Mode I delamination of a constrained Double cantilever beam specimen

Delamination is a critical failure mode of composite laminates, which is typically investigated though fracture tests on standardized beam-like specimens, such as the Double Cantilever Beam. However, in-service components may experience delamination under constrained conditions that are not typically considered in standard fracture testing. Studies on two-dimensional delamination of central defects in composite laminates have highlighted that significant membrane stresses arise during delamination due to the geometrical constraints, and that their presence may affect the delamination behavior. The influence of membrane stresses on mode I delamination behavior has however not been systematically investigated. In this work, a novel Constrained Double Cantilever Beam (CDCB) specimen was developed and tested to investigate mode I delamination under constrained conditions. The results provide a first experimental assessment of the CDCB configuration, with emphasis on the evolution of in-plane stretching and its influence on crack propagation and specimen stiffness.