Continuum Damage Mechanics (CDM) based progressive damage and failureanalysis (PDFA) methods have demonstrated success in a variety of finite elementanalysis (FEA) implementations. However, the technical maturity of CDM codes hasnot yet been proven for the full design space of composite materials in aerospaceapplications. CDM-based approaches represent the presence of damage by changing thelocal material stiffness definitions and without updating the original mesh or elementintegration schemes. Without discretely representing cracks and their paths through themesh, damage in models with CDM-based materials is often distributed in a region ofpartially damaged elements ahead of stress concentrations. Having a series of discretematrix cracks represented by a softened region may affect predictions of damagepropagation and, thus, structural failure. This issue can be mitigated by restricting matrixdamage development to discrete, fiber-aligned rows of elements; hence CDM-basedmatrix cracks can be implemented to be more representative of discrete matrix cracks.This paper evaluates the effect of restricting CDM matrix crack development to discrete,fiber-aligned rows where the spacing of these rows is controlled by a user-defined crackspacing parameter. Initially, the effect of incrementally increasing matrix crack spacingin a unidirectional center notch coupon is evaluated. Then, the lessons learned from thecenter notch specimen are applied to open-hole compression finite element models.Results are compared to test data, and the limitations, successes, and potential of thematrix crack spacing approach are discussed.
展开▼
