightweight, foldable, and rollable structural material that facilitates the construction of large deployable systems. The CTLT is initially flattened and coiled around a central hub for storage before launch, during which elastic energy is stored as deformation energy, allowing it to be self-deployed on demand for use in orbit. This work presents a comprehensive investigation into the coiling, storage and deployment behaviors of CTLT that wraps around a central hub. A nonlinear explicit dynamic finite element model was developed with both deformable CTLT and rigid-bodies mechanisms including the central hub and guide rollers, as well as the complex interactions among them. The coiling mechanics characteristics such as stored strain energy and rotational moment were presented and validated against experimental data in the literature. Then, the dynamic deployment behaviors were analyzed in terms of two different deployment methods, namely, controlled deployment and free deployment. The effect of material property change during storage was also discussed through numerical experiments.

Development and application of numerical simulation and experiment for studying the compressive forming technology of transmission lines

In this paper, an explicit dynamic finite element model is built to study the compressive forming technology used in the metal connector of transmission lines of power system. Additionally, to improve the calculation accuracy, an optimized reversed calculation method for determining the equivalent friction coefficients is designed and coupled into the dynamic finite element model. It is validated with a carefully designed experiment that the coupled dynamic finite element model is effective in describing the plastic flow and in determining the grip strength of the compressive forming structure. Finally, with the dynamic finite element model, an optimized compressive forming process window is obtained for controlling the formation of edge flaws while keeping sufficient grip strength.

Design and bulletproof performance investigation on the ceramic/metal laminated composite

In the current study, seven types of laminated composites are designed to replace the existing 616 steel plate with 5 mm thickness for the bulletproof. An explicit dynamic finite element model is developed to simulate the bullet penetration process using ANSYS Workbench software. And a specific bulletproof coefficient, which considers the ultimate bulletproof speed and area density of the target plate, is proposed and calculated, and the overall bulletproof performances of the composites and 616 steel plate are compared. The specific bulletproof coefficients of seven composites are increased by 12.53%, 14.77%, 13.28%, 12.20%, 19.59%, 23.81%, and 20.67%, respectively. The type F is the optimal type among all the structures. Eventually, the optimal composites are validated under different bullet hit positions and double-bullet situations. Results show that all the seven composites and 616 steel with 5 mm thickness can effectively defend 5.62 mm bullets, and no damage or failure is observed. Although the impact stiffness and ultimate bulletproof speed are both decreased, the area density and density are also significantly decreased.

Prediction of riveting deformation for thin-walled structures using local-global finite element approach

Riveting is a crucial manufacturing process and widely used in the assembly of aeronautical thin-walled structures, such as wing panels and fuselage panels. However, the dimensional errors of final products often violate the allowed tolerance due to riveting-induced deformation, which significantly degrades the dynamic performance of aircraft and decreases the productivity. In this study, a two-step computational approach, which combines a full 3D dynamic explicit finite element model (FEM) and a local-global FEM with consideration of local bulging, is proposed to evaluate the riveting deformation for thin-walled structures. Firstly, a freedom expanding method was developed to eliminate additional stress, emerging in general connection of solid element and shell element. In addition, the plastic zone after riveting was determined by the cold expansion of hole. Secondly, the inherent deformations of nodes in typical riveted joints involved in thin-walled structure were calculated using the 3D dynamic explicit FEMs and their characteristics were also examined. Thirdly, based on the improved connection method and estimated plastic zone, the local-global FEM was built through equivalent model. Finally, three representative thin-walled riveted structures were simulated using the proposed method. By comparing predicted results and measurements, the accuracy and efficiency of the two-step computational approach are verified.

Volume-Filling Effects on Sloshing Frequency in Simplified and Explicit Dynamic Finite Element Models of Tank Wagons during Braking and Turning

Volume-Filling Effects on Sloshing Frequency in Simplified and Explicit Dynamic Finite Element Models of Tank Wagons during Braking and Turning

Collapse Failure of Prestressed Concrete Continuous Rigid-Frame Bridge under Strong Earthquake Excitation: Testing and Simulation

AbstractIn recent years, increasing attention has been paid to the collapse failures of long-span continuous rigid-frame bridges under strong earthquake excitations. This paper presents the results of a study in which a 1:15 scaled two-span prestressed concrete continuous rigid-frame bridge model with box-type piers was tested using the shake-table array test system to investigate the seismic response characteristics. Two nonlinear finite-element (FE) models were constructed. The first was a single-girder model that was used to simulate the seismic response under weak seismic waves. The second was an explicit dynamic FE model that was used to simulate the collapse and failure mechanisms of the scaled bridge under strong earthquakes. Testing revealed that the response of the central pier of the prestressed concrete continuous rigid-frame bridge was the largest under seismic excitation, and the damage first appeared at the lower end of the central pier in all cases. The numerical simulations revealed that t...

