An experimental study on the ratcheting and fatigue behavior of polyacetal under uniaxial cyclic loading and internal pressure

Ratcheting phenomena is one of failure modes. So study of ratcheting behavior and its effective parameters is essential to control it and improve fatigue life of structures components. To study some parameters of ratcheting strain and fatigue life of polyacetal, some experimental tests have been applied by using Instron servohydrolic machine under uniaxial loading and internal pressure. Effects of internal pressure is analyzed. Results showed by increasing cycles, softening occurred in material. Also result showed at initial cycles by increasing pressure, the ratcheting strain values increased. Increasing internal pressure ends to decreasing fatigue life.