Experimental investigation of progressive damage and the effect of layup in notched tensile tests

The presence of subcritical damage in notched composites significantly affects the ultimate failure mode and strength. This article presents a detailed study of four different layups of E-glass/913 tested using a double-edge-notched specimen loaded in tension. For each layup three different in-plane dimensions are tested. Results are presented in terms of failure mode, strength, and subcritical damage development. Subcritical damage development is consistent between the layups and between scaled specimens of a single layup. Ultimate failure, however, shows some variations both with layup and size and this is examined in some detail. The trend of decreasing strength with increasing specimen size is observed for all cases except those where there is a change in failure mode between different size tests. The strengths are compared with predictions from two analytical techniques, which show some ability to achieve correlation across a subset of the test data. Correlation is not possible where variations in failure mode occur for a single layup.