Effect of Crack-Crazing Patterns Interactions on Energy Release Rates Seddiki, H 1 and Chabaat, M 2 1 Doctorate student, 2 Professor, Built Environment Research Laboratory, Civil Engineering Faculty, University of Sciences and Technology Houari Boumediene, B.P. 32 El Alia, Bab Ezzouar, Alger 16111, Algeria mchabaat2002@yahoo.com & hseddiki2007@yahoo.fr ABSTRACT In this study, interactions between a main crack and a surrounding layer of crazing patterns are considered. Analysis of the stress field distribution as well as the energy induced during these interactions is based on the resolution of some differential equations along with appropriate boundary conditions and the use of a numerical approach. It is proven throughout this study that the crazes growth occurs along directions normal to the major principal stress directions and constitutes an important toughening mechanism. Thus, the mode I Stress Intensity Factor (SIF) is employed to quantify the effects of this damage on the main crack and the Energy Release Rate (ERR) due to the linear propagation of the main crack and also to the translational change in the growth of the damage. It is proven, herein, that crazes closer to the main crack dominate the resulting interaction effect and reflect an anti-shielding of the damage while a reduction constitutes a material toughness. KEYWORDS: Displacement, major and minor principal stress, stress intensity factor, energy release rate, crack, crazing patterns. 1. INTRODUCTION There is sufficient experimental evidence that in most cases, a propagating crack is surrounded by a damage zone which often precedes the crack itself. This zone usually consists of slip lines or shear bands in metals, microcracks in ceramics and polymers, and crazes in amorphous polymers. Thus, the existence of these defects affects progressively the propagation of cracks already present in some materials. Because this damage can constitute an important toughening mechanism, problems dealing with crack microcracks interactions have received considerable research attention since they were introduced to fracture mechanics. As a result, a wide body of literature, on this topic, exist [1-4]. Thus, analysis of the distribution of surface crazes in the vicinity of a stationary edge crack in a polystyrene (PS) sheet in tension has shown the craze growth occurs along directions parallel to the minor principal stress axis. This behaviour has been thoroughly documented and extensively discussed in a number of papers [5-7].