Nonlinear Kinematic Hardening Identification for Anisotropic Sheet Metals With Bending-Unbending Tests

2000 ◽  
Vol 123 (4) ◽  
pp. 378-383 ◽  
Author(s):  
M. Brunet ◽  
F. Morestin ◽  
S. Godereaux
Keyword(s):  
Kinematic Hardening ◽  
Bending Moment ◽  
Complex Loading ◽  
Tensile Tests ◽  
Sheet Metals ◽  
Element Analysis ◽  
Inverse Approach ◽  
Initial Anisotropy ◽  
Identification Technique ◽  
Constitutive Parameters

An inverse identification technique is proposed based on bending-unbending experiments on anisotropic sheet-metal strips. The initial anisotropy theory of plasticity is extended to include the concept of combined isotropic and nonlinear kinematic hardening. This theory is adopted to characterize the anisotropic hardening due to loading-unloading which occurs in sheet-metals forming processes. To this end, a specific bending-unbending apparatus has been built to provide experimental moment-curvature curves. The constant bending moment applied over the length of the specimen allows one to determine numerically the strain-stress behavior but without Finite Element Analysis. Four constitutive parameters have been identified by an inverse approach performed simultaneously on the bending and tensile tests. Our identification results show that bending-unbending tests are suitable to model quite accurately the constitutive behavior of sheet metals under complex loading paths.

Non-Linear Kinematic Hardening Identification for Anisotropic Sheet-Metals With Bending-Unbending Tests

2000 ◽  
Author(s):  
M. Brunet ◽  
F. Morestin ◽  
S. Godereaux
Keyword(s):  
Kinematic Hardening ◽  
Bending Moment ◽  
Complex Loading ◽  
Sheet Metals ◽  
Element Analysis ◽  
Initial Anisotropy ◽  
Non Linear ◽  
Identification Technique ◽  
Stress Behaviour ◽  
Constitutive Parameters

Abstract An inverse identification technique is proposed based on bending-unbending experiments on anisotropic sheet-metal strips. The initial anisotropy theory of plasticity is extended to include the concept of combined isotropic and non-linear kinematic hardening. This theory is adopted to characterise the anisotropic hardening due to loading-unloading which occurs in sheet-metals forming processes. To this end, a specific bending-unbending apparatus has been built to provide experimental moment-curvature curves. The constant bending moment applied over the length of the specimen allows to determined numerically the strain-stress behaviour but without Finite Element Analysis Four constitutive parameters have to be identified by an inverse approach. Our identification results show that bending-unbending tests are suitable to model quite accurately the constitutive behaviour of sheet metals under complex loading paths.

Springback Analysis of Aluminum Alloy Sheet Metals by Yoshida-Uemori Model

2016 ◽  
Vol 725 ◽  
pp. 566-571 ◽  
Author(s):  
Takeshi Uemori ◽  
Kento Fujii ◽  
Toshiya Nakata ◽  
Shinobu Narita ◽  
Naoya Tada ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Sheet Metal ◽  
Kinematic Hardening ◽  
Yield Function ◽  
Alloy Sheet ◽  
Aluminum Alloy Sheet ◽  
Sheet Metals ◽  
Initial Anisotropy ◽  
Hardening Rules ◽  
Prediction Capability

During the last few decades, the enhancement of prediction capability of the sheet metal forming have been increasing dramatically. High accurate yield criteria and wokhardening model (especially, non-linear kinematic hardening model) have a great importance for the prediction of the final shapes of sheet metal. However, the predicted springback accuracy of aluminum alloy sheet metal is not still good due to their complicated plastic deformation behaviors.In the present research, the springback deformation of aluminum alloy sheet metals were investigated by finite element calculation with consideration of initial anisotropy and the Bauschinger effect. In order to examine the effect of the initial and deformation induced anisotropy on the springback deformation, several types of high accurate yield function and hardening rules are utilized in the present research. The calculated springback by Yoshida 6th yield function [1] and Yoshida-Uemori model [2] shows an excellent agreement with the corresponding experimental data, while the other models underestimate the springback.

