Elastic properties of plastic laminates with particular reference to shear modulus
Williams, D. G. (Donald G.)
Sims, James R.
Master of Science
Previous work indicates that shear properties of plastic laminates are a function of the shear properties of the bonding resin and therefore largely independent of the plane of the laminate. Direct and indirect tests involving shear properties in all planes of two similar, half inch thick hand lay-up panels, were conducted to test this hypothesis. The main correlation was made on the basis of apparent elastic modulus in simple bending as a function of span-depth ratio. Curves for this value were calculated using an elastic solution accounting for load concentration effects. This calculation was made for various values of shear modulus as obtained by direct and indirect tests. Conclusions were drawn from a comparison of these curves, and an experimental curve for simple bending tests over four span-depth ratios. In the latter tests, curvature was transverse to the plane of the laminate and so therefore were shear effects. Direct tests for shear modulus proved unsatisfactory, but the comparison of calculated apparent modulus, for shear modulus in the plane of the laminate, agreed within 2% of the experimental curve. It is thought that further work will indicate that a single value of shear modulus will suffice for design purposes.