Double Cantilever Beam Delamination: Cohesive-Zone Model (2D)

This 2D companion to the flagship 3D double-cantilever-beam (DCB) delamination test resolves the same Mode I interlaminar fracture problem with a genuinely different numerical method. Instead of assuming the bondline is perfectly rigid until an analytic energy-release-rate criterion says it should fail outright, this model discretizes the bondline into dozens of stations, gives each one a real bilinear cohesive traction–separation law calibrated to the ply system's own fracture toughness, and solves the beam's exact governing equation directly every frame as the crosshead opens the specimen. The crack length is not solved for — it emerges from where local interfacial damage has run to completion — and a moving process zone of partially-damaged bondline is visible ahead of the fully-open crack, a feature that a closed-form LEFM solution cannot show. Pick a ply system, tune the initial flaw, arm thickness and opening rate, and watch the interfacial damage front advance, station by station, exactly as it does inside a real cohesive-zone finite-element model.