Abstract
In this paper we present a methodology to measure the material traction-separation relation for a poly(ethylene carbon monoxide) copolymer, ECO. This material exhibits a ductile-to-brittle transition when subjected to ultraviolet irradiation and undergoes a change of failure mechanism, from shear yielding to crazing, in the process. Single edge notched tension specimens of ECO irradiated for 50 h were used to generate slow-speed stable crack growth, predominantly from material crazing. Full-field measurements of the in-plane deformation around the growing crack tip were performed using the optical technique of digital image correlation. A multicamera setup was used in which simultaneous measurement of both the far-field displacement and that directly surrounding the craze was performed. The far-field results were used to obtain a value of the energy release rate supplied to the crack tip region. The near-tip results were used to extract a material traction-separation law in the regime of steady-state crack growth. A softening traction-separation relation was measured. The area under the traction-separation curve was then compared with the simultaneous far-field measurements and the agreement was very good (within 6.5%) validating the experimental methodology used.
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Abanto-Bueno, J., Lambros, J. Experimental determination of cohesive failure properties of a photodegradable copolymer. Experimental Mechanics 45, 144–152 (2005). https://doi.org/10.1007/BF02428187
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DOI: https://doi.org/10.1007/BF02428187