We consider control problems for the variational inequality describing a single degree of freedom elasto-plastic oscillator. We are particularly interested in finding the ”critical excitation”, i.e., the lowest energy input excitation that drives the system between the prescribed initial and final states within a given time span. This is a control problem for a state evolution described by a va...

In this study, the hydrogen transport phenomenon was numerically evaluated by using hydrogen-enhanced localized plasticity (HELP) mechanisms. Two dominant governing equations, namely, the hydrogen transport model and the elasto-plastic model, were introduced. In addition, the implicitly formulated equations of the governing equations were implemented into ABAQUS UMAT user-defined subroutines. T...

The question of ‘generalization’ to finite strains of the constitutive relations of infinitesimal strain theory of elasticity, and classical elasto-plasticity with isotropic and kinematic hardening, is critically examined. Simple generalizations, which lead to physically plausible material behaviour, are presented. The current controversies surrounding (i) the choice of stress-rate in the above...

A continuum-based micromechanical model is employed for the prediction of the elasto-plastic behavior of periodic microstructural arrays that can generate negative values of Poisson's ratios. The combined effects of the negative Poisson's ratio generated by the array microstructure and the elastoplastic behavior of the constituents are studied. A design methodology for the determination of the ...

The concept of representative crack elements has been successfully introduced to phase-field fracture in previous publications, where anisotropic elasticity [1], visco-elasticity [2], elasto-plasticity and surface friction [3] are considered at small deformations. This framework allows overcome unrealistic predictions for the kinematics, reported e.g. Strobl Seelig [4], Steinke Kaliske [5], kno...

In this paper we consider the dynamics of dislocations with the same Burgers vector, contained in the same glide plane, and moving in a material with periodic obstacles. We study two cases: i) the particular case of parallel straight dislocations and ii) the general case of curved dislocations. In each case, we perform rigorously the homogenization of the dynamics and predict the corresponding ...

This thesis presents efficient finite element solutions of poro-elasto-acoustic coupled problems using modal-based approaches adapted to non conservative problems, combined with an interpolation method in frequency, based on Padé approximants. The performance of the proposed methods and their combination is demonstrated on several 1D to 3D coupled problems. Conclusions are drawn to provide indi...

The stability and elasto-mechanical properties of tetragonal and cagelike or clathrate nanowires of Si are investigated and compared using molecular dynamics simulations. Our results show that cagelike nanowires, while possessing lesser density, are able to maintain their structural integrity over a larger range of strain conditions than the tetrahedral nanowires, making them a better candidate...

We demonstrate refinements of a simple elastic-viscous-plastic rheological model with the addition thixotropic term to better flow human blood. The alteration this will contribute representation lightly structured complex materials. (EVP) framework requires thixotropy for more accuracy in fitting and predicting thixo-elasto-visco-plasticity flows microstructure. performance added features by co...