Experimental and numerical analysis of the effect of temperature on the mode I and mode II delamination of glass fiber woven composites

Abstract

This work focuses on investigating the effect of short-term changes of temperature on the mode I and mode II glass fibers woven composite interleaved with layers of chopped strand mat (CSM). Existing experimental and numerical methods are critically applied to characterize and model the delamination of the woven-CSM composite laminate. Double cantilever beam (DCB) and end notched flexure (ENF) tests are performed in non-post cured and post cured specimens at room temperature (21 °C), and the operational conditions are investigated on post cured specimens tested in low (−10 °C) and high (70 °C) temperatures. The fracture behavior is characterized using the compliance-based beam method (CBBM) while crack length estimations based on the specimen compliance are compared to direct measurements from digital image correlation (DIC). Then, a failure analysis was performed using an optical profilometer and scanning electron microscopy (SEM). Temperature changes affected the preferential crack path for the woven composite delamination in mode I loading conditions. However, the crack path in mode II fracture remained independent of the testing temperature. Fractography results revealed temperature-dependent failure mechanisms, with an increase of fiber/matrix interface debonding and matrix deformation in higher temperatures. The higher matrix ductility translated into an improvement of the delamination fracture toughness in both mode I and mode II loading conditions. Finally, non-linear cohesive models directly derived from experimental results were capable to accurately reproduce the mode I and mode II delamination fracture behavior of the woven-CSM composite in different temperatures.