specimens) were also tested. The ratio of the specimen height above the notch to that below it is 2 (cf. Fig. 4.), and an unloaded specimen is shown in Figs. 4 and 5. In the asymmetric specimen, the mode mixity initiated as soon as the crack started propagating. Also, the diameter of the holes was reduced to 3.2mm (1/8’’) to make room Fig. 4. PMMA asymmetric CT specimens with w=25.4mm (1’’), a=12.7mm (0.5’’), and the ratio of the specimen height above the notch to that below is 2; B, specimen thickness = 12.7mm (0.5’’). (All dimensions in mm). Fig. 5a. Asymmetric CT specimens with notch and initial crack for the notch in the narrower arm of the asymmetric geometry. Because of the mode mixity, the crack path was inclined in the direction of the smaller arm (on the top in Fig. 5b). However, the crack path changed direction and became straight (almost perpendicular to the right edge in Fig. 5b) when the crack approached the edge. Additional details on this observation will be discussed in the section on the numerical study and comparisons will be made with the computed results. 16
RkJQdWJsaXNoZXIy MTMzNzEzMQ==