Analysis of Mode III Delamination Fracture Testing Using a Midplane Edge Crack Torsion Specimen Available to Purchase

A shear deformation theory is used to analyze the edge crack torsion (ECT) specimen for Mode III interlaminar fracture testing. The theory is based on an assumed displacement field and the principle of virtue work. Mode II interference due to bending-twist coupling in general symmetric laminates is identified. The effects of free-edge delamination on the torsional stiffness and total strain energy release rate of a family of symmetric laminates containing 0, 90, and ±45 layers are studied. Favorable layups for the Mode III interlaminar fracture toughness characterization are recommended. Effective procedures for the determination of minimum torsional stiffness to initiate Mode III delaminations are established.