Evaluation of the cyclic fatigue performance of polyurethane foam in different density and category

In this study, the cyclic fatigue performance of six different polyether type of polyurethane foams was investigated. The foams were first subjected to indentation force deflection (IFD) and 8000 cycles fatigue loading according to ASTM D3574-11. The second measurement of IFDs of the foams were carried out to observe the changes after 8000 cycles loading. Then, the foams were subjected to 80000 cycles loading. The final IFDs of the foams were measured, and the changes in the IFD, foam firmness, and thickness of the foams were determined. The results showed that increasing the density of the normal foam from 14 to 28 kg/m(3) reduced the 25% IFD loss values of the foams from 30.7% to 21.5%, which increased foam firmness. However, increasing the density of the soft foam from 24 to 32 kg/m(3) insignificantly increased the IFD loss values from 20% to 23.6%, which decreased the foam firmness. The support factors of both the normal and soft foams increased as the density increased after the loadings. Generally, no visual deformation was observed for the foams.