Fatigue life predictions using the strain-life method are used in the design of modern light weight vehicle, for the complex loading that occur with the structural durability tests that these vehicles undergo. The accuracy of these predictions is dependent upon the many factors; geometry, loads & materials etc. This paper details a new procedure to ensure the quality and accuracy of the material parameters for the fatigue life prediction software.
The material parameters for the solver are obtained by performing strain-controlled fatigue tests. The geometry of the coupons tested is determined by size and thickness of the material specimen that they are machined from and the loading regime in the test. Detailed data analyzed is conducted on these tests and the parameters that are used as input into the CAE strain-life fatigue prediction software are generated.
The issues associated with incorrect fatigue life predictions due to the loading varying thought each test, due to the cyclic stress hardening/softening characteristic of metal are discussed.
This new procedure should ensure that issues with the generation of the parameters from the test data, as well as issues with fatigue solver inputs are detected, as the predicted fatigue life’s will not correspond to the physical tests life’s if any issue are found.