Interpretation of Scaling of Damage and Failure in Fiber Composite Laminates

Abstract

It is often useful to predict the behavior of large structures from the results of tests on subscale articles. While the scaling of the linear elastic response of fiber composite structures is at least reasonably well understood, scaling of damage formation and failure is relatively unexplored. Idealized models of failure processes predict various effects of changes in size. Extrapolation of failure results with size thus requires proper interpretation of the failure mechanisms involved. A series of impact tests was recently carried out in which scaling with respect to size was a primary variable. An analysis of the data from these tests indicates a number of important results with respect to the models of failure mechanisms mentioned above. A primary result is that propagation of delamination closely follows the dependence on absolute size predicted by fracture mechanics and energy release rate analyses. Conversely, fiber breakage does not appear to show a dependence on absolute size. The primary thrust of the paper is to assess the implications of the experimental results in terms of the failure models and the effect on scaling of results.