Failure of foamed elastic materials

摘要

AbstractA theoretical treatment is given which predicts the tear strength of a foamed elastic material. The energy required to break a test‐piece in simple extension is also calculated, on the assumption that tensile failure occurs by catastrophic tearing from a small nick of a similar size to the largest pore present in the test‐piece. The behavior is given in terms of the strength of the matrix, the density of the foam, and the pore size. Measurements of the tear strength, tensile strength, and elongation at break are described for natural rubber foams prepared from latex. A wide range of density is covered (0.09–0.5) giving a variation in tear strength of 9 : 1 and in work‐to‐break of 24 : 1. Satisfactory agreement with theory is found in both cases, indicating that the basic concepts of the modes of failure are correct. It is concluded that uniformity of pore size is required for maximum strength, and a large average pore size for high tear r