Nonlinear Model of Torsional Fracture in Adhesive Pipe Joints

Adhesively bonded pipe joints are extensively used in pipelines. In the present work, Cohesive Zone Model (CZM) based analytical solutions are derived for the bonded pipe joints under torsional loading. A general expression of interfacial fracture resistance for adhesive pipe joints is derived which is suitable for arbitrary type of nonlinear interfacial laws under torsional loading. It is found that, when the bond length of the pipe joint is sufficiently long, the torsion load capacity is indeed independent of the shape of cohesive laws and the bond length. It is interesting to note that the maximum torsion load capacity is achieved when the torsion stiffness of the pipe and coupler are identical. A good agreement with the previous finite element analysis (FEA) result indicates that the current model works well. This model deepens the understanding of the interfacial debonding problem of bonded joints under torsional loading. The fracture energy based formulas of the torsion load capacity derived in the present work can be directly used in the design of adhesively bonded pipe joints.