Determination of in-plane shear properties by three-point flexure test of ±45° anti-symmetric laminates

The aim of this work is to propose a new method for determining both the in-plane shear modulus and the in-plane shear strength of composite materials by using three-point flexure tests on [±45] angle-ply laminates. Symmetric and anti-symmetric configurations have been analysed by Classical Laminated Plate Theory. The anti-symmetric configuration has been considered more suitable than the symmetric one, due to the absence of bending/twisting coupling effects. Three-point bending tests have been performed on [±45] anti-symmetric laminates of AS4/8552 carbon/epoxy material. Experimental results obtained by flexure tests in anti-symmetric laminates agree with the values attained by tensile tests on symmetric laminates, and with values reported in literature. Experimental conditions for determining in-plane shear properties by using the anti-symmetric three-point bending method are recommended.