Modern tennis has been played for over a hundred years, but despite significant improvements in the design and manufacture of tennis balls to produce a long-lasting and consistent product, the design of a tennis ball has barely changed in the last century. While some work has been done to better understand the dynamic behaviour of a tennis ball, no structured analysis has been reported assessing how the typical constructions of the inner rubber core and cloth panels affect its behaviour and performance. This research describes the development of an advanced and validated finite element (FE) tennis ball model which illustrates the effects of the viscoelastic and anisotropic materials of a tennis ball on ball deformation and bounce during impacts with the ground and the racket,representative of real play conditions. The non-linear strain rate properties exhibited by the materials of a tennis ball during high velocity impacts were characterised using a series of experiments including tensile and compressive tests as well as low and high velocity impact tests. The impacts were recorded using a high speed video (HSV) camera to determine deformation, impact time, coefficient of restitution (COR) and spin rate. The ball material properties were tuned to match the HSV results, and the ball s model parameters were in good agreement with experimental data for both normal and oblique impacts at velocities up to 50 m/s and 35 m/s, respectively. A time sequenced comparison of HSV ball motion and FE model confirmed the accuracy of the model, and showed significant improvement on previous models. Although the existing construction of tennis ball cores was found to provide a sufficiently uniform internal structure to base competition standard tennis balls, the anisotropic nature of the cloth panels resulted in deviation angles as high as 1.5 degrees in ball bounce. Therefore, new cloth panel configurations were modelled which allowed the cloth fibre orientations around the ball to be adjusted resulting in better bounce consistency. The effect of cloth seam length on ball flight was explored through wind tunnel tests performed on solid balls made by additive manufacturing (AM) and on actual pressurised tennis ball prototypes. A reverse Magnus effect was observed on the AM balls, however, this phenomenon was overcome by the rough nature of the cloth cover on the real tennis ball prototypes. A ball trajectory simulation showed that there was no obvious dependence between seam length and shot length or ball velocity. Finally, a basic panel flattening method was used to determine the 2Dsize of the cloth panel patterns corresponding to the new configurations, and tiling methods were designed to estimate cloth wastage. The traditional dumbbell design appeared to result in the minimum amount of waste. The work reported in this thesis represents a significant improvement in the modelling of tennis ball core, cloth and seams, as well as the ball s interaction with the ground and racket strings. While this research focused on woven cloth, needle cloth is also widely used in the manufacture of balls in the US. The modelling of needle cloth could therefore be part of a future study. Additionally, details such as the depth and roughness of the cloth seam could be included in the model to study their effect on spin generation. Also, including cloth anisotropy in the flattening method would allow a better prediction of cloth wastage which could then have an influence on the configuration of the cloth panels.

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The aim of this research is, “to investigate how the sports design process can be used to improve inclusive design practice”. Sports design (or sports engineering) is the design of sports equipment and/or products that support the athlete (or user) in improving their overall sporting performance (Jenkins, et al., 2010) and (Muller, et al., 2007). In sport, the equipment and the athlete must work together to facilitate sporting performance. Despite limited work being undertaken into the sports design process, sports design is evidently highly user centred. However, there is no design process model that captures the characteristics of sports design as a whole (from project initiation to project sign-off).This research captures the sports design process as a whole, using an iterative process of investigation, data collection, development, evaluation and validation, involving industry designers and sports design students. The outcome and contribution to knowledge is the first design process model to capture the sports design process as a whole. The characteristics of sports design captured in the model include user involvement throughout the design process, designer interaction with the user and iterations within design process stages. To address the overall aim of the research, this thesis investigates whether the user centred nature of sports design is applicable in other design disciplines. Given the urgent global issue of the ageing population, this research explores the applicability of the sports design process model to inclusive design – another highly user centred design approach. This research takes a qualitative approach to understanding how the sports design process model could be applicable to inclusive design practice, involving both inclusive designers from industry and inclusive design experts from the Helen Hamlyn Centre for Design. An iterative approach of concept generation, development and evaluation was followed, with the outcome and further contribution to knowledge, an interactive framework that facilitates designer-client communication within the inclusive design process. This research will impact client engagement within the inclusive design process, increasing client awareness of inclusive design and encouraging the uptake of an inclusive design approach within industry. The inclusion of a diversity of users within the design process will result in a product that not only meets the needs of more diverse users, but will also be usable to those with greater capabilities.

During the design of sports equipment, the main focus is usually on physical performance attributes, neglecting key subjective factors such as feel and comfort. The personal protective equipment worn in sport is a typical example, where injury prevention has taken precedence over user comfort, but it is anticipated that with a new approach to the design process, comfort can be improved without sacrificing protection. Using cricket leg guards and taekwondo chest guards as an example, this study aimed to develop a systematic method for assessing user perceptions and incorporating them into the design process. Players perceptions of the factors that influence the comfort of cricket leg guards and taekwondo chest guards were elicited through the use of co-discovery sessions, focus groups and individual interviews, and analysed through an inductive process to produce a comfort model. The relative importance of each different comfort dimension was identified through the use of an online questionnaire utilising the analytical hierarchy process method. Through the combination of these methods, six general dimensions were identified with a weighting regarding the amount to which each one determines a user's perceived comfort. For both cricket and taekwondo, the majority of players ranked Fit as the most important factor affecting comfort. Experimental procedures were developed to objectively test the Fit of cricket leg guards, with regards to batting kinematics, running performance and contact pressure. These methods were combined with subjective assessments of leg guard performance, to determine if there was a relationship between users perceived comfort and objective test results. It was found that shot ROM and performance were not significantly affected by cricket leg guards, despite perceptions of increased restriction whilst wearing certain pads. Wearing cricket leg guards was found to significantly decrease running performance when compared to running without pads (p<0.05). In addition, it was found that the degree of impedance depended on pad design and could not solely be attributed to additional mass. These results correlated with the subjective assessment of three different leg guards, with respondents identifying the pad which had the largest influence on their running biomechanics and impeded their performance the most, as the most restrictive pad. Contact pressure under the pad and straps was also measured for four different leg guards whilst running. The results found that the top strap applied the greatest amount of pressure to the leg, especially at the point of maximum knee flexion. The peak pressure under the top strap was found to reach up to three times that of any other area of the pad. These results were reflected in the subjective assessment of the leg guards, with all nine subjects identifying the top strap as an area of discomfort for certain pads. The results also suggested there was a preference for pads with a larger more consistent contact area, as pad movement was perceived to increase when contact area variation was greater. Finally the results from this research were used to develop a product design specification (PDS) for a cricket leg guard, specifying size, mass, contact pressure and shape. The PDS was used to develop a concept design which would maximise comfort, whilst maintaining protection.