Size Effect on Fracture Toughness of Rigid Polyurethane Foams

Abstract:

This paper presents the size effect on fracture toughness of polyurethane foams (PUR 40), with nominal density 40 kg/m3, closed-cell rigid foams widely used for sandwich cores. Determination of the fracture toughness was carried out by three-point bending tests (TPB), on notched specimens, at room temperature (20±2°C). To determine the size effect in Mode I fracture toughness, specimens geometrically similar in two dimensions with length-to-width ratio 5:2 were selected. The specimens were subjected to a quasi-static loading with a speed of 2 mm/min, which was applied exactly on the notch direction. A strong size effect in the closed-cell PUR foam is experimentally demonstrated, by considering a smooth transition between strength of materials approach (with no size effect) and asymptotic case of linear elastic fracture mechanics.

• Periodical: Solid State Phenomena (Volume 188)
• Pages: 205-210
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.188.205
• Online since: May 2012
• Authors: Emanoil Linul, Liviu Marşavina, Tomasz Sadowski, Marcin Kneć
• Keywords: 3 PB Tests, Closed Cells, Fracture Toughness, Mode I Fracture, PUR Foam

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