Mixed mode I/II fracture criterion for arbitrary cracks in orthotropic materials considering T-stress effects

Applying the new experimental midpoint concept on strain energy density for fracture assessment of composite materials

“…Extremely helpful as these criteria are, they are too conservative and are not able to be applied for industrial engineering applications. As a remarkable result of this study, some research has been done to improve the extended criteria [40,42,44,[48][49][50][51]76,77,81,82].…”

“…In the other words, based on the RIS concept, the isotropic stress state is substituted for the anisotropic stress state of the crack tip, while including several coefficients that attributed to the reinforcement effect of fibers on the matrix. Numbers of studies recently have been carried out to study the coefficients to improve the fracture criteria [43][44][45]49,[75][76][77]. As a result of the RIS concept, the theoretical relation between the mode I and II toughness and energy release rate is obtained [74].…”

“…Also, based on various fracture criteria, the theoretical relation between K Ic andK IIc ,which is called damage factor, is obtained to facilitate deriving the value of the K IIc according to theK Ic . The importance of establishing accurate theoretical relationship between K Ic andK IIc , or damage factor, is to avoid the practically arduous and equally costly experimental tests to deriveK IIc , which are approximately impossible to achieve the correct value [40,42,44,[48][49][50][51]76,77,82].…”

“…Applying the RIS concept to the conventional fracture criteria of isotropic materials (such as SED, MTS, and SER) allows the development of these criteria for orthotropic materials. The validity of the proposed fracture criteria for orthotropic materials based on RIS is evaluated with experimental test results [43][44][45][46][47].…”

“…Therefore, the crack onset and growth occur in the matrix, which is isotropic material. This phenomenon thoroughly examined and proved that criteria based on the reinforced isotropic solid (RIS) improved the prediction of crack growth at the orthotropic materials [40,42,44,45,63,[75][76][77].…”