Ying-Lei Lin

Finite element modeling of male leg and sportswear: contact pressure and clothing deformation

In clinical practice, fast assessment of contact pressure is usually calculated by Laplace’s Law, which neither provides detailed surface geometry for soft materials of the leg, nor offers sufficient predictive power for designing high-performance sportswear. To bridge this gap, this paper describes a finite element (FE) model of sports tights that was developed with a detailed anatomic male leg model to predict the compression effects of high-performance sportswear. Non-linear elastic material was applied on the sportswear material to model the large deformation behavior. Experimental validation on athletes was performed. A reasonable agreement was found in the experimental validation. Suitable profiles were achieved along the height of the leg, in terms of both contact pressure and clothing deformation (true strain or logarithmic strain). The maximum contact pressure (2222 Pa) occurred on the posterior of the ankle, while the maximum principal true strain of the sports tights occurred on the edge of the upper thigh. This study indicates that the proposed FE model is useful for the assessment of contact pressure distribution in sportswear.

Effects of fabrics with dynamic moisture transfer properties on skin temperature in females during exercise and recovery

Based on the physiological nature of breast movement in exercising females, a sports bra made of fabric with dynamic moisture transfer properties was developed to improve female thermal comfort. This study aimed to investigate the effects of fabrics with dynamic moisture transfer properties on breast skin temperature, and the thermal physiological and psychological response of women while wearing the sports bra during exercise and recovery. Ten healthy women exercised in random order with two types of sports bra with or without the dynamic moisture transfer properties and then performed a 20-minute short-duration high-intensity exercise and rest to recover under thermoneutral conditions. Heart rate, body core temperature, skin temperature, body mass and thermal psychological subjective sensations were investigated during exercise and recovery. The results indicated that in the running state, the local breast skin temperatures of sports bra made of fabrics with dynamic moisture transfer properties (33.427 ± 0.087℃) are significantly lower than bras without these dynamic moisture transfer properties (33.964 ± 0.055℃) (P < 0.01). During the exercise and recovery, the thermal psychological subjective sensation for the two types of fabrics were very similar, whereas the body mean skin temperature was revealed to undergo greater decreasing effects in sports bras made of fabrics with dynamic moisture transfer properties than those without the dynamic moisture transfer properties (P < 0.05). These results provide novel information that usage of fabrics with dynamic moisture properties in sports bras could improve thermoregulation to benefit exercising women’s thermal comfort in terms of decreasing local breast skin temperature.

An optimized design of compression sportswear fabric using numerical simulation and the response surface method

Well-designed compression sportswear can be used for the enhancement of athletic performance and reduction of injury. The material and geometric properties of fabric for compression sportswear are vital in achieving compression effects. This study evaluated and optimized the performance of fabric using the design of experiment (DOE) methods, the response surface method (RSM) and the finite element (FE) model. The evaluation and optimization procedure consisted of three phases. The first phase involved developing the FE model of a fabric tube and cylinder, and validated it by compression experiments involving different fabrics. The second phase evaluated the FE prediction using a five-factor experimental design, namely, hyperelastic properties, thickness, density, friction, and tensile strain. The third and final phase was an optimization process using RSM based on the evaluation results. Findings show that the FE predictions approach closely the results of validation experiments. The nonlinear elastic material properties (hyperelastic properties) and shape dimensions (thickness and tensile strain) of fabric tube were found to be important design factors in influencing contact pressure, while the density of fabric and interface friction coefficient played less important roles. The optimal FE model was determined using RSM analysis. The statistically based FE model was found to be an effective approach for evaluating and optimizing the design parameters of fabric for compression sportswear. The results can be applied to make sportswear that has different compression effects at selected anatomical locations to enhance performance and reduce injuries.