Quantitative Photothermal NDE of Composites: Numerical Analysis

Photothermal non-destructive evaluation (NDE) of solids is a powerful method to detect subsurface cracks, inclusions and delaminations. To fully explore the use of this method, and to expand its capabilities a quantitative measurement model is required. Such a model provides the link between the actual damage processes in the material or structure under investigation and the measurement system response. In the proposed paper a numerical simulations of the photothermal non-destructive evaluation of unidirectionally reinforced composite materials. In the investigation, special focus is placed on the description of the interaction of the thermal field with the delamination to be detected. The model consists of two main parts: (1) a probabilistic crack advance and crack bridging model embedded in a full field solution of the actual loaded structure, and (2) a model describing the thermal characteristics of the bridged delamination in dependence of the loading state and the probabilistic fiber failure model. The paper will describe results on computationally predicted thermal response data in dependence of the type and magnitude of the applied loading for the case of ceramic matrix composite materials.