Investigation of Alignment Methods and Its Effect on Mechanical Performance of Discontinuous Tow-based Composites: An experimental design study

Composites are used in applications where the combination of low density and high stiffness is wanted, as can be frequently found in the aerospace industry. Within the composites family, discontinuous fiber composites (DFC) started to gain interest in the aerospace and automotive industry, due to their potential for high production rates. In...

Thermal effects on the performance of ultrasonically welded CF/PPS joints and its correlation to the degree of crystallinity at the weldline

The effect of temperature on the lap shear strength (LSS) and failure mechanisms of ultrasonically welded carbon fibre reinforced polyphenylene sulphide (CF/PPS) joints was investigated, correlating the weld performance to the crystallinity degree of PPS at the weldline. The single-lap shear tests were carried out at temperatures ranging from...

Multi-spot ultrasonic welding of thermoplastic composite single-lap joints: Effect of spot spacing and number of spots on weld strength

Thermoplastic composite spot welded joints are more well-suited for carrying shear load rather than peel load. However, peel load is difficult to be eliminated in single-lap joint configuration. In this paper, a series of mechanical tests were carried out to study the effects of the spot spacing and the number of welded spots on the secondary...

Effect of resin-rich bond line thickness and fibre migration on the toughness of unidirectional Carbon/PEEK joints

It is a common practice in fusion bonding of thermoplastic composites to add a matrix layer between the two substrates to be joined. The aim is to ensure proper wetting of the two parts. The effect of this additional matrix layer on the mechanical performance was studied by mode I fracture toughness measurements. The additional matrix was...

Sequential ultrasonic spot welding of thermoplastic composites: An experimental study on the welding process and the mechanical behaviour of (multi-)spot welded joints

The popularity of thermoplastic composites (TPCs) has been growing steadily in the last decades in the aircraft industry. This is not only because of their excellent material properties, but also owing to their fast and cost-effective manufacturing process. Fusion bonding, or welding, is a typical joining method for TPCs due to the intrinsic...

Interlaminar fracture toughness of 5HS Carbon/PEEK laminates. A comparison between DCB, ELS and mandrel peel tests

The present work focuses on the applicability of the mandrel peel test to quantify the interlaminar fracture toughness of 5 harness satin woven fabric Carbon/PEEK composites. For this purpose, the Mandrel Peel (MP) test was compared to the Double Cantilever Beam (DCB) and End-Loaded Split (ELS) test in terms of experimental procedure and...

On the effect of flat energy directors thickness on heat generation during ultrasonic welding of thermoplastic composites

This paper presents a detailed experimental assessment of the effect of the thickness of flat energy directors (ED) on heat generation at the interface during ultrasonic welding. Power and displacement data showed clear differences caused by the change of thickness, related to heat concentration at the weld line during the process. The extent...

Towards high-quality multi-spot-welded joints in thermoplastic composite structures

Ultrasonic welding is a promising assembly technique for thermoplastic composites and it is well-suited for spot welding. In this study, two typical welding process control strategies, i.e. displacement-controlled and energy-controlled welding, were selected to manufacture spot-welded joints. The influence of different boundary conditions,...

Comparative analysis of in-plane and out-of-plane mechanical behaviour of spot-welded and mechaincally fastened joints in thermoplastic composites

Ultrasonic welding is a promising assembly technique for thermoplastic composites and it is well-suited for spot welding. In this paper, the in-plane and out-of-plane mechanical behaviour of ultrasonically spot-welded and mechanically fastened joints are investigated by double-lap shear and pull-through tests, respectively. Special attention was...