Virtual Testing for Advanced Aerospace Composites: Advances and Future Needs

In this paper, the conceptual, experimental, and computational challenges associated with virtual testing have been discussed and recent advances that address these challenges have been summarized. The promising capability of augmented finite element method based numerical platform for carry out structural level, subply scale, and microscopic single-fiber level analyses with explicit consideration of arbitrary cracking has been demonstrated through a hierarchical simulation-based analysis of a double-notched tension test reported in the literature. The simulation can account for the nonlinear coupling among all major damage modes relevant at different scales. Thus, it offers a complete picture of how microdamage processes interact with each other to eventually form a catastrophic major crack responsible for structural failure. In the exercise of virtual testing, such information is key to guide the design of discovery experiments to inform and calibrate models of the evolution processes. Urgent questions derived from this exercise are: How can we assure that damage models address all important mechanisms, how can we calibrate the material properties embedded in the models, and what constitutes sufficient validation of model predictions? The virtual test definition must include real tests that are designed in such a way as to be rich in the information needed to inform models and must also include model-based analyses of the tests that are required to acquire the information. Model-based analysis of tests must be undertaken and information-rich tests must be defined, taking proper account of the limitations of experimental methods and the stochastic nature of sublaminar and microscopic phenomena.