A dynamic crash model for energy absorption in braided composite materials. Part I: Viscoplastic material model

A dynamic crash model is developed and implemented to model the failure behavior and energy absorption of braided composite structures. Part I describes the development and theoretical foundation of a viscoplastic material model that captures the rate-dependent behavior present in braided composite materials. Part II presents the implementation of the model into a FEM program and contains experimental results for tubes crushed from quasi-static rate to 4000 mm/s rates used to verify the model. The model is presented from the mesoscale to the structural scale, starting with the constitutive model applied to composite tow segments. Tow segment response is homogenized to determine the response of the braided unit cell, while consideration for braider tow rotation and stress concentration appear at the structural level.