Delamination of beams under transverse shear and bending

Two delamination problems are studied: a straight beam of rectilinearly orthotropic material under transverse loading and a curved beam (or C-specimen) with cylindrical material anisotropy under pure bending. Results are presented for each problem for the dependence on the crack length of both the energy release rate and a measure of the relative amount of mode II to mode I. The number of nondimensional parameters in the problems is fairly large, including two dimensionless elasticity parameters. Considerable simplification of the parametric dependence in the straight beam problem is achieved using an orthotropic rescaling technique due to Suo. Asymptotic solutions based on elastic beam theory are also presented. A by-product of the present analysis is the finding that frictionless contact of the crack faces near one of the crack tips has little effect on the other tip, even in the case when the size of the contact zone is large relative to the length of the crack.