Crack Nucleation Prediction through Surface Roughness Measurement

Reusable life models rely on a large empirical database and require a lengthy development process. The models must be reconstructed for each new geometric and loading application. Rather than using empirical fatigue data to fit the model, the VEXTEC approach uses the intrinsic microstructure properties of the material and needs very little calibration testing. In Phase I, VEXTEC used the model to predict RUL for a flat plate specimen in a four point bending stress state to within 95% confidence of the test results. The simulated data were generated in less than 2 weeks. These RUL results show that the VEXTEC model can be universally and efficiently applied to new airframe components of the same material with high accuracy. The model was shown to use the particle density material property along with other properties measured from the material to predict the number of microcracks propagating through the microstructure of the material. The Phase II will create a comprehensive RUL prediction system by expanding the capability. Further refinement and added fidelity within the VEXTEC models will produce higher confidence RUL prediction results while maintaining the cost and speed advantages over current modeling systems.