Publications

Full-field characterization of tensile and fracture behavior of a rigid polyurethane foam using digital image correlation

Hong, Soonsung H.; Jin, Helena; Lu, Wei-Yang L.

Tensile deformation and fracture behavior of a closed-cell rigid polyurethane foam, called TufFoam, were investigated. During uniaxial tension tests and fracture mechanics tests, full-field deformation measurements were conducted by using digital image correlation technique. Uniform deformation fields obtained from the tension tests showed that both deviatoric and dilatational yielding contributed to the nonlinear deformation of the foam under tension. Fracture mechanics tests were performed with single-edge-notched specimens under three-point bending and uniaxial tension. A moderate specimen-size and loading-geometry dependence was observed in the measured fracture toughness values based on linear elastic fracture mechanics. Full-field deformation data near the crack-tip were used to investigate stable crack-growth in the foam until unstable fracture occurs. The path-independent J-integral and M-integral were calculated from elastic far-fields of the experimental data, and used to obtain crack-tip field parameters, such as crack-tip energy release rates and effective crack-tip positions. The combination of the full-field deformation measurement technique and the path-independent integrals was proven to be a useful approach to measure the initiation toughness of the foam that is independent of the specimen size and loading geometry. © 2008 Society for Experimental Mechanics Inc.