Abstract
In this paper, a fatigue life prediction method based on linear fracture mechanics is proposed to composite materials. In order to evaluate this method, the cyclic loading tests of graphite/epoxy composites plates with [±30]s, [±45]s and [±60]s laminate orientations were carried out.
It was revealed that the computational result was satisfactory agreement with the experimental ones except long life region [±30]s laminate orientations. The fracture mode was the combination of tension and shear modes when the angle between loading direction and fiber orientation became small. Therefore, it is recognized that the long life prediction of these materials has to require fracture mechanics base on the combined mode which is not dealt with in this paper.
Furthermore, the effects of material properties on fatigue life were investigated as an application of the proposed model to material design. As a result, it became clear that the fatigue life is affected by the ultimate tensile and shear strengths of the matrix and depends strongly on the influence of initial crack length that is calculated from the size of voids or defects.
