I. Fernandez Villegas

A comparative evaluation between flat and traditional energy directors for ultrasonic welding of CF/PPS thermoplastic composites

Energy directors, responsible for local heat generation in ultrasonic welding, are neat resin protrusions traditionally moulded on the surfaces to be welded. This study evaluates an alternative energy directing solution for ultrasonic welding of thermoplastic composites based on the usage of a loose flat layer of neat resin at the welding interface, referred to as ‘flat energy director’. Analysis of dissipated power, displacement of the sonotrode, welding energy and time as well as weld strength compared to more traditional energy directing solutions showed that flat energy directors, which significantly simplify ultrasonic welding of thermoplastic composites, do not have any substantial negative impact in the welding process or the quality of the welded joints.

Zero-flow: a novel approach to continuous ultrasonic welding of CF/PPS thermoplastic composite plates

Abstract Continuous ultrasonic welding of plastic films, fabrics, and even thermoplastic composite prepreg tape is a common industrial practice. However, continuous ultrasonic welding of stiff thermoplastic composite plates is challenging due to squeeze flow of resin at the welding interface, and significant local deformation of the welding stack, that are generally needed to achieve strong welds. This paper presents a novel approach to continuous ultrasonic welding of thermoplastic composite plates based on zero-flow welding. The proposed technique can create strong welds before any squeeze flow takes place at the interface. It is enabled by the use of very thin flat energy directors, owing to simultaneous melting of both energy director and adherends’ matrix. The results prove the feasibility and indicate the potential for high-strength welds between thermoplastic composite plates at very high speed.