ECCM18 - 18 th European Conference on Composite Materials Athens, Greece, 24-28 th June 2018 1 S. AhmadvashAghbash, M. Engül, F. E. Öz, R. Amali, and N. Ersoy, A COMPARATIVE NUMERICAL STUDY AIMING TO REDUCE COMPUTATION COST FOR MODE-I DELAMINATION SIMULATIONS S. AhmadvashAghbash 1 , M. Engül 1 , F. E. Öz 1 , R. Amali 2 , and N. Ersoy 1,2 1 Department of Mechanical Engineering, Boğaziçi University, Bebek, 34342, Istanbul, TURKEY Emails: sina.ahmadvashaghbash@boun.edu.tr, mehmet.engul@boun.edu.tr, fatih.oz@boun.edu.tr 2 Department of Engineering, Design, and Mathematics, University of West of England, Bristol, UNITED KINGDOM Emails: ramin2.amali@uwe.ac.uk, nuri.ersoy@boun.edu.tr Keywords: Double Cantilever Beam, Cohesive Zone Model, Mode I Fracture Toughness, Interfacial Strength Abstract This study presents a procedure which aims to find a solution that allows the use of coarser mesh in modelling the Mode I delamination behaviour of AS4/8552 Carbon-Epoxy laminates. This approach is based on an artificial increase of the cohesive zone length by lowering the interfacial strength. In this paper, Double Cantilever Beam (DCB) tests are performed experimentally to obtain the load- displacement curve and to evaluate the mode I interlaminar fracture toughness value of AS4/8552. Moreover, 2D and 3D numerical models are applied to simulate DCB test with commercial Finite Element Analysis (FEA) software ABAQUS. A parametric study is carried out for both models to investigate the effect of various parameters such as mesh size, interfacial strength and interface stiffness values. Results shows that the propagation of delamination can be accurately predicted with coarser meshes by optimizing the parameters used in Cohesive Zone Modelling. 1. Introduction The urge to reduce the design costs of composite structures relying on experimental testing has encouraged researchers to develop advanced computational tools to simulate the progressive failure of fibre-reinforced composite materials. Among the different failure mechanisms that occur in laminated composites, delamination is one of the predominant ones. However, the simulation of progressive delamination contains numerical difficulties related to the proper definition of the interlaminar properties and the requirement of extremely refined mesh which leads to increase in run-time. Therefore, developing a numerical approach for delamination growth by using coarser mesh is quite substantial. Cohesive Zone Model (CZM) is one of the common approaches that is performed to simulate delamination by using decohesion elements [1-6]. Decohesion elements predict the onset of the softening process at the interface between plies by strength-based approach and fracture mechanics to predict delamination propagation. Compared to alternative methods such as Virtual Crack Closure Technique (VCCT) [7], CZM provides the ability to have several crack paths without predefined crack propagation directions. Turon et. al. [8] proposed an approach based on an artificial increase of the cohesive zone length by reducing the interfacial strength while keeping the fracture toughness constant. Meanwhile, the number of elements is kept constant in the cohesive zone, where the increase of cohesive zone length leads to