Dynamic Numerical Analysis of the “Foot – Training Shoe“Model

This paper focus on the three - dimensional dynamic research of the”foot - shoe“system. Based on the analysis on the physiology of human foot, the dynamic explicit Finite Element model of the foot and two kinds of training shoes’ sole are established by ANSA, ANSYS, DYNA and other software. Firstly the stress transfer process of falling foot is numerically simulated. Secondly the effective stresses of the foot by the new-fashioned and old-fashioned shoe are compared. Then the load characteristics of the”foot - shoe“model is studied through the acceleration, the energy, etc. Finally the research conclusion and the suggestion are summarized, which prove that the sole with the multilayer structure, anti-torsion bridge design and optimum material selection is very important for absorbing the shock and protecting the human arch, the ankle, etc., which can reduce the stress peak value of about 80%.

Seismic response study on a multi-span cable-stayed bridge scale model under multi-support excitations. Part II: numerical analysis

In recent years, local component destruction, collapse failure and the control of long-span cable-stayed bridges under strong multi-support excitations have received increasing attention. In this paper, two kinds of nonlinear finite element (FE) models are established to simulate the seismic responses and failure modes of a multi-span cable-stayed bridge scale model under multi-support excitations. One is the single girder model which is used to simulate the seismic response during four wave excitations. It can be concluded that the FE analysis results of the scale model are a good fit with those from the shaking table tests. The other one is the explicit dynamic FE model which is used to simulate the collapse and failure mechanisms of the scale model during strong earthquakes. The aggressive failure processes of the scale model under two different types of wave excitations were compared to reproduce the mechanisms in which the bearing at the middle tower failed under the El Centro (EC) wave (4.0 m/s2), and we also observed the connection failure of the cables and towers, and the elements failure of the upper beam in the middle tower, which occurred successively under a Jiangxin (JX) wave (4.0 m/s2). This simulation may be referenced as the basis for the collapse failure of a cable-stayed bridge with a large span during a strong earthquake.

A New Analysis Method of the Dry Sliding Wear Process Based on the Low Cycle Fatigue Theory and the Finite Element Method

In the present work, a combination of a dynamic explicit finite element model and the low cycle fatigue theory is used to simulate the steady-state abrasive wear occurring between an as-cast eutectoid steel and a carbide-tungsten disk. While the low cycle fatigue theory has been used to model wear in softer non-ferrous alloys, this work shows its applicability and accuracy for use in harder alloys, such as the eutectoid steel used in this research which is strengthened with added chromium. The novelty of this work lies in calculating the Manson-Coffin relation constants from a coupled finite element model with experimental tests instead of the previously used Slip line method. The D Manson-Coffin constant, obtained around 2, is in agreement with previous works given in the literature showing that the low cycle fatigue is a general wear mechanism in the steady-state wear of the alloy tested in this work.

Small Spacing Tunnels the Blasting Excavation Dynamic Effect

Kinetic research of Small spacing tunnel blasting excavation is always the hot issue both at home and abroad. In this paper, the entrance section of a small spacing tunnel is chose as an example, the Explicit dynamic finite element model and the Euler method is adopted to accurately simulate the process of blasting vibration, and the peak vibration velocity response of the tunnel is gotten. Studies has shown that, the peak velocity is more sensitive to space change when clear distance is less than 1.5 times of the hole diameter; various depth of tunnel causes different clamping action of surrounding rock, thus has different effects on peak velocity; vibration velocity at head-burst side is 5-8 times more than that at back side, vibration velocity at tunnel waist is 1.98-2.23 times more than that at up side, vibration velocity at tunnel shoulder is 1.68-1.85 times more than that at up side, so the waist position at head-burst side should be given exclusive attention.

