Research On The Protective Effect Of Pretensioning Seatbelts For Occupant

In the traffic accident, the car seatbelt system is one of the most important occupant protection device. In order to ensure the occupant comfort, there is always a slack of the seatbelt in normal wear, it will reduce the protective effect of occupant restraint system. Pretensioners can effectively eliminate the webbing slack, which is widely used in retractor pretensioning, buckle pretensioning and other types. As the technology innovation, the two-stage pretensioners are used by car companies gradually, some literatures indicate that compared with the traditional unilateral seatbelt, two-stage pretensioning devices can improve the efficiency of the constraint of the occupant, and play an important role in reducing the risk of occupant submarining and improving thigh injuries.Based on the above reasons, this paper proposed a new bilateral pretensioning device on the basis of a single pretensioning device, and it can realize the function of the two-stage pretensioning device. Further, this paper launched the comparative study by the computer simulation based on the bilateral pretensioning, retractor pretensioning, and buckle pretensioning, to evaluate the performance characteristics of these three pretensioning device. The concrete research content is as follows:1. A new bilateral pretensioning structure was Proposed and by using CATIA the conceptual design was finished. By using MADYMO an occupant restraint system model was established and verified, on the basis of which the paper established the seatbelts models of the bilateral pretensioning, retractor pretensioning, and buckle pretensioning, and compared performance parameters, the occupant RIDE-DOWN energy efficiency and injury responses of the three kinds of pretensioning device under a typical working condition of collision among them.2. Based on the three kinds of pretensioners the orthogonal test designs were finished for webbing stiffness, pretensioning firing time, seatbelt hanging point height, and position lap belts four parameters, and an extreme difference analysis method was used to contrast the effects of the four parameters for occupant protection effectiveness under the action of the three kinds of pretensioner seatbelts.3. The restraint system model based on a MADYMO active human body was established, and under normal condition and dangerous conditions respectively, the comparative study of occupant abdominal injuries under the action of three different pretensioners was carried.Results show that the constraint efficiency of retractor pretensioning is limited by the magnitude of prestressing force, and the pretensioning force of bilateral pretensioning device and buckles pretensioning device can be increase to improve the webbing retraction travel, the pretensioning efficiency and RIDE-DOWN energy efficiency, it also is helpful to improve the thigh injury. Buckle pretensioning device can significantly reduce the amount of chest compression, and the overall protection effect of the bilateral pretensioning device is the best, buckle pre-tightening device secondly, furl pre-tightening is the worst.In addition, for different pretensioning belts, the optimal level of influence factors of occupant protective effect is different, then the results can provide a valuable reference for parameters optimized matching of different kinds of pretensioning seatbelts.Under the normal working condition the pretensioning type has a very small effect on occupant abdominal injuries, and correctly wearing your seat belt and good matching of retraint system can improve the risk of abdominal injury; Under dangerous working conditions bilateral pretensioning seatbelt can reduce the risk of occupant diving, has a better protective effect relative to the other two pretensioners, in addition, compared with retractor pretensioning, occupant abdominal injury under the action of buckle pretensioning seatbelts is smaller.The research results of this paper had certain guiding significance on improving the existing way of pretensioning and the development of new pretensioners.