Mapping the nonlinear crack tip deformation field in soft elastomer with a particle tracking method

Long, Rong; Zou, Zhanan; Qi, Yuan; Xiao, Jianliang

Citeable URL: https://scholar.colorado.edu/concern/articles/zk51vh872

Abstract

Stretchable and fracture-resistant elastomers or gels are highly desirable in a wide range of existing and emerging applications. Fracture of soft materials, especially the ones with significantly enhanced toughness, typically involves severe deformation near the crack tip. However, experimental characterization of the crack tip deformation field in soft materials has been challenging due to its highly non-uniform and nonlinear nature. This is an important limitation towards a complete understanding of the intricate mechanics involved in soft material fracture. In this paper we present experimental data of the nonlinear, multiaxial crack tip deformation field obtained by tracking randomly distributed tracer particles. Specifically, we measured the fields of displacement and deformation gradient around the tip of a Mode-I crack in a soft silicone elastomer. We experimentally observed, for the first time, a region of validity for the asymptotic solution of crack tip deformation field in hyperelastic solids with strong strain stiffening. Furthermore, the measured crack tip deformation field enables local evaluation of energy release rate through the J-integral, which can remove the requirement of specific experimental geometries, such as the pure shear fracture test, to measure the fracture toughness. It also enables determination of the
true crack extension length defined in the reference configuration. Based on these two capabilities, we were able to measure the crack growth resistance behavior and the ratedependence of fracture toughness for soft materials with highly blunted cracks.

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