Analysis of Sheet Curvature in Asymmetrical Cold Rolling

In asymmetric cold rolling, the workpiece is often bent downwards or upwards. A two-dimensional explicit dynamic finite element model with Arbitrary Lagrangian Eulerian (ALE) adaptive meshing technique has been employed to simulate asymmetrical sheet rolling, in which asymmetrical conditions are here due to different roll radii. To validate the simulation, the results of simulation and experiment are compared. Effects of asymmetry due to roll radii mismatch on the normal and shear distributions and on sheet curvature variations are discussed. An optimum roll radii ratio could be found to produce flat sheet. Trials were conducted to investigate the effectiveness of roll radii mismatch as an approach of sheet curvature control.

Effect of process parameters on wear in cold rotary forging by using 3D FE numerical simulation

Cold rotary forging is an advanced but very complicated metal forming technology with multifactor coupling interactive effects. The purpose of this paper is to utilise the finite element (FE) method to reveal the effect of the process parameters on the wear that occurs over the surfaces of the dies and workpiece in cold rotary forging. For this purpose, a three-dimensional (3D) elastic–plastic dynamic explicit FE model of cold rotary forging of 20CrMnTi alloy was developed using the FE software ABAQUS/Explicit, and its validity was verified experimentally. According to the valid 3D FE model, a parametric study was conducted, examining the effect of the major process parameters on the wear response and optimising the process parameters. The results of this research thoroughly reveal the complicated wear mechanisms over the dies and workpieces and provide an important guide for optimising the process parameters in cold rotary forging.

Effect of feed and roller contact start point on strain and residual stress distribution in dome forming of steel tube by spinning at an elevated temperature

Tube spinning, without mandrel, is a common process used for manufacturing pressure vessels, e.g. CNG (Compressed Natural Gas) capsules for automotive industry and fire extinguishers. The process is carried out at an elevated temperature for forming a dome on thick wall steel tube ends. Two of the most important control parameters in the process are the “roller contact start point” (RCSP) and spinning feed (pitch), both of them highly affecting the process time and deformation behavior of the tubes and therefore success and quality of the product. In this article, using a three-dimensional dynamic explicit finite element model, the effects of these parameters are investigated on circumferential, axial and radial (thickness) strains of the formed tube in three thickness layers of the tube wall. The model is also verified by experiment. While circumferential strain is shown to be independent of the feed, axial and thickness strains are highly affected by both the feed and roller contact start point. It is shown that when the roller contact start point distance from the free end of the tube increases, there is a risk of indentation instead of normal bending behavior. It is also shown that axial strain has an inverse relation with feed, i.e. decreasing the feed results in further elongation of the tube. On the other hand, thickness strain increases by increasing the feed, so bigger thicknesses are expected in domes manufactured by higher feeds. In addition, it is shown that increasing the feed results in a decrease of the equivalent strain. The amount of residual stress (regardless of the temperature change) increases with increasing feed and its distribution is more uniform for higher distances of the contact start point from the free end.

Drug delivery patterns for different stenting techniques in coronary bifurcations: a comparative computational study

The treatment of coronary bifurcation lesions represents a challenge for the interventional cardiologists due to the lower rate of procedural success and the higher risk of restenosis. The advent of drug-eluting stents (DES) has dramatically reduced restenosis and consequently the request for re-intervention. The aim of the present work is to provide further insight about the effectiveness of DES by means of a computational study that combines virtual stent implantation, fluid dynamics and drug release for different stenting protocols currently used in the treatment of a coronary artery bifurcation. An explicit dynamic finite element model is developed in order to obtain realistic configurations of the implanted devices used to perform fluid dynamics analysis by means of a previously developed finite element method coupling the blood flow and the intramural plasma filtration in rigid arteries. To efficiently model the drug release, a multiscale strategy is adopted, ranging from lumped parameter model accounting for drug release to fully 3-D models for drug transport to the artery. Differences in drug delivery to the artery are evaluated with respect to local drug dosage. This model allowed to compare alternative stenting configurations (namely the Provisional Side Branch, the Culotte and the Inverted Culotte techniques), thus suggesting guidelines in the treatment of coronary bifurcation lesions and addressing clinical issues such as the effectiveness of drug delivery to lesions in the side branch, as well as the influence of incomplete strut apposition and overlapping stents.

