Stress-Strain State of Multilayer Composite Laminates

A quantitative treatment of the stress-strain state of a multilayer composite is presented, with particular attention given to the role of edge effects. The quantitative analysis indicates that, in addition to the usual stresses, the edge zones of a multilayer element are subjected to tangential stresses acting at the surface between the base material and the adhesive. However, this stress-strain analysis fails to explain the observation that the strength of a multilayer composite is greater than that of its base material. Accordingly, a strengthening effect due to the influence of the adhesive in crack initiation and propagation is introduced to render the model more accurate.