Strain distribution and rearrangement in a cracked and uncracked composite laminate

Forces that are applied to structures made from advanced composites generate complex strain distributions at the micro and mesolength scales. Furthermore, these strain fields evolve as damage accumulates static and dynamic conditions. Many studies have attempted to model or approximate deformation in advanced composites by accounting for the geometry and material properties of the components of the composite material system. However, such models have rarely been experimentally verified and are often unable to reliably predict failure because the details of the strain distributions at appropriate length scales are not known. This paper presents an application of digital image correlation to make real time, in-situ, strain measurements of distributions in a structural composite. These measurements show the evolution of deformation in composite architectures up to the point of matrix cracking, and capture the redistribution of strain following these initial failures. This technique can be utilized to identify architectural features associated with crack formation and their relationship to statistical measures of the microstructures.