Interrogation of composite structures for inherent damage is investigated by implementing a three-tier analysis scheme. The analysis starts at the structure level where a general-purpose Finite Element code ABAQUS is employed to obtain the stress field in the second level of analysis which is the composite laminate. A special material routine is prepared to propagate the local fields to the individual plies and hence to the third level of analysis which is the microstructure modeling of the composite. Through the third level of analysis, interface damage between fiber and matrix is checked implementing a certain failure criteria. The interaction between the different length scales; that are, structure, macro, and micro scales, is implemented using the non-mechanical strains caused by damage. Embedment of electrically active fibers in the laminate serves as a tool to interrogate the structure for inherent damage through the electric displacement generated due to the electro-mechanical coupling. To verify the developed multi-scale model, a comparison with the experimental results of a tube problem under combined internal pressure and axial load is presented. The results show good agreement in both the undamaged and damaged state. As an application, a plate with a hole under biaxial load is solved. The output includes not only the structure's global behavior during damage but also detailed information about the location of damage within the structure, the plies that exhibit damage, the type of damage and the fiber/matrix debonded length. A comparison between the electric displacement of the active fibers in the undamaged and damaged states is presented as well.
Micheal, Amany and Bahei-El-Din, Yehia, "Implementation of multiscale mechanisms in finite element analysis of active composite structures" (2022). Centre for Advanced Materials. 22.