Chapter 2.2 - Biaxial test results for strength and deformation of a range of E-glass and carbon fibre reinforced composite laminates: Failure exercise benchmark data

Abstract

This chapter presents a wide range of experimental data, results, and comments on the experiments, which determine the accuracy of current theories for predicting failure in composite laminates. It outlines the source of data and the methods used in deriving the material properties for the unidirectional laminae and constituents. In some cases where laminates of similar materials are tested in different laboratories, the same set of material properties is employed to minimize the number of data sets issued. It also compares the predictions of 12 different failure theories with experimental data. The experimental data covered 14 test cases involving 0° unidirectional laminae under biaxial direct and shear loads. Other test cases include (a) (90°/ ± 30°)s, (0°/ ± 45°/90°)s, and ( ± 55°)s multidirectional laminates under biaxial loads and (b) stress strain curves for (0°/ ± 45°/90°)s, ( ± 55°)s, ( ± 45°)s, and (0°/90°)s laminates under uniaxial and biaxial loads. It discusses the differences between the symmetric laminated plate models used in the theoretical analysis and the tubular test specimens. Almost all of the experimental results chosen for use in the World Wide Failure Exercise (WWFE) are derived from tests on tubular specimens. Testing of tubes avoids problems associated with free edge effects that are encountered with coupon and other specimens and a wide range of biaxial and triaxial stresses that can be applied by subjecting tubular specimens to combinations of internal or external pressure, torsion and axial load.