Failure of Carbon Fibers at a Crease in a Fiber Reinforced Silicone Sheet

Abstract

Thin sheets of unidirectional carbon fibers embedded in a silicone matrix can be folded to very high curvatures, as elastic microbuckles with a halfwavelength on the order of 1 mm decrease the maximum strain in the fibers near the compression surface. This paper shows that probabilistic failure models derived from tension tests on individual fibers can be used to predict accurately the value of the outer surface curvature of the sheet, at which a small percentage of fibers break when a crease is formed in the sheet. The most accurate results are obtained by using a strainbased Weibull distribution of the failure probability in tension.