Abstract:

Based on the fatigue failure mechanism of unidirectional off-axis laminate and Hashin fatigue failure criterion, a method of estimating the in-plane shear S-N curve from the off-axis tension S-N curve of unidirectional laminate is presented and then the S-N curve of unidirectional laminate with arbitrary angle can be predicted based on the estimated in-plane shear S-N curve and the longitudinal/transverse S-N curve. This is verified by experimental results with four kinds of composites. It is found that the in-plane shear S-N curves estimated from the off-axis tension S-N curves of unidirectional laminates with different angles are consistent with each other and the predicted S-N curves of the these laminates agree well with experimental results.

Key words: composites, laminates, fatigue life, in-plane shear, S-N curve