Bs. Henry et Ar. Luxmoore, 3-DIMENSIONAL EVALUATION OF THE T-STRESS IN-CENTER CRACKED PLATES, International journal of fracture, 70(1), 1995, pp. 35-50
Thick three-dimensional (3-D) finite element models of centre cracked
plates are used to study the variation in the biaxiality factor beta w
ith the crack aspect ratio a/w. The use of two widely accepted methods
to evaluate the T-stress in two-dimensions, namely the boundary layer
method and the displacement field method, to calculate the T-stress i
n three-dimensions is studied. It is shown that the boundary layer met
hod gives results that compare rather well with the two-dimensional pl
ane strain values (maximum difference of 6 percent), while the displac
ement field method results are about 15 percent lower. Two parameters
are shown to affect the three-dimensional evaluation of the biaxiality
factor, namely the material's Poisson's ratio nu and the specimen's t
hickness t. The biaxiality factor is directly proportional to nu and i
nversely proportional to t. Three-dimensional analysis is required to
assess correctly the effect of nu and t on beta.