| Till now, the global automotive industry is almost one of the biggest and most complicated fields in industrial history. While with the sharp increasing quantity of automobiles, the traffic accidents old as cars themselves increased accordingly. At present, the injuries of traffic accidents account for about a quarter of worldwide injuries and deaths. On the one hand, worldwide governments as policymakers are doing their best efforts to specify the safety standard of vehicles. On the other side, car manufacturers are also focusing their efforts on the quality of safety especially their crashworthiness and crash compatibility. Lots of products including bumper, seat belt, airbag, anti-locked braking system (ABS) improve the safety of drivers when suddenly stopping and crashing happen. Except safety, pollution is one big serious problem. The vehicles bring lots of poisonous gas such as NOx and CO2which was one major cause of global warm. With the urgent needs for saving energy and protecting environment, economic cooperation (ECO) vehicles are becoming more and more desirable. It is a good way to improve the fuel efficiency through reducing the weight of cars. However, for traditional mental materials, it is hard to achieve high energy absorption properties with light weight. Therefore, new material system was considered to substitute traditional metal materials to manufacture next generation vehicles. In this field, fiber reinforced plastic composites (CFRPs) attracted attentions specially.Fiber reinforced plastic composites with light weight did not exhibit the ductile failure mechanism which was related to metals. FRPs absorb lots of energy through progressive crushing mode by a combination of multi micro-crack, bending, delamination and friction. FRPs with half weight of traditional metals while absorb more than doubled energy. But FRPs were not used as energy absorption components in wide-range, one of the most important reasons is their high manufacturing cost. In this study, complementary reinforced fibers (carbon and aramid fibers) were chosen to manufacture composites. By optimizing different hybrid method, ratio and reasonable geometry shape of composites, low cost and high energy absorption components whose specific energy absorption (Es) were up to100kJ/kg could be manufactured to put to use on vehicles. In detail, carbon fiber and aramid fiber were chosen as reinforcements and common epoxy resin was chosen as matrix to manufacture five types of different structures and raw materials of carbon/aramid and carbon/carbon fiber reinforced plastic composite tubes through high productive and low cost winding method. Then specimens were dealt under100and200℃condition for100hours,200hours and400hours treatment respectively. After that, energy absorption ability was tested by quasi static compression test and microscope observation of cross section was taken to analyze the mechanism of failure after cutting, curing, polishing and so on.It was found that the energy absorption ability of carbon/aramid fiber reinforced plastic composites increased after treatment under100℃for100hours,200hours compared to composites without treatment, and energy absorption ability improved with the treatment time increased. But for carbon/carbon fiber reinforced plastic composites, there is no obvious effect on the energy absorption ability after treatment. Three layers (aramid/carbon/aramid) structure exhibited more excellent energy absorption capability than five layers (aramid/carbon/aramid/carbon/aramid) structure of carbon/aramid FRPs even with same fiber content and orientation. Both are three layers structure, carbon/carbon FRPs (carbon/carbon/carbon) showed better performance on energy absorption than carbon/aramid FRPs (aramid/carbon/aramid) composites without tempertature treatment, but carbon/aramid FRPs composites with temperature treatment could achieve more excellent capability of energy absorption than carbon/carbon FRPs composites.Meanwhile, according to microscope observation of cross section of carbon/aramid and carbon/carbon FRPs, failure modes were divided into three modes including bending mode, splaying mode and buckling mode, which sorted from highest to lowest in the aspect of energy absorption. But in common, failure mode of FRPs is not only one single failure mode but a combination of several failure modes, and the failure mode has close relationship with the length of central crack. Under the premise of avoiding buckling deformation, best efforts should be made to control the propagation of central crack for making the fronds bend to inner side and outer side with small curving curvature, in this case, fibers in bending fronds could break (one of the most important ways to absorb energy) as far as possible.Composite tube with specific energy absorption95.67kJ/kg (aramid fiber88°/carbon fiber17.6°/aramid fiber88°:1/13.3/3.3,200hours temperature treatment under100℃) was manufactured successfully in this study. It mainly reached the goal of fabricating high performance and low cost composites which could be used on vehicles. |
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