Random Fiber-Matrix Model for Predicting Damage in Multiscale Analysis of Textile Composites under Thermomechanical Loads

摘要

Failure prediction in structures containing carbon fiber polymer matrix composites is complicated by the various scales at which damage and failure can occur. In order to understand and predict how a composite structure will fail under a complex thermomechanical load, a variety of mechanisms at different scales must be taken into account. At the microscale, where fibers and matrix are modeled as discrete constituents, temperature changes induce stresses due to the thermal expansion mismatch between the constituents. Interactions between these thermally-induced stresses and stresses from mechanical loading change the apparent strength of tows or laminas when observed at larger scales. Failure at the microscale is further complicated by the inherent randomness that characterizes the arrangement of individual fibers. This leads to enhanced stress concentrations where fibers are in very close proximity to one another. These stress concentrations will have a significant effect on extreme-driven phenomena such as failure. At the intermediate scale (often referred to as the meso-scale) in which the fibers and matrix are homogenized, but individual tows (or lamina, in the case of tapes) are modeled discretely, thermal loads can further influence whether a given mechanical load will cause failure. This is due to thermallyinduced stresses that arise from the thermal expansion mismatch between the different tows and the neat matrix pocket.