A Guide to Cyclic Fatigue Testing of Tibial Tray Components in accordance with ASTM F1800 and ISO 14879
- ISO 14879
- ASTM F1800
- High Cycle Fatigue
Written by Toby LaneA summary of the common parameters in the standardsFatigue fracture of knee tibial trays has been one of the most commonly reported failure mechanisms of Total Knee Replacements (TKR). It is caused by loss of underlying bone support resulting from biological reactions, such as wear-induced osteolysis. Under these conditions, the tibial tray becomes mechanically unstable, and cyclic loading imparted by normal walking causes fatigue cracks, ultimately leading to catastrophic failure.
We recommend that you review ISO 14879-1 and ASTM F1800 to fully understand the full requirements.
TEST FIXTURETibial tray tests are carried out in force control with the peak force set to 10% of the maximum force the tray can withstand. 900N is a typical value, but depending on the material, the force used is often in excess of 2000N. The number of cycles is determined by the user, but a typical value is 10 million. 10 Hz is the prescribed frequency for this test (although higher frequencies can be used if evidence that test results match those obtained at 10Hz is provided). Tests are run until either the spacer thickness is reduced to 3 mm or fragments, the tibial tray fails, cracks are detected in the specimen following visual inspection or non-destructive inspection or finally, if the maximum number of cycles is reached.
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