Modeling of Thermoplastic Welding

Abstract

Optimizing healing of welded thermoplastic material or matrix requires the understanding of physical mechanisms involved in welding processes, which are mainly surface rearrangement and surface approach, wetting of surfaces, macromolecular diffusion and even cocrystallization at interface of semi-crystalline polymers. Linear viscoelasticity (LVE) precisely reflects the distribution of relaxation times in a polymer and is therefore strongly correlated to the molecular structure, i.e. the molecular weight, molecular weight distribution and molecular architecture. Hence, LVE is a powerful tool, which provides fundamental insights about the link between dynamics and polymer structure. It is convenient to model the linear viscoelastic response of a polymer by rheological models. Continuous carbon fiber-reinforced tapes are used in the aircraft industry to build structural parts by welding them one to another to constitute the desired part. Among the different available welding techniques, ultrasonic welding is of particular interest because of its energy efficiency and rapidity.