Mixed mode I/II fracture criterion for orthotropic materials based on damage zone properties

In the present paper, by definition of a damage parameter, a new mixed mode I/II fracture criterion is presented for predicting the initiation and propagation of cracks in orthotropic materials. Damage parameter can be obtained with respect to micromechanics consideration that inferred from the residual tensile and shear strength of fracture process zone at crack tip vicinity. Numerical and experimental approaches are employed for estimation of material properties in damage zone. A new approach named in this research as "Representative Circular Elements (RCEs)" is proposed for simulation of variety in directions and dimensions of damage zone micro-cracks. Comparison with experimental results is demonstrated the capability of the presented criterion. (C) 2015 Elsevier Ltd. All rights reserved.