A Modified Shell Element Model Combined with Yld91 Yield Function in Simulating Aluminum Alloy Applied Hydroforming

2015 ◽  
Vol 639 ◽  
pp. 435-442 ◽  
Author(s):  
Fei Fei Zhang ◽  
Jun Chen ◽  
Jie Shi Chen ◽  
Xin Hai Zhu ◽  
Shi Jian Yuan
Keyword(s):  
Normal Stress ◽  
Fe Simulation ◽  
Applied Pressure ◽  
Shell Element ◽  
Material Model ◽  
Element Model ◽  
Yield Function ◽  
Element Formulation ◽  
Thickness Direction ◽  
Forming Process

Hydroforming has been used widely across many industrial fields. Large applied pressure during hydroforming makes it necessary to consider the influence of normal stress in the thickness direction, while in FE simulation, the use of traditional shell element based upon plane-stress assumption is not appropriate in such cases. Here, the traditional shell element is modified by changing the constitutive relation which took into account the normal stress in the thickness direction, and the modified shell element formula is combined with Yld91 yield function to simulate the forming process of Aluminium alloy. Then the element formulation and material model is implemented into the FE code Ls-Dyna by means of USER interface. Two examples are carried out and good correlations are obtained when compared to the traditional shell element and solid element.

Shell Element Formulation Based Finite Element Modeling, Analysis and Experimental Validation of Incremental Sheet Forming Process

2015 ◽  
Author(s):  
Govind N. Sahu ◽  
Sumit Saxena ◽  
Prashant K. Jain ◽  
J. J. Roy ◽  
M. K. Samal ◽  
...  
Keyword(s):  
Finite Element ◽  
Thickness Distribution ◽  
Shell Element ◽  
Time Profile ◽  
Experimental Results ◽  
Computational Time ◽  
Element Formulation ◽  
Forming Process ◽  
Element Analysis ◽  
Shell Elements

This paper presents the effect of shell element formulations on the response parameters of incremental sheet metal forming process. In this work, computational time, profile prediction and thickness distribution are investigated by both finite element analysis and experimentally. The experimental results show that the thickness distribution is in good agreement with the results obtained with Belytschko-Tsay (BT) and Improved Flanagan-Belytschko (IFB) shell element formulations. These two shell element formulations do trade-off between computational time and accuracy. For more accurate results, the BT shell element formulation is better and for less computational time with good results, the IFB shell element is preferable. Finally, BT shell element formulation has been chosen for FE Analysis of ISF process in HyperWorks, since the results of thickness distribution and profile prediction is in better agreement with the experimental results as well as the computational time is less among the shell elements.

Solid Shell Element and its Application in Roll Forming Simulation

2007 ◽  
Vol 340-341 ◽  
pp. 347-352 ◽  
Author(s):  
Da Yong Li ◽  
Ying Bing Luo ◽  
Ying Hong Peng
Keyword(s):  
Degrees Of Freedom ◽  
Shell Element ◽  
Element Model ◽  
Roll Forming ◽  
Good Prospect ◽  
Solid Shell ◽  
Forming Process ◽  
Forming Simulation ◽  
Assumed Natural Strain ◽  
Roll Forming Process

Solid shell element models which possess only translational degrees of freedom and are applicable to thin structure analyses has drawn much attention in recent years and presented good prospect in sheet metal forming. In this study, a solid shell element model is introduced into the dynamic explicit elastic-plastic finite element method. The plane stress constitutive relation is assumed to relieve the thickness locking and the selected reduced integration method is used to overcome volumetric locking. The assumed natural strain method is adopted to resolve shear locking and trapezoidal locking problem. Two benchmark examples and a stage of roll forming process are calculated, and the calculating results are compared with those by solid element model, which demonstrates the effectiveness of the element.

In-Vacuo Modal Dynamic Response of the Human Skull

1974 ◽  
Vol 96 (2) ◽  
pp. 490-494 ◽  
Author(s):  
R. E. Nickell ◽  
P. V. Marcal
Keyword(s):  
Shell Element ◽  
Element Model ◽  
General Purpose ◽  
Element Formulation ◽  
Human Skull ◽  
Natural Modes ◽  
Modes Of Vibration ◽  
Doubly Curved ◽  
Insight Into ◽  
Good Agreement

A finite element model of a human skull is analyzed in order to determine the lowest natural modes of vibration. A doubly curved, triangular, thin shell element formulation is used, within the framework of a general-purpose program, to investigate the effect of various support systems on the frequencies and modal shapes. The frequencies are found to be in good agreement with the results of other investigators and the modal shapes offer some insight into a modified theory of craniocerebral damage that includes both skull rotation and cavitation as pathogenic mechanisms.

