Book Description

With the continued success of composite materials in high performance structures, new applications for Navy primary structure are being identified. Many of these applications require designs with composite materials having section thicknesses greater than those that have been used and studied to date. Along with this interest in thick composite structures comes the need for full three-dimensional stress analysis. The limits and accuracy of existing three- dimensional data bases will dictate the limit and accuracy of corresponding analyses. This report summarizes an investigation of the through-thickness strain response of thick composite materials subjected to compressive loading. One-half inch thick (96 ply) carbon and S2 glass reinforced composites were studied. A thick-section compression test method has been developed for the purposed of this investigation. Using this test method the longitudinal and through-thickness strain to failure, longitudinal modulus, inplane and through- thickness Poisson's ratio, and ultimate strength of these materials have been determined. The through-thickness data from the 96 ply 0 coupons show the materials to be transversely isotropic. The through-thickness data from 96 ply 0/0/90 laminates show good correlation with a theoretical solution that provides the nine elastic constants for thick orthotropic plates.