Statistical properties of microcracking in polyurethane foams under tensile test, influence of temperature and density

• Published in: International journal of fracture 2006-07, Vol.140 (1-4), p.87-98
• Main Authors: DESCHANEL, S, VANEL, L, VIGIER, G, GODIN, N, CILIBERTO, S
• Format: Article
• Language: English
• Subjects: Acoustics; Condensed Matter; Crack initiation; Cross-disciplinary physics: materials science; rheology; Density; Divergence; Exact sciences and technology; Experiments; Failure; Foams; Fracture mechanics; Fracture mechanics (crack, fatigue, damage...); Fundamental areas of phenomenology (including applications); Materials Science; Materials testing; Mechanics; Mechanics of materials; Microcracks; Physics; Plastic foam; Plutonium; Polyurethane foam; Power law; Solid mechanics; Strain rate; Structural and continuum mechanics; Tensile tests
• ISSN: 0376-9429; 1573-2673
• DOI: 10.1007/s10704-006-0051-1

We report tensile failure experiments on polyurethane (PU) foams. Experiments have been performed by imposing a constant strain rate. We work on heterogeneous materials for whom the failure does not occur suddenly and can develop as a multistep process through a succession of microcracks that end at pores. The acoustic energy and the waiting times between acoustic events follow power-law distributions. This remains true while the foam density is varied. However, experiments at low temperatures (PU foams more brittle) have not yielded power-laws for the waiting times. The cumulative acoustic energy has no power-law divergence at the proximity of the failure point which is qualitatively in agreement with other experiments done at imposed strain. We notice a plateau in cumulative acoustic energy that seems to occur when a single crack starts to propagate.