A combined isotropic-kinematic hardening model for the simulation of warm forming and subsequent loading at room temperature

2010 ◽  
Vol 26 (1) ◽  
pp. 126-140 ◽  
Author(s):  
Bekim Berisha ◽  
Pavel Hora ◽  
Arne Wahlen ◽  
Longchang Tong
Keyword(s):  
Room Temperature ◽  
Kinematic Hardening ◽  
Warm Forming ◽  
Hardening Model

Uniaxial Ratchetting of 316FR Steel at Room Temperature— Part II: Constitutive Modeling and Simulation

1998 ◽  
Vol 122 (1) ◽  
pp. 35-41 ◽  
Author(s):  
N. Ohno ◽  
M. Abdel-Karim
Keyword(s):  
Constitutive Model ◽  
Constitutive Modeling ◽  
Critical State ◽  
Room Temperature ◽  
Stress Ratio ◽  
Dynamic Recovery ◽  
Kinematic Hardening ◽  
Hysteresis Loops ◽  
Hardening Model ◽  
Stress Cycling

Uniaxial ratchetting experiments of 316FR steel at room temperature reported in Part I are simulated using a new kinematic hardening model which has two kinds of dynamic recovery terms. The model, which features the capability of simulating slight opening of stress-strain hysteresis loops robustly, is formulated by furnishing the Armstrong and Frederick model with the critical state of dynamic recovery introduced by Ohno and Wang (1993). The model is then combined with a viscoplastic equation, and the resulting constitutive model is applied successfully to simulating the experiments. It is shown that for ratchetting under stress cycling with negative stress ratio, viscoplasticity and slight opening of hysteresis loops are effective mainly in early and subsequent cycles, respectively, whereas for ratchetting under zero-to-tension only viscoplasticity is effective. [S0094-4289(00)00501-6]

Warm forming process for an AA5754 train window panel

2021 ◽  
pp. 1-32
Author(s):  
Antonio Piccininni ◽  
Andrea Lo Franco ◽  
Gianfranco Palumbo
Keyword(s):  
Material Characterization ◽  
Room Temperature ◽  
Warm Forming ◽  
Railway Vehicle ◽  
Fe Model ◽  
Forming Process ◽  
Vehicle Component ◽  
Mechanical Approach ◽  
Thermal Simulations ◽  
Critical Regions

Abstract A warm forming process is designed for AA5754 to overcome low room temperature formability. The solution includes increased working temperature and is demonstrated with a railway vehicle component. A Finite Element (FE) based methodology was adopted to design the process taking into account also the starting condition of the alloy. In fact, the component's dent resistance can be enhanced if the yield point is increased accordingly: the stamping process was thus designed considering the blank in both the H111 (annealed and slightly hardened) and H32 (strain-hardened and stabilized) conditions that were preliminarily characterized. Tensile and formability tests were carried out at different temperature and strain rate levels, thus providing the data to be implemented within the FE model (Abaqus/CAE): the stamping was at first simulated at room temperature to evaluate the blank critical regions. Subsequently, the warm forming process was designed by means of an uncoupled thermo-mechanical approach. Thermal simulations were run to properly design the heating strategy and achieve an optimal temperature distribution over the blank deformation zone (according to the results of the material characterization). Such a distribution was then imported as a boundary condition into the mechanical step (Abaqus/Explicit) to determine the optimal process parameters and obtain a sound component (strain severity was monitored implementing an FLD-based damage criterion). The simulation model was validated experimentally with stamping trials to fabricate a sound component using the optimized heating strategy and punch stroke profile.

scholarly journals Analysis of Undrained Seismic Behavior of Shallow Tunnels in Soft Clay Using Nonlinear Kinematic Hardening Model

2020 ◽  
Vol 10 (8) ◽  
pp. 2834
Author(s):  
Mohsen Saleh Asheghabadi ◽  
Xiaohui Cheng
Keyword(s):  
Finite Element ◽  
Kinematic Hardening ◽  
Soft Clay ◽  
Hysteresis Loops ◽  
Stiffness Degradation ◽  
Triaxial Tests ◽  
Embedment Depth ◽  
Ground Acceleration ◽  
Cyclic Shear ◽  
Hardening Model

In this study, a soil–tunnel model for clay under earthquake loading is analyzed, using finite element methods and a kinematic hardening model with the Von Mises failure criterion. The results are compared with those from the linear elastic–perfectly plastic Mohr–Coulomb model. The latter model does not consider the stiffness degradation caused by imposing cyclic loading and unloading to the soil, whereas the kinematic hardening model can simulate this stiffness degradation. The parameters of the kinematic hardening model are calibrated based on the results of experimental cyclic tests and finite element simulation. Here, two methods—one using data from cyclic shear tests, and the other a new method using undrained cyclic triaxial tests—are used to calibrate the parameters. The parameters investigated are the peak ground acceleration (PGA), tunnel lining thickness, tunnel shape, and tunnel embedment depth, all of which have an effect on the resistance of the shallow tunnel to the stresses and deformations caused by the surrounding clay soils. The results show that unlike traditional models, the nonlinear kinematic hardening model can predict the response reasonably well, and it is able to create the hysteresis loops and consider the soil stiffness degradation under the seismic loads.

Development of Adapted Material Testing for Cold Pilgering Process of ODS Tubes

2013 ◽  
Vol 554-557 ◽  
pp. 2243-2251 ◽  
Author(s):  
Katia Mocellin ◽  
Esteban Vanegas ◽  
Yann de Carlan ◽  
Roland E. Logé
Keyword(s):  
Room Temperature ◽  
Kinematic Hardening ◽  
Oxide Dispersion Strengthened ◽  
Stress And Strain ◽  
Oxide Dispersion ◽  
Martensitic Steels ◽  
Uniform Loading ◽  
Cold Pilgering ◽  
Irradiation Level ◽  
Numerical Approaches

Development of fast-neutron sodium-cooled Generation IV reactors is resulting in extremely severe environment conditions for cladding tubes [1]. Both temperature and irradiation level will increase compared to the nowadays conditions. Due to their characteristics in irradiated environment, the oxide dispersion strengthened (ODS) ferritic and martensitic steels are natural candidate cladding materials[2]. However, they exhibit low deformation capabilities at room temperature, leading to problematic issues for forming such as pilgering. In order to improve the fabrication route for tubes, both metallurgical and numerical approaches can be conducted [3,4,5]. To reach predictive description of damage location and evolution, an adapated Latham and Cockoft model has been developed. This model is, of course, highly depending on the stress and strain prediction of the numerical model which itself is linked to the behavior law. In this work, we will describe an adapted material test developed in order to reproduce the cyclic, non uniform loading of the material during pilgering. An advanced cyclic beahvior law is introduced in the software. The model of Chaboche using 2 isotropic and 2 kinematic variables is chosen[6]. An inverse analysis procedure is used to identify both isotropic and kinematic hardening parameters. The results obtained using the identified behavior law are compared to both experimental observation and to other models including monotonic or cyclic laws identified on traditional test.

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