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摘要
Polyvinyl alcohol (PVA) sponge with a complex interconnecting porous structure indicates suitable mechanical properties at different strain rates. The paper presents the first scientific study to show how different results are given by the various definitions of stress-strain used and to recommend a specific definition when calculating the energy absorption characteristics of the PVA sponge. A series of tensile tests on PVA sponges are carried out. Three stress definitions (second Piola-Kirchhoff stress, engineering stress, and true stress) and four strain definitions (Almansi-Hamel strain, Green-St. Venant strain, engineering strain, and true strain) are used to determine the modulus of resilience and modulus of toughness. The stress-strain curves of PVA sponges show a near constant plateau stress over a long strain range, which is ideal for energy absorption applications. The results reveal that the Green-St. Venant strain definition has the highest modulus of resilience (3000 J/m(3)) and toughness (56,900 J/m(3)) at different definitions of stress and may overestimate the modulus of resilience and toughness. The Almansi-Hamel strain definition exhibits the lowest modulus of resilience (1760 J/m(3)) and toughness (4850 J/m(3)) at different stress definitions and may underestimate these values. The results also show that the effect of varying the stress definition on the modulus of toughness measurements is significant but not when calculating the modulus of resilience. The true stress-true strain definition favors spongy material mechanics since it gives more accurate measurements of the sponge%26apos;s response using the instantaneous values.
- 出版日期2014-12
