On Flexural and Tensile Strength for Composites Manufactured by RTM

Abstract

The difference between tensile and flexural strength for a composite con sisting of vinylester reinforced with continuous E-glass fibres arranged in a random pat tern has been investigated. Both tensile tests and three- and four-point bending tests have been performed. It was found that the Weibull theory can be applied to explain the difference between ultimate strength in tension and bending provided that the theory is applied on fibre stress and not on some average composite stress. In addition it was found that influences of friction at the supports and large deflections has to be taken into account as well as nonlinear elastic material behaviour when glass fibre reinforced plastics are tested in bending. Simple closed form expressions which take these effects into account have been derived. A suggestion for proper evaluation of bending tests is presented in sum marized form in Appendix A.

Keywords

bending strength bending test Weibull statistics glass fibres vinyl ester tensile test tensile strength friction large deflections.

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