Crack growth modelling in single crystals based on higher order continua

This work presents several regularized crack growth models in brittle single crystals based on a combination of the micromorphic approach and continuum damage mechanics. First, a variant of micromorphic continuum, the microstrain theory, is chosen to explore the regularization capabilities of enhanced continua sparing three degrees of freedom compared to the full micromorphic approach. The difficulties in reaching final fracture of a sample are pointed out and an alternative damage criterion is proposed as a remedy which leads to a different localization pattern. Secondly, the microdamage formulation which enhances the numerical efficiency and also eliminates the final fracture difficulty is presented in detail. For all presented models, analytical solutions for governing differential equations are provided for 1D and the corresponding finite element simulation results are discussed.