Study Of Driver Restraint System And Injury Protection For Front Impact Of Coach

With the rapid development of motor coach industry, the safety for the coachdriver is paid more and more attention to. Due to the lack of mandatory safety rules inChina, there is less research on driver’s protection technology. Most of developmentand design about coach is limited to structure improvement and optimization ofrollover and frontal impact. In frontal collision, because of the large intrusiondeformation of instrument panel and steering column, the driver is more easily injuredthan occupants. Therefore the development safety technology for the bus driver ismore urgent.Except for structure, restraint system is one of the effective measures toprotecting the driver from serious injuries. Based on this, researches in the paper wereas follow.First of all, A finite element model of a12meter bus was developed by usinghypermesh. A simulation of the front impact of the bus was carried out in Ls-dyna andthe reliability of the bus was analyzed.Then, the front impact model for driver restraint system of the coach wasestablished via MADYMO dynamic code. This model includes coach drivercompartment, the driver seat, three-point safety belt, steering system. Theacceleration curve from simulation of the coach front impact was used as the inputload condition in MADYMO model of the bus driver restraint system. Dynamicresponse of the bus driver on different positions of belt anchor and buckle wereanalysed.Next, the knee airbag of bus driver was designed preliminarily. Including designof coverage area, shape, initial size of the knee airbag, the folding processes andmethod, airbag inflation process. Dynamic response of bus driver was calculatedwith and without knee airbag. By contrast, the protection effect of driver knee airbagwas verified.At last, an optimization was conducted aiming at lower extremity protection ofbus driver. Area coefficient for the exhaust openings of knee airbag, the mass flowrate of gas generator, the strap length of knee airbag, position installed on the kneebolsters, initiation moment of knee airbag, belt stiffness, locking time of retractor,pretension of shoulder belt pretensioner, and pretightening force of buckle pretensioner were selected as the objects of study. The analysis of main effect showsthat there are three key influence factors, including initiation moment of knee airbag,the mass flow rate of gas generator and area coefficient for the exhaust openings ofknee airbag. Above three parameters was selected for multi-optimum. Based onmulti-objective genetic algorithms HMGP, an optimization was conducted in terms ofthe three factors. After optimization, the injury risk of driver’s lower extremities isgreatly reduced. What’s more, the injury of head, chest is reduced to a certain extent.The research in this paper has certain reference value for the protection of thebus driver, and design of knee airbag and optimization method can be used freference.