EXPERIMENTAL METHOD TO MEASURE THE IN-PLANE SHEAR MODULUS AND STRENGTH OF UNIDIRECTIONAL GLASS/EPOXY COMPOSITES.

The in-plane shear modulus and strength of unidirectional glass/epoxy composites, using circular-plate specimens with plus or minus 45 degree anti-symmetrical cutouts, are considered. The author uses photoelastic analysis to show that the circular-plate specimen and a simplified specimen have essentially the same critical stress state. The two types of specimens lead essentially to the same in-plane shear modulus and strength for glass/epoxy composite. Thus the simplified specimen can replace the circular-plate one for such testing, resulting in reducing the machining time by 2/3 and reducing the composite material required by 5/6.