Comparison Between Two Experimental Procedures for Cyclic Plastic Characterization of High Strength Steel Sheets

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
G. B. Broggiato ◽  
F. Campana ◽  
L. Cortese ◽  
E. Mancini
Keyword(s):  
Sheet Metal ◽  
High Strength Steel ◽  
Kinematic Hardening ◽  
High Strength Steels ◽  
High Strength ◽  
Bending Test ◽  
Compression Tests ◽  
Element Analysis ◽  
Constitutive Parameters ◽  
Springback Prediction

In finite element analysis of sheet metal forming the use of combined isotropic-kinematic hardening models is advisable to improve stamping simulation and springback prediction. This choice becomes compulsory to model recent materials such as high strength steels. Cyclic tests are strictly required to evaluate the parameters of these constitutive models. However, for sheet metal specimens, in case of simple axial tension-compression tests, buckling occurrence during compression represents a serious drawback. This is the reason why alternative set-ups have been devised. In this paper, two experimental arrangements (a cyclic laterally constrained tension-compression test and a three-point fully reversed bending test) are compared so as to point out the advantages and the disadvantages of their application in tuning the well-known Chaboche’s hardening model. In particular, for tension-compression tests, a new clamping device was specifically designed to inhibit compressive instability. Four high strength steel grades were tested: two dual phases (DP), one transformation induced plasticity (TRIP) and one high strength low alloy material (HSLA). Then, the Chaboche’s model was calibrated through inverse identification methods or by means of analytical expressions when possible. The proposed testing procedure proved to be successful in all investigated materials. The achieved constitutive parameters, obtained independently from the two experimental techniques, were found to be consistent. Their accuracy was also been assessed by applying the parameter set obtained from one test to simulate the other one, and vice versa. Clues on what method provides the better transferability are given.

scholarly journals Failure of Laminated Composites at Thickness Discontinuities Under Complex Loading and Elevated Temperatures

2000 ◽  
Author(s):  
S. Lee ◽  
W. G. Knauss
Keyword(s):  
Elevated Temperatures ◽  
Laminated Composites ◽  
Failure Process ◽  
Bending Moment ◽  
Complex Loading ◽  
Matrix Cracking ◽  
Interface Failure ◽  
Element Analysis ◽  
Initiation Point ◽  
Failure Initiation

Abstract Failure initiation of laminated composites with discontinuous thickness has been studied in terms of typical structural load description (tension, shear force and bending moment) rather than in terms of micromechanics considerations. Four types of specimens of different stacking sequence were examined to determine failure initiation, analyzed subsequently via a finite element analysis (ABAQUS), divided into two groups that evoke cross-ply failure, on the one hand, and delamination type failure on the other. For unidirectional fiber orientation in the tension direction and across the interface, failure occurs through cracking and delamination. While the initiation strength for this failure mode is significantly higher than for cross-ply configurations, the residual strength after initiation increases only marginally (10%) beyond the initiation point. For cases involving cross-plies on either side of the interface, failure initiation occurs by matrix cracking. In these cases the residual load bearing capability was 20 to 30% higher than the corresponding failure initiation loads. The data are analyzed in terms of the Tsai-Hill criterion and in terms of an energy release criterion that has been discretized in a manner consistent with a non-singular treatment of the step “discontinuity”. Assuming that time dependent aspects of the failure process are not dominant, elevated temperatures did not change the general results of how bending and tension loads interact; however the magnitude at which the failures occur depends on the temperature, with increasing temperature leading to decreasing load tolerance.

Character Analysis of Balance and Imbalance of Varying Rigidity of Rigid Pile Composite Foundation under Seismic Load

2014 ◽  
Vol 1065-1069 ◽  
pp. 19-22
Author(s):  
Zhen Feng Wang ◽  
Ke Sheng Ma
Keyword(s):  
Finite Element ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Element Model ◽  
Composite Foundation ◽  
Seismic Load ◽  
Seismic Loads ◽  
Element Analysis ◽  
Rigid Pile ◽  
Rigid Pile Composite Foundation

