Rate-dependent mechanical characteristics of polytetrafluoroethylene (PTFE) gaskets under cyclic pulsating compression

Accumulated deformations of polytetrafluoroethylene (PTFE) gaskets under cyclic stress-controlled compressive loads considering temperatures and stress rates are tested. Results present that the accumulated compressive deformation of PTFE gaskets becomes load rate independent when the stress rate is less than 0.1 MPa/s under various temperatures. The compressive deformation accumulates during the initial 50 or more cycles, but it always turns to shakedown subsequently under the experimental conditions. Moreover, the accumulated strain is sensitive to temperature due to material softening and time-dependent creep, especially when the temperature is over 100 °C. This research provides important data for the safety assessment of sealing joints with PTFE gaskets.