کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
825499 1470043 2009 11 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
On scale invariance in anisotropic plasticity, gradient plasticity and gradient elasticity
موضوعات مرتبط
مهندسی و علوم پایه سایر رشته های مهندسی مهندسی (عمومی)
پیش نمایش صفحه اول مقاله
On scale invariance in anisotropic plasticity, gradient plasticity and gradient elasticity
چکیده انگلیسی

A simple but robust scale invariance argument earlier used to derive flow rules for macroscopic kinematic hardening plasticity from the configuration of single slip is now applied to consider yielding of fiber reinforced composites as first pioneered, on a purely phenomenological basis, by Tony Spencer and his co-workers. It is shown that the approach results to simpler constitutive equations than those obtained by the phenomenological methodology of the standard representation theorems for isotropic functions. The argument is then extended to obtain simplified but physically-based constitutive equations for gradient plasticity and gradient elasticity as such type of approaches have been extensively adopted in the recent literature to interpret interesting phenomena at the micron scale, not captured by classical theories. For gradient plasticity, the scale invariance argument involves two steps: first the algebraic elimination of the orientation tensors defining crystal slip between the microscopic expressions for the back (dislocation) stress and plastic strain rate; and, second, a maximization procedure for the rate of plastic work (maximum dissipation or entropy production). For gradient elasticity the algebraic elimination of the lattice orientation vectors between the microscopic expressions for the lattice stress and lattice strain suffices, as no dissipation occurs in this case. As an application of gradient theory, we consider, in particular, the size effect in strain gradient-dependent plastic layers and the removal of elastic singularities at screw dislocation lines and crack tips under a shear mode loading are considered. It is shown that a number of insightful results are obtained which are in accord with experimental observations and/or elaborate numerical simulations. This is largely due to the fact that the method used provides simple expressions for the strain/stress field which turns out to be governed by a non-homogeneous Helmholtz equation for which analytical solutions are available.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Engineering Science - Volume 47, Issues 11–12, November–December 2009, Pages 1089–1099
نویسندگان
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