Dynamic fracture analysis of nonhomogeneous micropolar materials

This study proposes an innovative dynamic interaction integral (I-integral) method to conveniently decouple the dynamic stress intensity factors (SIFs) and couple stress intensity factors (CSIFs) for micropolar materials with nonhomogeneous and discontinuous properties. The main novelties of our method are as follows: (i) The I-integral does not involve the derivatives of micropolar material parameters; (ii) The I-integral is domain-independence for nonhomogeneous micropolar materials with complex material interfaces. With these advantages, the established domain-independent interaction integral (DII-integral) shows a great potential for addressing the dynamic fracture problems of nonhomogeneous micropolar materials with complex interfaces. In combination with the extended finite element method (XFEM), the DII-integral is used to study the dynamic fracture of a micropolar plate under impact loading. Good accuracy and the domain-independence of the I-integral for nonhomogeneous micropolar materials with complex material interfaces have been numerically demonstrated. Numerical simulations show that the coupling number can reduce the mode-I dynamic SIFs and weaken the stress concentration. As the coupling number N increases, there is a corresponding augmentation in the value of the mode-VI dynamic CSIFs. The increase in particle size causes the stiff particles to share more stress and couple stress, resulting in a decrease in the dynamic SIFs and CSIFs of a crack in the matrix.