Mixed mode fracture properties characterization for wood by Digital Images Correlation and Finite Element Method coupling

This paper seeks to characterize the mixed-mode energy release rate for orthotropic media subjected to a mixed-mode complex loading under service conditions. Experimental full-field information on Digital Image Correlation along with numerical modeling by the Finite Element Method have been considered as complementary approaches to determining fracture behavior in wood. An optimization technique allows calculating the kinematic state from Crack Relative Displacement Factor. A finite element analysis is performed in the local stress field characterization based on Stress Intensity Factor. This hybrid method has proven that the mixed-mode energy release rate uncoupling for fracture mode separation is achieved without taking into account local elastic mechanical properties; these properties can then be deduced by computing reduced elastic compliances from the additional information provided by Digital Image Correlation and Finite Element Method coupling. Such a hybrid method has been employed for cracked Douglas fir specimens undergoing complex loading in tension for various mixed-mode ratio values.