运动内衣承托及其动态舒适性能的有限元分析

Objective Without the adequate support and protection, females' breasts would suffer from troubles such as ligament rupture and mastitis during physical activities. Wearing sports bra could limit the movement of breasts, thus reducing the pain or discomfort during exercises. In order to predict and evaluate the function and comfort of sports bra, as well as to reduce the process of product design and development for intimate apparel industry, a dynamic contact finite element (FE) modeling system for human body and sports bra was constructed to evaluate the performance of sports bra with different design features from the aspects of control level and contact pressure. Method The data of female chest was obtained by 3-D body scanner to obtain the geometric model of breasts, body torso and sports bra. The method of interference fit was adopted to simulate the pre-tension of the breasts and sports bra after wearing. The displacement of the torso obtained from the motion capture system was used as the boundary condition to drive the finite element model under the gravity field. The motion of the breasts after wearing sports bra was simulated by this FE model and a parametric study was also conducted for different material parameters of the sports bra. Results The simulated results from the constructed FE contact model between human body and sports bra was validated with the motion capture experiment in terms of the nipple displacement. The calculated relative average absolute error was 4. 13% (braless condition) and 5. 15% (wearing sports bra) which denoted the accuracy of the FE method. Based on the numerical model, a parametric study was conducted to investigate different fabric materials on the control performance and wearing comfort. A virtual sports bra (SPB2) with higher Young' s modulus, which was 5 times than the original tested sample SPB1, was introduced into the FE contact model. The maximum motion displacement of nipple when wearing SPB1 was 235.043 mm, while that was 228.861 mm for SPB2. The control effect of breast movement by SPB2 was increased by only 2.6% when comparing with SPB1. With regards to the contact pressure, it was revealed that in a static state, the shoulder strap has the highest contact pressure, followed by the lower under-band and the bottom of breasts (Tab. 3). It is mainly because the effects of gravity lead to the sagging of the breasts, thus the shoulder strap produces a corresponding force to support the breasts. The dynamic contact pressure extracted from different positions of human body showed that large fluctuations were detected at the bottom breasts for both SPB1 and SPB2, appearing periodically. The dynamic pressure in the position of shoulder straps, under-band and bottom breasts of SPB2 (0.30-1. 19 kPa) was all higher than SPB1 (1.56-4.65 kPa) (Fig.10), which was out the range of comfort pressure of human body (1.96-3.92 kPa). The results showed that although the higher Young's modulus of sports bra could strengthen the control performance slightly, the corresponding increase of contact pressure was higher than the comfortable clothing pressure range of the human body, which could easily cause the human body feel discomfort. Conclusion The breast displacement and the dynamic contact pressure between breasts and bra were evaluated quantitively by the proposed numerical simulation method. The supportive performance and wearing comfort by sports bra with different material properties were compared. This model can be utilized to investigate the complicated contact mechanism between the breasts and sports bra during physical activities, thus comprehensively guiding the fabric selection of sports bra from the perspective of functionality and comfort. The intimated apparel industry will be benefited by the proposed method in terms of optimizing the design for sports bra and shortening the development duration.