An Experimental Study of Failure in Circumferentially Notched Elastomer Cylinders
Abstract Cylindrical dumbbell specimens containing deep circumferential cracks were loaded in tension until failure to investigate the fracture process in thick carbon black filled elastomers. Failure occurred at large deformations and was characterized by material tearing and small amounts of slow stable crack extension until rupture. The tearing process itself consisted of two distinct phenomena, delamination and crack extension. Upon load application, parabolic and asymmetric blunting of the crack tip was observed followed by a visible separation of the fabricated crack surfaces into upper and lower crack surfaces connected by an inner core of elastomer material. Localized material failure, identified as delamination, occurred along the outer surface of this inner core between the fabricated crack surfaces. Crack extension in the load direction was found above and below the fabricated crack surfaces. Both qualitative and quantitative aspects of failure were studied. Load and crack mouth opening displacement (CMOD) histories were examined, and the stretch ratio and tearing energy at rupture were measured. Finally, a model describing the tearing process was discussed.