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A motion based virtual reality training simulator for bobsled drivers
Published in Steve Haake, The Engineering of Sport, 2020
A typical sled, shown in Fig. 2, has four runners; two fixed in the rear, and two in the front whose steerable yaw rotation causes them to experience a lateral component of the ice friction force. Even though this is used to control sled heading and lateral position, bobsleds are relatively uncontrollable. Ullman and Cross (1979) have estimated that the lateral friction coefficient for a bobsled runner is only approximately 0.07.
A human body model based method for injury risk prediction considering occupant stature and posture
Published in International Journal of Crashworthiness, 2023
Saichao Yang, Qing Zhou, Bingbing Nie, Jisi Tang, Yasuo Yamamae, Tadasuke Katsuhara
A sled model representing vehicle interior was set up for this study (Figure 2). The model included seat, seatbelt, steering wheel, airbag, instrument panel, foot rest, pedal, wind shield, roof and floor. The airbag deployed 13 ms after the crash began. The vehicle crash test results (No. 9065) from the NHTSA database were selected to validate the sled model, which represents the same vehicle from the test. The LSTC’s 50th percentile hybrid-III dummy FE model was used in the simulations for validation. The dummy response between the test and the simulation was compared. The method of ISO/TS 18571 was used for a quantitative comparison between the model output and the experimental results, which included the dummy’s head acceleration, neck force, neck moment, chest acceleration, chest deflection, left and right femur force. The corridor scores of all the signals were between 0.57 and 0.80, while the ISO ratings of most signals were between 0.57 and 0.75. It indicated that the sled simulation model was capable of representing a real world vehicle frontal collision [30,31]. Meanwhile, the THUMS models have already been validated in several load cases [32].
Safety priorities for occupant protection in rear impacts
Published in Traffic Injury Prevention, 2023
The FMVSS 207 standard involves loading an untrimmed seat on a rigid bedplate. It would be appropriate to upgrade the test using a fully trimmed seat with some type of body form that has contours and weight of the seated occupant. Several quasi-static test methods have been used that ensure the weight of the occupant on the seat and the shape of the pelvis and torso during the rear loading. Burnett et al. (2022) reviewed the available quasistatic methods and provides background on the evaluation of seats with occupant loading. FRED was a reasonable test method (Viano et al. 2019b). Whatever test is required should involve loading the seatback to 70-75 deg rearward of vertical. Most of the current procedures provide strength data only from the design seatback angle to about 45-50 deg. Field accidents show crashes with large seatback rotation, so the energy management from 50-70 deg should be included in any required evaluation. Quasistatic testing is important during the development of a seat and provides the initial evaluation of a seat design and components for energy management and deformation modes. This sets the stage for sled and crash testing during the vehicle development.
Effect of active resisted 30 m sprints upon step and joint kinematics and muscle activity in experienced male and female sprinters
Published in Journal of Sports Sciences, 2021
Sprinting is an important ability which is use in many sports, such as soccer, football, rugby and athletics. Therefore, improving sprint performance is one important goal of training in these sports. Sprint training is primarily focused either on increasing power and strength, or on improving the sprinting technique by improving efficiency of certain movements. (Petrakos et al., 2016) A generally used training method for increasing sprint performance is resisted sprints, as described by reviews of Alcaraz et al. (2018) and Petrakos et al. (2016). In resisted sprints, an external load is most often used, such as weighted sled pulling. (Bachero-Mena & GonzaLez-Badillo, 2014; Cronin et al., 2008; Petrakos et al., 2016) However, with weighted sled sprinting the challenge is friction, inertia of the sled and passive resistance. Initially, an additional force is required to overcome the effects of friction between the sled and the track surface, the static friction. (Cronin et al., 2008; Van den Tillaar, 2018a) While, when the sled begins to move, the friction between the track surface and the sled represents the total friction and load that has to be pulled. As such, the resistance will become lower than at the start. Furthermore, when using different loaded sleds, differences in friction due to the interaction with the surface (Linthorne & Cooper, 2013) makes it difficult to compare different studies. (Van den Tillaar, 2018a)