On fracture of kinked interface cracks – The role of T-stress

• Modified MTS criterion is developed to predict the fracture of bi-material cracks.
• Effect of T-stress on fracture toughness of bi-material cracks is studied.
• The significant effect of T-stress is shown on the estimation of fracture toughness.
• The proposed criterion is validated and discussed using the existing test results.
• Suggested criterion provides more accurate predictions than conventional MTS.

This paper presents a modified maximum tangential stress criterion (MMTS) for prediction of the fracture initiation conditions in kinked bi-material cracks. The criterion takes into account the effect of T-stress as well as the stress intensity factors (KI and KII) to predict the mixed mode fracture toughness of interface cracked specimens. First the fracture criterion is developed and the effect of sign and magnitude of T-stress on mixed mode fracture toughness is studied analytically. Then, the suggested criterion is evaluated using the experimental data reported for some epoxy/Aluminum Brazil-nut-sandwich specimens in the literature. The MMTS criterion is also compared with the conventional maximum tangential stress (MTS) criterion and hence, significantly improved estimates were achieved for mixed mode fracture toughness of the tested specimens.