I'm looking for true stress vs true strain into the plastic range for FEA modelling of PTFE, UHMWPE, Nylon, Delrin and other seal materials. Anybody have a good source?
Performance of PTFE can be predicted by calculation similar to other engineering materials.
However, just as steel and aluminum properties are different, so, too, is PTFE from other engineering materials.
For tensile stress, stress-strain curves in the usual design temperatures show that yield occurs at high deformation. Elasticity begins to deviate from linearity at strains of only a few percent, like most plastics. Consequently, when working with PTFE or other plastic, it's best to work with acceptable strain and determine the corresponding stress.