Development of New Hybrid Shell Element Takinging the Normal Stress into Account

2013 ◽  
Vol 313-314 ◽  
pp. 202-205
Author(s):  
Hong Lu ◽  
Wen Huang
Keyword(s):  
Stress Distribution ◽  
Normal Stress ◽  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Shell Element ◽  
Mixed Formulation ◽  
Normal Strain ◽  
Thickness Direction ◽  
Stress Prediction

The calculation of the stress distribution in the forming stage of sheet metal forming is critical to the accuracy of springback simulation. In order to improve the accuracy of stress prediction, a new mixed shell element is presented. Two pseudo nodes are added in the thickness direction so that the normal strain can be calculated using the displacements of the nodes. Mixed formulation is used instead of that of pure displacement. As a result, the accuracy of stress prediction is improved. Examples are given to show the improvement.

Springback Investigation in Roll Forming of a V-Section

2014 ◽  
Vol 553 ◽  
pp. 643-648 ◽  
Author(s):  
Akbar Abvabi ◽  
Joseba Mendiguren ◽  
Bernard F. Rolfe ◽  
Matthias Weiss
Keyword(s):  
Elastic Modulus ◽  
Continuous Process ◽  
High Strength Steels ◽  
Shell Element ◽  
High Strength ◽  
Material Model ◽  
The Body ◽  
Roll Forming ◽  
Forming Process ◽  
Advanced High Strength Steels

To have fuel efficient vehicles with a lightweight structure, the use of High Strength Steels (HSS) and Advanced High Strength Steels (AHSS) in the body of automobiles is increasing. Roll forming is used widely to form AHSS materials. Roll forming is a continuous process in which a flat strip is shaped to the desired profile by passing through numerous sets of rolls. Formability and springback are two major concerns in the roll forming of AHSS materials. Previous studies have shown that the elastic modulus (Young’s modulus) of AHSS materials can change when the material undergoes plastic deformation and the main goal of this study is to numerically investigate the effect of a change in elastic modulus during forming on springback in roll forming. Experimental loading-unloading tests have been performed to obtain the material properties of TRIP 700 steel and incorporate those in the material model used in the numerical simulation of the roll forming process. The finite element simulations were carried out using MSC-Marc and two different element types, a shell element and a solid-shell element, were investigated. The results show that the elastic modulus diminution due to plastic strain increases the springback angle by about 60% in the simple V-section roll forming analyzed in this study.

Temperature Gradient Mechanism on Laser Bending of Borosilicate Glass Sheet

2010 ◽  
Vol 132 (1) ◽  
Author(s):  
Dongjiang Wu ◽  
Guangyi Ma ◽  
Fangyong Niu ◽  
Dongming Guo
Keyword(s):  
Temperature Gradient ◽  
Borosilicate Glass ◽  
Fe Simulation ◽  
Glass Sheet ◽  
Laser Forming ◽  
Thickness Direction ◽  
Forming Process ◽  
Primary Defect ◽  
Laser Bending ◽  
Forming Mechanism

The present work is a research on the laser forming process of borosilicate glass sheet. The laser forming mechanism was analyzed, and the temperature gradient mechanism was considered as the main forming mechanism of glass bending. According to the experimental results, a thermomechanical finite element (FE)-simulation was applied for investigating the temperature distribution and thermal stress in the thickness direction of the specimen. Cracks, as the primary defect, were summarized to three kinds: “Y” cracks, straight cracks, and arc cracks, while their forming mechanisms were proposed.

