Abstract: A process for testing material samples comprises stressing samples under test by bending the samples with a bending fatigue system. During testing, an optical system takes images of the samples and cracks are identified in the samples using the images. Input variables and spatial variables for use in microstructure analysis of the images are determined and used to create a model. Based on the model, crack growth rates are predicted for untested microstructures based on the samples based on the analysis of the images.