Determination of the critical crack length of notched weft-knitted glass fiber variable width composite plates

In this study, the critical crack length (CCL) of the knitted composite plates with different central holes and different plate width were predicted by means of point stress criterion, (PSC), and average stress criterion, (ASC). The knitted fabrics used for the study are fabricated from the 200 tex glass yarn with epoxy resin and cured in a hot press machine. Specimens with 10, 20 or 40 mm width (W) and containing 2, 3, 4 or 5 mm diameter holes (D) were prepared for two configurations and then tested. The CCL found through the stress criteria from the experimental data. The CCL data are plotted with respect to D/W ratios and then logarithmic curves were fitted to the data by using curve fitting technique. The results show that the CCL depends on the hole size as well as width of the plate. In addition, the CCL curves obtained by curve fitting technique give the same character and also it can be observed that there is a correlation between the curves. As a result of that the CCL can be predicted by anyone by using the less experimental data.