Fatigue testing is used to determine how many load cycles a material can sustain or the failure load level for a given number of cycles. The results of fatigue testing vary dramatically depending on the material. For example, most steels and aluminum alloys behave very differently under fatigue. Steel typically has a fatigue threshold which means that if it is tested at loads lower than the threshold, it will never break. Most aluminum alloys do not have a fatigue limit. Even under a small load, most aluminum alloys will fail after a sufficient number of cycles.
Plastics (polymers) are very sensitive to strain rate, the speed of testing. Testing plastics at a higher rate will lead to different results than testing them at a lower rate. Similarly, plastics are temperature sensitive; meaning that they behave very differently at high temperatures than at lower temperatures.
Fatigue testing is very common in the automotive, aerospace, military and orthopaedic industries. This type of mechanical testing can be performed using very simple sinusoidal load cycles or may simulate very complex service life load profiles.
DDL has several means to conduct fatigue testing including hydraulic and electromechanical. Custom test regimens and test fixtures are available to address varying industry needs. DDL’s engineers are happy to apply their technical expertise to help solve testing challenges and provide value-based solutions.
ASTM Test Standards for Fatigue Testing
- ASTM D623 - Rubber property-heat generation and flexing fatigue in compression
- ASTM F1612 - Standard Practice for Cyclic Fatigue Testing of Metallic Stemmed Hip Arthroplasty Femoral Components with Torsion
- ASTM F1717 - Standard Test Methods for Spinal Implant Constructs in a Vertebrectomy Model
- ASTM F1798 - Evaluating static and fatigue properties of interconnection mechanisms and subassemblies used in spinal arthrodesis implants.
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