Crack–inclusion interaction due to mismatched thermal expansion under plane stress condition

As the temperature changes in composites molding, mico-cracks are observed due to the mismatch expansion for the reinforcement and medium. An approximate expression for the change of the stress intensity factor near a Mode I crack is proposed with the consideration of the reinforcement as an inclusion that is subjected to the coupled mechanical and thermal loads under the plane stress condition. The transformation toughening theory and Eshelby inclusion method is applied in the analysis, and the mismatched thermal expansion strain is employed as the additional eigen strain. The finite element analysis is then carried out to validate the developed formula. The effect of the temperature-dependence of material properties on the crack behavior is estimated and discussed. It is found that the mismatched expansion coefficient plays an important role on the crack–inclusion interaction under the free boundary condition.