Mixed-dimensional coupling modeling for laser forming process

2014 ◽  
Vol 228 (16) ◽  
pp. 2950-2959
Author(s):  
Hong Shen ◽  
Jun Hu ◽  
Zhenqiang Yao
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Shell Element ◽  
Element Model ◽  
Thermomechanical Analysis ◽  
Coupling Method ◽  
Computational Time ◽  
Laser Forming ◽  
Forming Process ◽  
Shell Elements

Efficient laser forming modeling for industrial application is still in the developing stage and many researchers are in the process of modifying it. Conventional three-dimensional finite element models are still expensive on computational time. In this paper, a finite element model adopting a shell-solid coupling technique is developed for the thermomechanical analysis of laser forming process. In the shell-solid coupling method, an additional shell element plane is utilized to transfer heat flux and displacement from the solid elements to the shell elements. The effects of the additional interface shell element thickness on temperature distribution and final distortion are investigated. The presented shell-solid coupling method is evaluated by the results of three-dimensional simulations and experimental data.

scholarly journals Analysis of gusset plate of contemporary bridge truss girder

2016 ◽  
Vol 11 (3) ◽  
pp. 188-196
Author(s):  
Wojciech Siekierski
Keyword(s):  
Stress Distribution ◽  
Normal Stress ◽  
Cross Section ◽  
Equivalent Stress ◽  
Shell Element ◽  
Element Model ◽  
Beam Element ◽  
Gusset Plates ◽  
Gusset Plate ◽  
Element Modelling

Trussed structures in modern bridge building usually have “W” bracing. Structural joints are often based on application of gusset plates. Experimental tests of stress distribution in such gusset plates are rather sparse. Lab testing of scaled bridge truss girder was carried out in Poznań University of Technology in Poznań. Investigation into stress distribution in gusseted joint was carried out. Test results were put against results obtained from analyses of two finite element models: beam-element model and shell-element model. Normal stress and Huber-Mises equivalent stress distributions within gusseted joint were analysed. General conclusions are: a) normal stress distribution in gusseted joint cross-section, perpendicular to truss flange axis, is nonlinear and extreme stresses occur near cross-section edges, b) Huber-Mises equivalent stress distribution in the cross-section of gusset plate near its connection to truss flange is nonlinear and extreme stresses occur near centre of the cross-section, c) assessment of normal stresses in gusseted joints should not be carried out with an aid of beam-element modelling, d) it is possible to assess Huber-Mises equivalent stresses in gusset plate near its welded connection to rigid flange with an aid of beam-element modelling if non-uniform distribution of shear stress is taken into account, e) shell-element modelling of gusseted joint provides satisfactory accuracy of normal and equivalent stress assessment, f) beam-element modelling of friction grip bolts is sufficiently accurate for shell-element models of steel joints analysed within elastic range of behaviour.

Deviations between FE Simulation and Experiments in the SPIF Process

2011 ◽  
Vol 473 ◽  
pp. 937-946
Author(s):  
Ioannis Vasilakos ◽  
Jun Gu ◽  
Hans Vanhove ◽  
Hugo Sol ◽  
Joost R. Duflou
Keyword(s):  
Fe Simulation ◽  
Single Point ◽  
Model Identification ◽  
Material Model ◽  
Initial Guess ◽  
Inverse Methods ◽  
Material Behavior ◽  
Fe Model ◽  
Forming Process ◽  
Tool Set

Single Point Incremental Forming (SPIF) is a modern and flexible alternative to traditional forming techniques. It thanks its flexibility to the fact that it does not require a dedicated tool set to operate. Numerical simulation of the SPIF process requires an accurate FE model. In the past several attempts have been undertaken to use inverse methods for sheet metal SPIF material model identification based on shearing, tensile and indenting tests. The basic idea of this paper is that the results of inverse methods can be improved by using the SPIF process itself as experimental data source. A SPIF experiment dedicated for material identification on a simple geometry using large step sizes is presented and compared with the FE simulation of the forming process based on an initial guess for the material behavior.

Micromechanics Based Composite Material Model for Impact and Crashworthiness Explicit Finite Element Simulation

1999 ◽  
Author(s):  
Ala Tabiei
Keyword(s):  
Finite Element ◽  
Mechanical Model ◽  
Composite Structures ◽  
Laminated Composite ◽  
Shell Element ◽  
Material Model ◽  
Element Model ◽  
Micro Model ◽  
Explicit Finite Element ◽  
Laminated Composite Materials

Abstract A micro-mechanical model is developed for laminated composite materials and implemented in the explicit finite element method. The objective of this study is to get an accurate and simple micro-model, which can be used in the displacement-based explicit finite element packages. The micro-mechanical model implemented in the explicit finite element code can be used for simulating the behavior of composite structures under various loads such as impact and crash. The stress-strain relation for the micro-model is derived for shell element. As a demonstration case of the developed micro-model a finite element model of Graphite/Epoxy tube structure is developed and simulated under axial crash.

Sign in / Sign up

Export Citation Format

Share Document