Residual strength estimation of a laminated composite with barely visible impact damage based on topology optimization

The purpose of this study is to develop an approach to generate reasonably conservative estimations of the residual strength of a composite material with barely visible impact damage (BVID) without directly modeling the dynamic impact process. During an impact, a portion of the impactor kinetic energy transforms into the formation of a microcrack system in the matrix, fiber, and interface, which can be interpreted as material damage. Using the estimated value of energy transformed into damage as a constraint in the mathematical formulation, the optimization algorithm computes the damage distribution to minimize the residual stiffness of the structure as an objective function, which is closely related to the residual strength. Thus, this procedure gives “the worst” possible damage distribution within the material as a conservative estimation of the residual strength of the composite part. The proposed approach is promising for establishing the allowable BVID with fewer experiments.