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On the modeling of large ratcheting strains and anisotropy in pearlitic steel

Göran Johansson (Institutionen för tillämpad mekanik ; Institutionen för tillämpad mekanik, Material- och beräkningsmekanik)
Göteborg : Chalmers University of Technology, 2006. ISBN: 91-7291-814-4.- 170 pages s.
[Doktorsavhandling]

Thermodynamically consistent constitutive material models for describing the large strain response of polycrystalline metals are proposed. Emphasis is put on the multiaxial ratcheting under cyclic loading and the evolution of anisotropy in pearlitic steel. For cyclic loading, the experimentally observed large ratcheting strains is modelled by the classical Armstrong-Frederick type of evolution with several back-stresses. In addition, with the purpose to mimic a multiaxial ratcheting rate, a dependence on the Hessian of the yield function is suggested. Furthermore, the model parameters are identified against different sets of experimental data for pearlitic steel. Next, two different models for the evolution of deformation induced anisotropy at large strains are proposed. The first model is inspired by recent material modeling for applications in biomechanics. In the second model, the reorientation of the pearlitic grains under large deformations is homogenized analytically to the macroscopic length scale. The use of a Hill type of yield criterion on the macroscopic length scale is motivated from the homogenization. In order to increase computational efficiency, an adaptive time-stepping algorithm is proposed for solving boundary value problems under cyclic loading conditions with a large amount of load cycles. The algorithm is based on large time increments that span several loading cycles and is less computationally demanding as compared to standard time incrementation. Finally, the performance of the models is illustrated by numerical examples. In particular, the models are used to predict the long term deformations of a railway turnout when it is subjected to repeated loading.

Nyckelord: Large strains, Kinematic hardening, Ratcheting, Anisotropy, Plasticity



Denna post skapades 2006-09-06. Senast ändrad 2013-09-25.
CPL Pubid: 22448

 

Institutioner (Chalmers)

Institutionen för tillämpad mekanik
Institutionen för tillämpad mekanik, Material- och beräkningsmekanik

Ämnesområden

Fastkroppsmekanik

Chalmers infrastruktur

Relaterade publikationer

Inkluderade delarbeten:


Computational modeling of inelastic large ratcheting strains


Modeling of anisotropic inelasticity in pearlitic steel at large strains due to deformation induced substructure evolution


Parameter identification and modeling of large ratcheting strains in carbon steel


Examination

Datum: 2006-09-29
Tid: 13.00
Lokal: 13.00 HA2-salen, Hörsalsvägen, Chalmers
Opponent: Professor, Bob Svendssen, Institute for Mechanics, University of Dortmund, Germany

Ingår i serie

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie 2495