Based on ABAQUS finite element analysis software simulation, the finite element model for dynamic analysis of rigid pile composite foundation and superstructure interaction system is established, which selects the two kinds of models, by simulating the soil dynamic constitutive model, selecting appropriate artificial boundary.The influence of rigid pile composite foundation on balance and imbalance of varying rigidity is analyzed under seismic loads. The result shows that the maximum bending moment and the horizontal displacement of the long pile is much greater than that of the short pile under seismic loads, the long pile of bending moment is larger in the position of stiffness change. By constrast, under the same economic condition, the aseismic performance of of rigid pile composite foundation on balance of varying rigidity is better than that of rigid pile composite foundation on imbalance of varying rigidity.

scholarly journals A Material Model for the Orthotropic and Viscous Behavior of Separators in Lithium-Ion Batteries under High Mechanical Loads

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4585
Author(s):  
Marian Bulla ◽  
Stefan Kolling ◽  
Elham Sahraei
Keyword(s):  
Mechanical Behavior ◽  
Lithium Ion ◽  
Material Model ◽  
Tensile Tests ◽  
Element Analysis ◽  
Rate Dependent ◽  
Novel Material ◽  
Li Ion ◽  
Role Based ◽  
Drive Systems

The present study is focused on the development of a material model where the orthotropic-visco-elastic and orthotropic-visco-plastic mechanical behavior of a polymeric material is considered. The increasing need to reduce the climate-damaging exhaust gases in the automotive industry leads to an increasing usage of electric powered drive systems using Lithium-ion (Li-ion) batteries. For the safety and crashworthiness investigations, a deeper understanding of the mechanical behavior under high and dynamic loads is needed. In order to prevent internal short circuits and thermal runaways within a Li-ion battery, the separator plays a crucial role. Based on results of material tests, a novel material model for finite element analysis (FEA) is developed using the explicit solver Altair Radioss. Based on this model, the visco-elastic-orthotropic, as well as the visco-plastic-orthotropic, behavior until failure can be modeled. Finally, a FE simulation model of the separator material is performed, using the results of different tensile tests conducted at three different velocities, 0.1 mm·s−1, 1.0 mm·s−1 and 10.0 mm·s−1 and different orientations of the specimen. The purpose is to predict the anisotropic, rate-dependent stiffness behavior of separator materials in order to improve FE simulations of the mechanical behavior of batteries and therefore reduce the development time of electrically powered vehicles and consumer goods. The present novel material model in combination with a well-suited failure criterion, which considers the different states of stress and anisotropic-visco-dependent failure limits, can be applied for crashworthiness FE analysis. The model succeeded in predicting anisotropic, visco-elastic orthotropic and visco-plastic orthotropic stiffness behavior up to failure.

Preliminary Parametric Assessment of a Bolted Endplate Joint under Combined Axial Force and Cyclic Bending Moment

2011 ◽  
Vol 255-260 ◽  
pp. 718-721
Author(s):  
Z.Y. Wang ◽  
Q.Y. Wang
Keyword(s):  
Finite Element Analysis ◽  
Axial Force ◽  
Seismic Design ◽  
Axial Load ◽  
Failure Modes ◽  
Bending Moment ◽  
Element Analysis ◽  
Cyclic Behaviour ◽  
Joint Behaviour ◽  
Steel Joints

Problems regarding the combined axial force and bending moment for the behaviour of semi-rigid steel joints under service loading have been recognized in recent studies. As an extended research on the cyclic behaviour of a bolted endplate joint, this study is performed relating to the contribution of column axial force on the cyclic behaviour of the joint. Using finite element analysis, the deteriorations of the joint performance have been evaluated. The preliminary parametric study of the joint is conducted with the consideration of flexibility of the column flange. The column axial force was observed to significantly influence the joint behaviour when the bending of the column flange dominates the failure modes. The reductions of moment resistance predicted by numerical analysis have been compared with codified suggestions. Comments have been made for further consideration of the influence of column axial load in seismic design of bolted endplate joints.

