CYCLIC COMPRESSIVE LOADING RESULTS IN FATIGUE CRACKS IN ULTRA-HIGH-MOLECULAR-WEIGHT POLYETHYLENE

Wear damage to the articulating surfaces of total joint components mad e of ultra high molecular weight polyethylene is associated with a fat igue fracture mechanism, despite the fact that these surfaces are subj ected to primarily compressive and compressive-tensile cyclic stresses . The question arises as to whether fatigue cracks will form under suc h loading conditions. In this study, we experimentally demonstrated th at fatigue cracks could be initiated and propagated in notched ultra h igh molecular weight polyethylene specimens subjected to fully compres sive and compressive-tensile cyclic loading. Under these loading condi tions, growth of fatigue cracks was limited: the cracks arrested witho ut catastrophic failure of the test specimens. The final length of the crack was dependent on the load ratio of the fatigue cycle; fatigue c racks propagated to greater lengths as the load ratio was increased.