Abstract
Studies have been reported so far with regard to estimation of the stress acted on damaged members in actual machines under a constant load condition using the X-ray fractgraphy technique. However, the load applied on actually used machines and structures are variable. There are many unknown items with regard to application of the X-ray fractgraphy under such variable condition, and no report has been seen so far about such application.
As a part of research to clarify the effect of the variable loading on the correlational expression of X-ray parameters and fracture mechanic parameters, we have examined the effect of the variable loading that the stress ratio and the maximum load vary once in the fatigue crack propagation process, then made it clear that the stress could be estimated with high precision by acquiring the information on the hardness just below the fracture.
