Optimal Hole Shapes in Composite Structural Elements Considering Their Mechanical and Strength Anisotropy

A method for selecting the optimal shape of holes, taking into account the strength anisotropy of composites, is proposed. The methodology includes the following: an algorithm for stress determination based on singular integral equations and Green’s solutions; a strength criterion for the boundary of unloaded holes, which takes into account the anisotropic mechanical and strength properties of composites; an algorithm for determining hole shapes by a formulated nonlinear programming problem. The results of the research are presented for holes of various shapes, including single- and double-periodic hole systems. It is established that the calculated allowable loads for composite plates with holes based on stress concentration factors can be significantly overestimated. At the same time, by designing holes of optimal shape, the allowable loads can be many times greater than those for circular holes.