Finite element analysis aided fracture toughness evaluation in tear test of aluminum alloys

Abstract

A rather good correlation between fracture properties obtained from tear test fracture toughness value J_IC has already been reported in the previous study. A method of estimating fracture toughness parameters directly from the tear test is studied and presented in this study with a help of the finite element analysis. Tear test is carried out using specimen with a deep notch ratio of a/W=0.3 which is recommended from the result of finite element analysis, while its other geometry is held same as that of the standard tear test one. In such test, load-load line deflection curve and crack initiation point are recorded. Then, the fracture toughness J_IC can be successfully evaluated by putting the area under the load-deflection curve up to the crack initiation point into the Rice's simple J integral estimation formula. Crack initiation point can be experimentally detected by the DC electrical potential method or the compliance changing rate method developed by the authors. It is also shown that crack initiation point may be also detected by the maximum load if side grooves are added to the specimen. Moreover, it is verified that crack extension resistance, i.e., tearing modulus T_mat, from the tear test coincides with that obtained from the test of CT specimen.