This research was commissioned and funded by The Welding Institute (TWI). The Welding Institute are a global research and development facility specialising in the joining of materials for industrial applications. The purpose of this research was to develop capability in textiles joining, particularly ultrasonic and laser welding technologies, which is relatively new to TWI.

The appointed researcher adopted a ‘multi-strategy’ (Cresswell 2009) approach to the research; encompassing methods that were both familiar and unfamiliar to those usually adopted by TWI employees and researchers, whom mostly come from engineering and scientific backgrounds. The research was primarily undertaken with the adoption of a ‘craft-design’ approach that uses material investigation to explore and uncover interesting leads for investigation, which was the familiar approach of the researcher coming from a background in textile design. Material studies were carried out inquisitively without the formation of a particular hypothesis and insights were discussed with industry to identify potential commercial and functional application opportunities. Following the identification of an interest in welding stretchy fabrics Speedo agreed to become the main industry partner for the research, providing materials, access to testing equipment and validation of commercial opportunities for material samples relative to their application.

The main hypothesis for the research Laser melted patterns can be used to control the elastic behaviour of stretchy textiles to have a targeted and variable compressive effect on the body developed through discussion with Speedo in response to material samples produced using transmission laser welding equipment. A predominant scientific approach was adopted during the second phase of the research to quantify and control this effect: to demonstrate repeatability and test it both on fabric and the body. Methods that were unfamiliar to the researcher prior to this research such as mechanical testing and microscopic analysis were employed. Selection of either a ‘craft design’ or ‘scientific’ approach was made pragmatically in response to the research as it developed. Through a retrospective analysis of applied methods throughout the research trajectory it has been possible to define this particular ‘multi-strategy’ project as a ‘sequential exploratory’ design (Cresswell 2009), whereby periods of subjective investigation are followed by empirical testing.

The main process that has been developed by this research is a decorative method of controlling the elastic behaviour of stretchy fabrics using transmission laser welding equipment for a controlled and variable compressive effect on the body. Compression fabrics are used widely within the medical, lingerie and sportswear fields to apply pressure to the body either for an aesthetic or functional advantage. In swimwear, compression fabrics are applied to streamline the silhouette and minimise drag resistance.

The technique developed by this research makes a contribution to knowledge within the field of laser processing of textiles, specifically within the field of transmission laser welding, and within the field of compression apparel. In the field of transmission laser welding a new functional capability for all-over surface patterns has been demonstrated. In the field of compression apparel a new decorative method for achieving an increasingly variable compressive effect for a smoother transition between different zones of stretch has been achieved.

N.B. All redacted information throughout this thesis is confidential to Speedo.