Evaluating Damage with Digital Image Correlation: C. Applications to Composite Materials

The present chapter is devoted to the evaluation of damage with digital image correlation (DIC). Applications will focus on composite materials. The latter ones are designed to accommodate microcracks through suited microstructures. As such, they constitute a natural class of materials for which damage (or rather damages) is an essential feature of their mechanical behavior. As discussed in a previous chapter (addressing detection of physical damage), DIC can reveal the elementary mechanisms (e.g., dense distribution of microcracks, crack branching along weak interfaces, progressive debonding of interfaces, and subsequent pullout or delamination). It will also be shown that damage laws can be identified with the help of DIC from mechanical tests imaged at different stages of loading. The followed strategy will be seen as reminiscent of the one that was used in the previous chapter dedicated to 1D (i.e., beam like) geometries (from physical to mechanical damage). Here, it will be necessary to couple DIC with finite element models. The benefit will be that in addition to the identified law, a full validation is naturally offered from the highly redundant piece of information contained in the measured displacement fields.