Rakish Shrestha¹, Jutima Simsiriwong², Nima Shamsaei¹; ¹Auburn University, ²University of North Florida

Engineering thermoplastics are being extensively used in aerospace, automotive, and bio-medical industries as a lightweight alternative for manufacturing structural components that are subjected to cyclic loading. As a result, the understanding of fatigue behavior of polymeric materials, especially under various realistic cyclic loading conditions, need to be fully obtained. In this study, the fatigue resistance of polyether ether ketone (PEEK), an engineering thermoplastic, is investigated under various strain-controlled loading conditions. These include (I) uniaxial fatigue tests with and without mean strains, (II) uniaxial fatigue tests with variable amplitude loadings, and (III) multiaxial fatigue tests. Deformation behavior for PEEK polymer under different loading conditions is discussed using both macroscopic and microscopic analyses. A damage parameter capable of correlating the fatigue life obtained from various loading conditions is also proposed.