Article,
Calibration and evaluation of seven fracture models
International Journal of Mechanical Sciences, 47 (4-5): 719 - 743 (2005)A Special Issue in Honour of Professor Stephen R. Reid's 60th Birthday.
DOI: DOI: 10.1016/j.ijmecsci.2005.03.003
Abstract
Over the past 5 years, there has been increasing interest of the automotive,
aerospace, aluminum, and steel industries in numerical simulation
of the fracture process of typical structural materials. Accordingly,
there is a pressure on the developers of leading commercial codes,
such as ABAQUS, LS-DYNA, and PAM-CRASH to implement reliable fracture
criteria into those codes. Even though there are several options
to address fracture in these and other commercial codes, no guidelines
are given for the users as to which fracture criterion is suitable
for a particular application and how to calibrate a given material
for fracture. The objective of the present paper is to address the
above issues and present a thorough comparative study of seven fracture
criteria that are included in libraries of material models of non-linear
finite element codes. A set of 15 tests recently conducted by the
authors on 2024-T351 aluminum alloy is taken as a reference for the
present study. The plane stress prevails in all these tests. These
experiments are compared with the constant equivalent strain criterion,
the Xue-Wierzbicki (X-W) fracture criterion, the Wilkins (W), the
Johnson-Cook (J-C) and the CrachFEM fracture models. Additionally,
the maximum shear (MS) stress model, and the fracture forming limit
diagram (FFLD) are included in the present evaluation. All criteria
are formulated in the general 3-D case for the power law hardening
materials and then are specified for the plane stress condition.
The advantage of working with plane stress is that there is one-to-one
mapping from the stress to the strain space. Therefore, the fracture
criteria formulated in the stress space can be compared with those
expressed in the strain space and vice versa. Fracture loci for all
seven cases were constructed in the space of the equivalent fracture
strain and the stress triaxiality. Interesting observations were
made regarding the range of applicability and expected errors of
some of the most common fracture criteria. Besides evaluating the
applicability of several fracture criteria, a detailed calibration
procedure for each criterion is presented in the present paper. It
was found rather unexpectedly that the MS stress fracture model closely
follows the trend of all tests except the round bar tensile tests.
The X-W criterion and the CrachFEM models predict correctly fracture
in all types of experiments. The W criterion is working well in certain
ranges of the stress triaxiality.
