Liangchi Zhang

TL;DR: In this paper, the effect of temperature and stress on plastic deformation in scratching monocrystalline silicon was investigated by means of the transmission electron microscopy, and it was shown that the size of the amorphous transformation zone and the depth of slip penetration in sample subsurface were mainly dependent on the stress field applied.

Abstract: The present study aims to investigate the residual stresses and surface hardening in ground components caused by the coupled effect of thermo-plasticity and phase transformation. A feasible numerical method was developed to accommodate appropriately the phase transformation in a workpiece experiencing critical temperature variation during grinding. The change of material properties was modelled as a function of temperature history. It found that if material properties are temperature-independent, the residual stresses in both the grinding direction and that perpendicular to it are tensile. The maximum residual stress in this case does not vary with the further increment of grinding heat. When material properties are temperature-dependent, however, the rise of grinding temperature promotes surface hardening and increases the maximum residual stress. The study showed that the volume growth associated with phase change plays an important role in the formation and nature transition of residual stresses. Nevertheless, residual stresses in the no-martensite zone is nearly unaffected by surface hardening and volume change. This paper offers insight into the understanding of surface hardening mechanism introduced by grinding.

TL;DR: In this paper, the authors used a constitutive model developed recently by the authors to analyse the multi-phase transformations in mono-crystalline silicon when subjected to nano-indentation and found that phase transformation events during indentation are closely related to the variation of both the deviatoric and hydrostatic stress components.

TL;DR: In this paper, the authors established a new model for estimating the peak indentation force of the edge chipping of rocks when using a conical or a pyramidal point-attack pick.

TL;DR: In this article, a method for calculating the viscous fictitious damping of the dynamic relaxation (DR) method was developed to overcome one of the most crucial difficulties in its application -the low convergence rate.