Research on Interface Viscoelastic Mechanical Model Based on Modified Cohesive Zone and Generalized Maxwell Models

Composite pipes are critical components in marine oil and gas transportation, with the interface between the pipe body and the joint often representing the most vulnerable point of the structure. The failure of marine composite pipes is frequently caused by their sudden exposure to large and high loading rate. Therefore, investigating the viscoelastic constitutive and damage model of the interface is essential, providing insights into the ultimate load-bearing characteristics of composite pipes under different loading rates. This chapter presents an interfacial viscoelastic constitutive formulation based on the generalized Maxwell model, deriving the relationships between interfacial stress, strain, and loading rate. A modified cohesive zone model is also proposed, wherein the fracture toughness, stiffness, and critical traction adapt according to loading rate variations. Additionally, an interfacial mechanical model that incorporates both rate-dependent spring characteristics and the viscous dissipation of multiple Maxwell units is developed, overcoming inaccuracies in previous models when describing interfacial mechanics under extreme loading conditions. To facilitate application within finite element analysis, the model is discretized and implemented using a VUMAT subroutine. A double cantilever beam specimen model is constructed to simulate interfacial mechanical behavior under varied loading rates, validating the model’s accuracy through comparison with DCB experimental data.