ANALYSIS OF AN INTERNAL FIXATION OF A LONG BONE FRACTURE

2005 ◽  
Vol 05 (01) ◽  
pp. 89-103 ◽  
Author(s):  
K. RAMAKRISHNA ◽  
I. SRIDHAR ◽  
S. SIVASHANKER ◽  
V. K. GANESH ◽  
D. N. GHISTA
Keyword(s):  
Stress Shielding ◽  
Axial Loading ◽  
Bending Moment ◽  
Fracture Site ◽  
Long Bone ◽  
Radius Of Curvature ◽  
Element Analysis ◽  
Long Bone Fracture ◽  
Fracture Interface ◽  
Tensile Surface

A major concern when a fractured bone is fastened by stiff-plates to the bone on its tensile surface is excessive stress shielding of the bone. The compressive stress shielding at the fracture-interface immediately after fracture-fixation delays bone healing. Likewise, the tensile stress shielding of the healed bone underneath the plate also does not enable it to recover its tensile strength. Initially, the effect of a uniaxial load and a bending moment on the assembly of bone and plate is investigated analytically. The calculations showed that the screws near the fracture site transfers more load than the screws away from the fracture site in axial loading and it is found that less force is required when the screw is placed near to fracture site than the screw placed away from the fracture site to make the bone and plate bend with same radius of curvature when subjected to bending moment. Finally, the viability of using a stiffness graded bone-plate as a fixator is studied using finite element analysis (FEA): the stiffness-graded plate cause less stress-shielding than stainless steel plate.

Generation of Cyclic Stress-Strain Curves for Sheet Metals

2000 ◽  
Author(s):  
K. M. Zhao ◽  
J. K. Lee
Keyword(s):  
Constitutive Model ◽  
Kinematic Hardening ◽  
Optimization Procedure ◽  
High Strength ◽  
Cyclic Stress ◽  
Bending Moments ◽  
Sheet Metals ◽  
Stress Strain ◽  
Normal Anisotropy ◽  
Material Parameters

Abstract The main objective of this paper is to generate cyclic stress-strain curves for sheet metals so that the springback can be simulated accurately. Material parameters are identified by an inverse method within a selected constitutive model that represents the hardening behavior of materials subjected to a cyclic loading. Three-point bending tests are conducted on sheet steels (mild steel and high strength steel). Punch stroke, punch load, bending strain and bending angle are measured directly during the tests. Bending moments are then computed from these measured data. Bending moments are also calculated based on a constitutive model. Normal anisotropy and nonlinear isotropic/kinematic hardening are considered. Material parameters are identified by minimizing the normalized error between two bending moments. Micro genetic algorithm is used in the optimization procedure. Stress-strain curves are generated with the material parameters found in this way, which can be used with other plastic models.

Numerical Modeling and Analytical Investigation of Autofrettage Process on the Fluid End Module of Fracture Pumps

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Mahdi Kiani ◽  
Roger Walker ◽  
Saman Babaeidarabad
Keyword(s):  
Residual Stresses ◽  
Kinematic Hardening ◽  
Analytical Formula ◽  
Strain Analysis ◽  
Material Model ◽  
Analytical Investigation ◽  
Stress Strain ◽  
Element Analysis ◽  
Hardening Material ◽  
Strain Evolution

One of the most important components in the hydraulic fracturing is a type of positive-displacement-reciprocating-pumps known as a fracture pump. The fluid end module of the pump is prone to failure due to unconventional drilling impacts of the fracking. The basis of the fluid end module can be attributed to cross bores. Stress concentration locations appear at the bores intersections and as a result of cyclic pressures failures occur. Autofrettage is one of the common technologies to enhance the fatigue resistance of the fluid end module through imposing the compressive residual stresses. However, evaluating the stress–strain evolution during the autofrettage and approximating the residual stresses are vital factors. Fluid end module geometry is complex and there is no straightforward analytical solution for prediction of the residual stresses induced by autofrettage. Finite element analysis (FEA) can be applied to simulate the autofrettage and investigate the stress–strain evolution and residual stress fields. Therefore, a nonlinear kinematic hardening material model was developed and calibrated to simulate the autofrettage process on a typical commercial triplex fluid end module. Moreover, the results were compared to a linear kinematic hardening model and a 6–12% difference between two models was observed for compressive residual hoop stress at different cross bore corners. However, implementing nonlinear FEA for solving the complicated problems is computationally expensive and time-consuming. Thus, the comparison between nonlinear FEA and a proposed analytical formula based on the notch strain analysis for a cross bore was performed and the accuracy of the analytical model was evaluated.

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