Fatigue pre-cracking life estimation for fracture toughness test specimens

Alipour Ghasabi, Amir
This study is done for predicting fatigue crack initiation life and propagation life of a crack initiated at a notch and grown to a desired length. Both numerical analysis and experimental study was done for single edge notch bend type specimen. Crack initiation life prediction was done using strain-life approach applying different available models. For this purpose 2-D and 3-D finite element model of the specimen was created in Abaqus. By simulating the 2-D and 3-D model under static loading, notch maximum stress was found to calculate the notch elastic stress concentration factor. Applying Neuber’s rule local stresses and strains of notched part was calculated. These values were then compered to values found by elasto-plastic analysis done for 3-D model in Abaqus. Then, fatigue crack initiation life was predicted. For the propagation part, the required number of cycles to grow the initiated crack from 1 mm length to a desired length was calculated by using Walker and Paris equations. At the end the predicted lives were compared to experimental ones. It is found that reasonable agreement could be obtained, and the established procedure could be used in planning the preparation stages of cracked beam specimens.
Citation Formats
A. Alipour Ghasabi, “Fatigue pre-cracking life estimation for fracture toughness test specimens,” M.S. - Master of Science, Middle East Technical University, 2018.