Experimental reexamination of transverse tensile strength for IM7/8552 tape-laminate composites

Abstract

Due to the observed dependence of transverse-tensile strength, Y T, on test geometry and specimen size, there is no consensus regarding a test method that can uniquely measure Y T. This study reexamines the characterization of Y T by comparing results from established flexure tests with results from a new tensile test that exhibits consistent failure in the gage region. Additionally, the effects of surface preparation and direction of transverse fracture are investigated. Results show that Y T is inversely proportional to specimen volume and surface roughness and is insensitive to direction of transverse fracture. The relationship between specimen volume and Y T is adequately captured by Weibull strength-scaling theory, except at the tails of the Y T distributions. However, specimens exhibited microcracking prior to failure, which violates the “weak-link” assumption of the Weibull theory. These findings highlight the challenges of using deterministic Y T values in progressive damage analysis.

Effect of interface and matrix strength on transverse tensile strength of unidirectional CFRP composite

“…The interface controls the stress and strain transfer of the fiber and matrix [5,6]. The failure of interface is an important factor that causes composite transverse fracture [7,8]. However, traditional micromechanics models such as the Mori Tanaka model [9], self-consistent model, and bridging model [10] are based on the perfect interface assumption, ignoring the influence of interface on the mechanical behavior of CFRP.…”