Strain-Rate-Dependent Failure Criteria for Composite Laminates: Application of the Northwestern Failure Theory to Multiple Material Systems

The strain-rate-dependent matrix-dominated failure of multiple fiber-reinforced polymer matrix composite systems was evaluated over the range of quasi-static (10⁻⁴) to dynamic (10³ s⁻¹) strain rates using available experimental data from literature. The strain rate dependent parameter, m, was found to relate strain-rate dependent lamina behavior linearly to the logarithm of strain rate. The parameter was characterized for a class of laminates comprised of epoxy-based matrices and either carbon or glass fibers, and determined to be approximately 0.055 regardless of fiber type. The strain-rate-dependent Northwestern Failure Criteria were found to fit all data in superior agreement to classical approaches across all strain rates evaluated based on solely lamina-level properties. It was determined that using the determined m value with the Northwestern Failure Criteria provided an accurate prediction of material behavior regardless of fiber type for the identified material class, which significantly reduces the material characterization testing required for the typical building block approach used by industry for computational analysis validation.