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14:40   Sports apparel; modelling and simulation Chair: Tom Allen 14:40 20 mins INVESTIGATING FOOT-SOCK FRICTION: A COMPARISON OF TWO DIFFERENT METHODOLOGIE Matt Carre, Diyana Tasron, Roger Lewis, Farina Hashmi Abstract: Two different methodologies for assessing the friction between plantar skin and sock textiles are compared in this study. The first approach uses a custom-built friction plate rig. The rig consists of sock material mounted on a test plate attached to two load cells that measure normal and shear loads at the skin-sock textile interface. With this methodology, participants are required to slide their foot over the test plate whilst maintaining a targeted normal load and a relatively consistent sliding speed. The second approach uses a pneumatically-driven foot probe loading device. The device includes an instrumented probe with sock material on its contact surface. Participants are instructed to stand on a platform whilst the probe is applied to, and then driven across, the plantar aspect of foot. The cyclic motion of the probe is displacement-controlled and normal and shear loads are measured using load cells. Both approaches allow friction coefficients to be calculated from load data collected during the sliding phase of movement. Data from both approaches was examined, collected from friction tests using the same six participants and sliding contact between the first metatarsal head (1MTH) region and textiles from two commercially available running socks. Both approaches were capable of measuring the friction between 1MTH skin and sock materials and good agreement was found between them. In the dry conditions tested, the cotton-rich sock was found to provide lower friction that the anti-blister sock material. The first approach uses a custom-built friction rig that has been developed at the University of Sheffield. The rig consists of sock material mounted on a test plate attached to two load cells that measure normal load and friction force at the skin-sock textile interface. Measurements can be made in the range of 0.5 to 500N. With this methodology, participants are required to apply their foot against the test plate and maintain a targeted load whilst keeping a relatively consistent sliding speed. The second approach uses a pneumatically-driven foot loading device, developed at the University of Salford. The device includes an instrumented probe with sock material on its contact surface. Participants are instructed to stand on a platform whilst the probe is applied to, and then driven across, the plantar aspect of foot. The applied normal load is regulated by computer-controlled pneumatic valves. Normal and friction loads are measured using load cells. Both approaches allow friction coefficients to be calculated using the normal and friction load data. This study will examine data from trials using both methods, compare the efficacy of both approaches in providing understanding of foot-sock friction mechanisms and consider how the methods should be employed to generate measurements that can be used to assess the performance of running socks. 15:00 20 mins MUSCULOSKELETAL SIMULATION OF SPORTS MOTION CONSIDERING TENSION DISTRIBUTION IN A WHOLE BODY COMPRESSION GARMENT Motomu Nakashima, Takefumi Hosoya, Takatsugu Shimana Abstract: Compression garments are widely used in various sports activities. Since the cloths in a compression garment are sufficiently attached to the human body, it is possible for a compression garment to have particular mechanical functions by appropriately arranging the tension distribution in the garment. However, the effects of such garment on muscle activity have not been sufficiently investigated yet. Therefore, a method of musculoskeletal simulation for such problems were developed in the present study. In the developed musculoskeletal model, particular parts of cloths which had larger tension against stretch were modelled as virtual ligaments. In order to distribute the virtual ligaments, 697 points (294 and 403 for upper and lower halves of the body, respectively) were defined on the whole body in the musculoskeletal model. These points could be used as start, end and via points for the virtual ligaments. As an example of analysis, a running motion was analysed in the present study. The running motion was acquired from the experiment using motion capture system, and put into the simulation model. One simple pattern of tension distribution was examined by the simulation. From the simulation, it was confirmed that the muscle activity changed according to the tension of the garment. Therefore the developed simulation method will be useful for the design (the arrangement of the larger tension parts) of the whole body compression garments. 15:20 20 mins JOINT TORQUE CALCULATION OF COMPRESSION SPORTS SPATS USING ANISOTROPIC HYPERELASTIC MODEL Hitoshi Aoki, Takatsugu Shimana, Hiroki Sato, Ryuma Yabuki, Akihiro Matsuda Abstract: Introduction In this study, numerical design method for high-performance sports spats was proposed. Proposed design method was able to calculate stress distributions of sports spats during running motion. The joint torques given by the high-performance sports spats during running was also calculated to investigate engineering design key-points of sports spats. In the proposed methods, stress distributions of sports spats were calculated using an anisotropic hyperelastic material model and 3-dimensional computer graphics model of human athlete. The anisotropic hyperelastic material model represents the mechanical characteristics of sports spats fabrics which show anisotropic mechanical characteristics and the stress-softening. Effects of orientation angle of garments and initial stretch of sports spats on the knee joint torques were evaluated numerically. Methods Uniaxial cyclic tensile loading tests were conducted to obtain mechanical characteristics of the sports spats fabrics. From the results, the anisotropic hyperelastic model considering the stress-softening was proposed to reproduce mechanical characteristics of the sports spats fibers. The anisotropic hyperelastic model was introduced into the numerical simulation. The numerical simulations were conducted by using the skin strain which was calculated by 3-dimensional computer graphics of human athlete. Conclusion 3-dimensional stress calculation of sports spats were conducted to improve engineering design tool for sports equipment. The effect of sports spats on human body during running will be shown by proposed numerical simulations.