Advanced Gun System Gun and Projectile Dynamic Model Results and Correlation to Test Data

BAE Systems is currently developing and testing a 155 mm advanced gun system (AGS) and a long range land attack projectile (LRLAP) as a part of the DDG-1000 ship development program. For this development, it is important to understand the barrel and projectile dynamics, including the interaction of the barrel and the projectile in the bore as well as the projectile tip-off parameters at exit. An abaqus explicit dynamic finite element model has been developed to compare results with test data that were taken on June 18, 2003, at the BAE Systems site at the Alliant Techsystems Proving Ground (ATPG) during AGS propellant testing. The abaqus model includes the gun barrel, the projectile used for propellant testing (a steel slug), the M110 gun mount, and the recoil system. Features of the model incorporate settling of the barrel due to gravity, gun recoil, in-bore interaction of the projectile and the barrel using contact surfaces, and the initial flight of the projectile after bore exit. The abaqus model results have been compared with gun firing test data acquired during propellant testing at Elk River, MN. These comparisons include barrel and projectile displacements, angular velocities, and axial accelerations. The abaqus model results are also compared to similar models of the test conditions with the simulation of barrel dynamics (simbad) gun dynamics code and the ibhvg2 interior ballistics code.

Investigation on contact parameters in cold rotary forging using a 3D FE method

Cold rotary forging is an advanced but very complicated metal plastic forming technology with continuous local plastic deformation. Investigating the contact parameters between the contact interactions has a great importance to improve the contact performance. This paper is aimed to utilize the finite element (FE) method to study the contact parameters in a complex continuous local forming technology of cold rotary forging. For this purpose, a reasonable 3D elastic–plastic dynamic explicit FE model of cold rotary forging of 20CrMnTi alloy is developed using the FE software ABAQUS/Explicit. Based on this valid 3D FE model, some important contact parameters, such as the contact pressure, contact slip rate, contact slip distance, and contact force, are numerically examined in detail. The results of this research help to better understand the complicated contact mechanisms in cold rotary forging.

Effect of equivalent feed amount per revolution on cold rotary forging process by 3D elastic–plastic dynamic explicit FE method

Cold rotary forging is an advanced and very complex incremental metal forming process with multifactor coupling interactive effects. Previous research is mainly based on experimental and analytical methods and thus cannot provide full details on the deformation characteristics and mechanisms of cold rotary forging. In the current work, a decisive factor in cold rotary forging, namely equivalent feed amount per revolution , is first determined, and its mathematical expression is presented. A reasonable three-dimensional elastic–plastic dynamic explicit finite element model of cold rotary forging of a cylindrical workpiece was established under the ABAQUS software environment. Through numerous simulation calculations and the analysis of equivalent plastic strain, it has been found that there are three plastic penetrating states of the cylindrical workpiece under different . On the basis of these plastic penetrating states, the effect laws of on the metal flow, degree of inhomogeneous deformation of workpiece and force and power parameters have been investigated, and thus, the deformation characteristics and mechanisms of cold rotary forging have been thoroughly revealed. The results show that with increasing , the ‘mushroom’ effect of the deformed cylindrical workpiece becomes less obvious and the deformation becomes more homogeneous, while the maximum axial forging force and forging moment gradually increase. Second, the effect of by changing the inclination angle γ of the upper die on the cold rotary forging process is different from that by changing the feed rate v of the lower die or the rotational speed n of the upper die.

Finite element modeling of ultrasonic surface rolling process

Ultrasonic surface rolling (USRP) is a newly developed process in which ultrasonic vibration and static force are applied on work-piece surface through the USRP operator to generate a nanostructured surface layer with mechanical behaviors highly improved. Compared with other surface severe plastic deformation (S 2PD) methods, it can realize mechanized machining and be directly used for preparing final product. Notwithstanding the excellent performance of USRP, elaborate relation between process parameters and surface layer characteristics is still inadequacy due to inconvenient and costly experimental evaluation. Therefore, in this paper a three-dimensional finite element model (FEM) has been developed to predict the treatment conditions that lead to surface nanocrystallization. Simulated results of surface deformation, stress and strain are investigated to assess the formation of nanostructured layer. The numerical results from the FEM corresponds well with the values measured experimentally, indicating that this dynamic explicit FEM is a useful tool to predict the processing effects and to relate the treating parameters with the surface layer in terms of the size of nanostructured layer, residual stress and work hardening.