materials Review Advances in Ultrasonic Welding of Thermoplastic Composites: A Review Somen K. Bhudolia 1,2,* , Goram Gohel 1,2 , Kah Fai Leong 1,2 and Aminul Islam 3,* 1 School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50, Nanyang Avenue, Singapore 639798, Singapore;
[email protected] (G.G.);
[email protected] (K.F.L.) 2 Institute for Sports Research, Nanyang Technological University, 50, Nanyang Avenue, Singapore 639798, Singapore 3 Department of Mechanical Engineering, Technical University of Denmark, Produktionstorvet, Building 427A, 2800 Lyngby, Denmark * Correspondence:
[email protected] (S.K.B.);
[email protected] (A.I.); Tel.: +65-82305882 (S.K.B.); +45-45254896 (A.I.) Received: 12 February 2020; Accepted: 11 March 2020; Published: 12 March 2020 Abstract: The ultrasonic welding (UW) technique is an ultra-fast joining process, and it is used to join thermoplastic composite structures, and provides an excellent bonding strength. It is more cost-efficient as opposed to the conventional adhesive, mechanical and other joining methods. This review paper presents the detailed progress made by the scientific and research community to date in the direction of the UW of thermoplastic composites. The focus of this paper is to review the recent development of the ultrasonic welding technique for thermoplastic composites to thermoplastic composites, and to dissimilar materials. Different ultrasonic welding modes and their processing parameters, namely, weld time, weld pressure, amplitude, type of energy directors (EDs) affecting the welding quality and the advantages and disadvantages of UW over other bonding techniques, are summarized. The current state of the ultrasonic welding of thermoplastic composites and their future perspectives are also deliberated.