The present paper presents the crack growth behavior of vulcanized natural rubber under fatigue loading. Our research focuses on the crack tip morphology evolution and its relationship with crack growth rate. For this purpose, an original real-time monitoring apparatus is employed to capture the crack tip morphology during standard fatigue testing. This method involves the use of a high speed microscopic camera and a dynamic mechanical analyzer with crack growth testing function. The tear energy (T) dependence of crack tip morphology is analyzed. It reveals that there are two characteristic cracking morphologies: at T < 600 J/m2, the power law slope of crack growth rate (dc/dn) versus T is 6. Surface peeling at the crack-front surface occur, which result in the appearance of secondary cracks; at T > 600 J/m2, the power law slope of dc/dn versus T is 2. The breaking-up of ligaments seems to be the mechanism of crack propagation. The result can be seen in Figure 1 . This work gives us new opportunities to study the crack growth mechanism of rubbers in the viewpoint of real-time crack tip morphology investigation.

Crack growth mechanism of natural rubber under fatigue loading studied by a real-time crack tip morphology monitoring method

248th National Meeting (2014)

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