Notch stress concentrations and failure characteristics in laminates with triple parallel notches

This paper deals with stress concentrations in laminates with triple parallel-arranged and equally spaced notches. By the use of the finite-element method, the stress concentration factors at points on the boundary of a notch were calculated for unidirectional and cross-ply laminates and for isotropic plates with surface or through notches. It was found that the stress concentration factors near the notch change from high to low then revert to high with spacing between both neighboring notches for all the calculated cases. A series of failure tests on carbon-fiber/epoxy laminate specimens with triple notches were conducted. The test results validated the calculated results.