Three dimensional delamination analysis in composite open hole tensile specimens with cohesive zone method

In this article, finite element analyses (FEA) are conducted for delamination analysis in composites using three dimensional (3D) solid cohesive elements. The analyses are validated with tests. The main objective of the study is to predict damage initiation and propagation utilizing three dimensional (3D) solid cohesive elements in an implicit finite element analysis framework. First study is conducted for Double Cantilever Beam (DCB) and End Notch Flexure (ENF) specimens in ABAQUS with cohesive zone method (CZM) to model the delamination initiation and propagation. The composite material that is studied is twill and its fracture toughness data is obtained from Mode I (opening mode) and Mode II (shear mode) tests. For verification purposes, results of the delamination analyses are also compared with the experimental results available in the literature. The composite layups and cohesive zone are generated with 8 node solid elements. Second study is conducted for open hole tensile specimens in ABAQUS with CZM. First, tensile tests are performed for open hole tensile specimens without the teflon film that is used for delamination initiation. Region of delamination initiation and direction of delamination propagation for open hole specimens with the film is predicted by analyses and tests. Secondly, tensile tests are of open hole tensile specimens with the film are performed. Delamination front is scanned by the C-Scan. Maximum increment of defect area is %31.57 in experimental results and %30.6 in finite element analysis for open hole tensile specimens with the film (DOHT). Also, test and analysis results for strain gauges are compatible with each other for open hole tensile specimens without the film (OHT) and DOHT. Therefore, analysis outcomes are confirmed with experimental results