Polyurethane foams: effects of specimen size when determining cushioning stiffness

Polyurethane (PU) foams are used as inexpensive materials for reducing interface pressure in a number of rehabilitative applications, particularly seating and prosthetic limb interfaces. Specimens of three different PU foams were cut to four different sizes and compressed according to ASTM protocols to determine their stiffness capabilities. It was found that the test results varied according to the relationship between the size of the test specimen and the test indenter. It is recommended that investigators create a testing situation that reflects their application when determining the cushioning capabilities of these materials.