Seminarium Instytutowego Seminarium Mechaniki im. W. Olszaka i A. Sawczuka

1. Regularizing Shear Bands Using Dynamic length scale (10:00-11:30) 2. Materiałowo konstrukcyjne problemy wysoko obciążalnych prądowo napowietrznych linii elektroenergetycznych i sieci trakcyjnych kolei dużych prędkości (11:30-13:00)

1. prof. George Z. Voyiadjis, (10:00-11:30) 2. dr hab. inż. T. Knych, prof. AGH, (11:30-13:00)

poniedziałek, 2 czerwca 2008, godz. 10:00, sala Aula (II p.)

REGULARIZING SHEAR BANDS USING DYNAMIC LENGTH SCALE Dr. George Z. Voyiadjis Department of Civil and Environmental Engineering Louisiana State University, Baton Rouge, Louisiana, USA Abstract The shear band formation in the finite element analysis using the regular continuum is mesh dependent. It usually has the size of one or two element lengths, and the convergence to a unique solution with successively finer meshes is generally not possible. To overcome this difficulty, a week nonlocal analysis is performed in this work by using gradient terms in the hardening parameters of the elastoplastic analysis in order to regularize the mesh dependency. Along with the gradient term use is made of a material length scale, which is obtained here using nano indentation experiments. Two models of variable length scales are proposed here in order to incorporate the high strain rates into account. The first model is a simple power low model that depends on dynamic hardness. The second model is physically based one where the Nye factor is assumed to be a function of temperature and strain rate. This approach is applied to cold rolled 1018 steel in this work with explicit time integration finite element scheme. The results show good regularization of the shear band initiation as well as the shear band width.