Variation of In-Plane Elastic Constants in Material Design of Composite Laminates

Abstract

Two important problems are discussed in this paper with respect to the material design of composite laminates. One of them is the selection of optimal constitution of laminates from the viewpoint of the statistical variation of orientation angle. The other is concerned with the problem of the degree of accuracy of lay-up fabrication process.
The variation sensitivity of in-plane elastic properties was studied statistically. The effect of the variation of orientation angle on effective engineering elastic constants is investigated by the partial derivative and Monte Carlo simulation technique. In addition, the effect of number of plies on standard deviation of in-plane elastic constants was studied. These sensitivity studies are summarized as follows.
(1) The difference in constitution of laminates considerably affects the sensitivity of the variation of effective engineering elastic constants to the orientation angle. Therefore, from these equivalent constitutions, one can select the optimal constitution taking account of statistical sensitivity of in-plane elastic constants.
(2) The procedure to evaluate the influence of the number of plies on the standard deviation of elastic constants was presented.
(3) The proposed evaluation procedure suggests a method how to fabricate the composites having the variation of elastic constants less than a required value.