Woven composite design for extreme events using a damage mechanics methodology

Abstract

Abstract

Current predictive techniques for the analysis of composite structures and components near and beyond their ultimate strength are simplistic, using basic failure functions and traditional failure envelopes to determine the degree of damage in some arbitrary composite component or structure subjected to a biaxial or triaxial loading regime. Similarly, the design procedure usually assumes that the composite structure remains elastic throughout any potential applied loading.

The analysis methodology proposed in this paper reflects a state-of-the-art dynamic modelling technique based on finite elements (FE) that can be used to model a wide range of problems, from extreme events, such as an explosion, to non-linear static problems that can occur near discontinuities or free edges.

The damage mechanics approach presented in this paper uses a scalar damage variable assigned to each observed damage mode. As damage is cumulative and related to the engineering constants, such as the Young's modulus, the technique allows initial and/or post-dynamic static loads to be applied to the composite structure or component, so potentially a cradle-to-grave composite design methodology could be developed.

The forms of the stress-strain curve for woven glass composite and the relevance of experimentally measured material damage constants are discussed. The proposed damage mechanics approach has been implemented as a new material failure model in the explicit dynamic DYNA3D FE code. Results are presented for two high-velocity (bird strike) impact events on a woven glass composite.