Prediction of the Degradation of Composite Materials for Emerging Army Facilities

An innovative methodology, based on mechanistic models, will be developed for prediction of long-term (25+ years) durability of composites for the US Army’s emerging facilities in different climatic zones. Accelerated testing simulating the Army’s composites applications in various constructions and fields will validate it. Phase I will develop the basic predictive model using the in-house NOVA-3D computer code and will use Arrehenius principles adapted to the TTS (Time Temperature Superposition) for experiment design to measure composites degradation under simultaneous UV (Ultra Violet), stress, and hygrothermal exposure. The test will capture the synergistic effects of field exposure and extreme temperatures, viz., hot/dry, hot/wet, cold/dry, and cold/wet. The capacity loss from changes at the molecular level, such as hydrolysis, microcracks, and UV induced polymer chain-scission, will be incorporated in the model using a unique finite-element (FE) based multi-scale, multi-mechanism degradation model that was developed in-house. Phase II will refine the model to include additional chemical degradation mechanisms, relaxation and creep threshold, stress induced crack growth in fibers and fiber/matrix debond, and dynamic effects of blast and seismic events. The model will predict service life and remaining life and will be incorporated in a user-friendly Field Usable Design Tool software, to be commercialized in Phase III.