Optimization of the comfort of compression sports bras

Abstract

Sports bra is an undergarment for women designed to provide extra support, control breast movement and provide protection to the breasts during exercises. Comfortable and functional sports bras are the strong needs and essentials for women, especially for physically active women. However, there is limited literature to develop efficient, valid and reliable computer-aided method to simulate the contact conditions between females and sports bras; and there is limited literature to combine numerical simulation and comfort pressure evaluation to determine an optimal material parameter of sports bra fabrics. Systematic studies on this area are needed to provide design considerations for intimate apparel industry and arouse attention to women's health. Therefore, the key aim of this study was to establish and validate a new scientific method to combine finite element (FE) modelling and subjective perception of comfort pressure to determine the optimum pressure and fabric parameters for the comfort of sports bras. The specific objectives were to build appropriate FE models of female bodies and sports bras to simulate pressure distribution on body exerted by a sports bra, and to determine the range of comfort pressure wearing a sports bra, then to identify the optimum material parameter of sports bra fabrics for optimum pressure comfort. This study consists of four parts to achieve these objectives. The first one is building an accurate FE model of female body, which has a rigid torso, hyperelastic breasts, and subcutaneous tissues. The coefficients of the Mooney-Rivlin material, which describe the female breasts, are determined by examining the differences between the FE-modelled results and experimental data. The second is developing the FE contact model of a female body and sports bra to calculate the static and dynamic contact pressure and dynamic displacement of the breasts. The contact model is developed by a new method called 'first shrink then expand' and validated by motion capturing experiment. The calculated root mean square errors are less than 1%, which shows a good agreement between the FE results and experimental data. The third is determining comfort pressure range by subjective questionnaire about comfortable sensation and objective pressure tests. The pressure feelings are analysed not only in static condition (standing or sitting) but also in dynamic condition (running). The optimum contact pressures on the shoulders, underarm and at the bottom of the bra cup are 2.08 ± 0.82 kPa, 2.66 ± 0.83 kPa and 0.58 ± 0.57 kPa respectively based on the results of Chapter 5. The fourth objective is making prediction of contact conditions using finite element (FE) and machine learning (ML) approaches. FE results are used to provide the database for the ML model. A comparison between the results obtained from the FE and ML methods shows a good agreement between the two methods. The effect of different sports bra components on the contact pressures is investigated through the results of ML model, which is that the shoulder strap and bra cup can greatly influence the contact pressure, while the back panel and elastic bra band do not have much influence the contact pressure. This study provides a robust computational method to optimize the design of sports bras. This method can also potentially be applied to solve the contact problem between relatively rigid and hyperelastic materials, or other problems in the area of comfort, elastic materials, intimate apparel and sports activities. The optimization of sports bra can address a common need and contribute to the wellbeing of women globally.