Micro-to-macro transitions for heterogeneous material layers accounting for in-plane stretch

The computational micro-to-macro transition framework couples heterogeneities on the microscopic scale to the macroscopic response of a continuum. The objective here is to apply this framework to macroscopic material layers capable of undergoing an in-plane stretch in addition to the normal opening mode. This is achieved using the continuum interface theory of Gurtin and Murdoch (1975) which endows the interface with its own energetic structure. The relation of the macroscopic kinematic descriptors of the interface deformation to the averaged underlying microscopic quantities is consistently derived using the Hill-type averaging theorem. Key features of the theory are elucidated using a series of three-dimensional numerical examples.