Approach for Determining Fracture Mechanical Properties from Tests on Small Size Specimens at Room Temperature

An approach based on finite-element (FE) simulations of the crack propagation process is used to determine fracture mechanical properties on sub-size specimens. The objective is to establish small size testing technology for the determination of fracture mechanical properties. The applicability of the evaluation procedure is verified on the ferritic-martensitic steel T91. In this approach the fracture process is described by using a cohesive zone model (CZM). The CZM model needs two parameters to be identified on sub-size specimens.The geometry of sub-size three point bending specimen is 27x3x4 mm3 with side grooves. To identify both parameters another experimental test on notched sub-size tensile specimens is required. After parameter identification on sub-size specimens simulation of a standard-size specimen is performed using the same cohesive zone parameters to predict the J-R curve of the standard-size specimen.