Effect of Notch-Induced Strain Gradients on the Applicability of Multiscale Approaches for Woven Composites: Combined Experimental and Computational Investigation

摘要

Woven composites are widely used in the aerospace and wind energy structures due totheir high strength to weight ratio and their ability to conform to irregular shapes betterthan unidirectional composites. These structures frequently contain stress risers suchas notches, fasteners, and pre-existing damage, all of which can act as failurenucleation points. The complexities associated with accurately modeling damageinitiation and progression in woven composites have led to the development ofmultiscale models for this class of materials. However, the intrinsic size of the tows ina woven composite is often of the same order as the size of defect features in thesestructures, which can invalidate many multiscale assumptions that are typically usedand have been shown to work well in unidirectional composites. For wovencomposites, the problem is identified for 12k RVE size by comparing computationallycalculated and experimentally determined OHT strengths. In our previous work weutilized a multiscale modeling approach to quantify a critical regime around a hole inan open-hole tension (OHT) test [1]. In the current study we conduct an experimentalinvestigation to compare with finite element analysis. For each OHT test, [0]_n and[0/45]_(ns) layup is manufactured. OHT tests are performed for two ratios of hole-size toRVE size. Strains calculated from Digital correlation analysis are plotted across thehole perpendicular to loading directions. These strains and strain gradients arecompared with quantities calculated with homogenized model and discrepancies arediscussed.