Analysis Of The Mechanical Properties Of Seat Belt Locking Device Based On The Magnetorheological Fluid

With the development of automobile industry, Safety performance of the automobile getting better and better, drivers have been better protected in the automobile accident. However, due to complexity of thoracic biological structural characteristics and limited living space for the driver in frontal impact, the driver chest protection is not very satisfactory. Focus on the factors in the driver’s chest injury and combined with the Chinese and foreign automobile safety regulations, in this paper, there is in-depth study on the driver’s chest stress in the automobile frontal crash. According to results of the study and the composite sensitive retractor locking mechanism, a new type of magnetorheological fluid locking device is designed, it achieved the purpose of better protection of the driver’s chest. The main contents of this paper are the following aspects. The literatures and regulations of Chinese and foreign are analyzed, chest force status and the thoracic biomechanical characteristics of the driver are summarized in the automobile frontal crash. It has analyzing in detail the injury mechanism, tolerability index, injury criteria and thoracic injury assessment standard, and then the mechanics index comply with the chest security is got. It has in-depth analyzing the operation principle of composite sensitive retractor locking mechanism, motion equations including car-sense, belt-sense and force bearing of the locking structure are built by Newtonian mechanics. Analytic solutions of the locking time and distance of the locking mechanism are determined used these equations. Three-dimensional models of the lock mechanism are established by CATIA, and the locking time of the three-dimensional models has been stimulated by using ADAMS.Based on the analysis of the Magnetorheological fluid, the flow model is built. A new type of magnetorheological fluid locking device is designed using this model. Based on the Bingham modle of the magnetorheological fluid, the damping force equation of the magnetorheological fluid locking device is solution out. The magnetorheological fluid locking device has been used in conjunction with the emergency locking seat belt. Based on the results of human thorax safety indicators and Magnetic saturation analysis method, mechanism and performance parameters of the MRF force limiters are established. Then, the three-dimensional models are established by CATIA. The relationship between damping force and the external current of the MRF locking device is established, and the current control equations are established using the MATLAB Fitting Toolbox. Based on the response time of the MRF locking device and passive safety features of the vehicle, different control scheme are developed out. The results show that the locking device can effectively reduce the compression amount and acceleration of chest. In other words, this MRF locking device can provide better protection for human body in the automobile frontal crash.