사용자서브루틴을 이용한 저온용 고장력강재의 파단 예측

초록

Stress triaxiailty is recognized as one of the important factors for prediction of failure strain of ductile metals. This study deals with effect of average stress triaxiality on failure strain of EH36 steel. Tensile tests are carried out for round specimens and flat specimens with different notches from relatively smooth to very sharp levels. Numerical simulations of each specimen are performed by using ABAQUS. From comparison of result between experiments and numerical analysis, failure initiation points in numerical simulations are identified. Failure strain curves for various dimensionless critical energy levels are established in the average stress triaxiality domain and compared with identified failure strain points. It is observed that most failure initiation points are approximated with 100% dimensionless critical energy curve. From these results, it is concluded that the failure strains are well expressed as a function of the average stress triaxiality and we formulate the failure strain of EH36 steel. In order to assess the validity of failure strain curve obtained by previous processes, we perform a numerical analysis of each specimen by using ABAQUS user defined subroutine VUSDFLD.