On the influence of ply-angle on damping and modulus of elasticity of a metal-matrix composite

The central objective of the classical laminate theory is topredict the properties of a laminate having an arbitrary lay-up, taking as its input themeasured properties of an individual lamina. Whereas a fair amount of work has been done concerning the prediction of the laminate stiffness, relatively little attention has been paid to the prediction of laminate damping. A recent model by Ni and Adams[1] fills this gap. The model is not exact and, of necessity, is based on some simplifying assumptions. The objective of this paper is to compare the predictions of their model with the results of a careful and detailed experimental investigation of the problem as it concerns metal-matrix composites. Flexural modulus and flexural damping of a continuous graphite/ aluminum composite of [±θ] s lay-up were measured forθ = 0, 15, 30, 45, 60, 75, and 90 deg. These were compared with the predictions of a slightly modified form of the Ni and Adams model; the model was modified to include theɛ y ,σ y , andτ xy terms which were ignored in the earlier work, where (x, y, z) is the laminate coordinate system. Excellent agreement between the theory and experimental results was observed.