Bumper lightweight design (2)

Lightweight materials
1. Aluminum
The density of aluminum is only 1/3 of that of steel, and it is a material frequently used in automobile bumpers designed to reduce weight. The front bumper of the Audi 100C3 sedan is composed of an outer plate made of plastic and a beam made of aluminum alloy. The material of the beam is A1MgSMnW27 and the plate thickness is 2.0mm. The main purpose of using aluminum alloy as the front bumper beam is to reduce the mass, and secondly, to use its characteristics of absorbing collision energy.
2. Aluminum foam
The car bumper made of foamed metal aluminum material can absorb the collision energy of the two cars to a large extent, which greatly improves the safety of the car. In terms of performance, the aluminum foam-filled round tube has a very excellent impact energy absorption effect during axial impact, so it has a very broad application prospect in mechanical buffer devices.
Compared with the traditional thin-walled hollow metal bumper, when the energy absorption is the same, the wall thickness of the tube, the inner radius of the tube and the length of the tube are the same, the foam aluminum filled round tube car bumper only needs 11 foam aluminum filled round tubes. , And the hollow metal round tube bumper needs 20 hollow metal round tubes. The energy absorbed by a foam aluminum filled round tube is 82% higher than that of a hollow metal round tube. Therefore, the foam aluminum filled round tube automobile The mass of the bumper is 55% less than that of the hollow metal tube bumper. Automotive special materials, functional masterbatch technology seminars and new product promotion.
3. Nitinol
Nitinol is a new type of material with special properties that other materials do not have, such as shape memory characteristics and pseudo-elasticity. It is currently used in the inner and outer panels of some automobile bumpers. Titanium is a typical light metal, and the overall density of nickel-titanium alloy is much lower than that of traditional steel, so it has higher specific strength and specific stiffness. The huge restoring force due to the shape memory properties also further improves the overall performance of the material.
4. Polypropylene (PP)
Polypropylene (PP) plastic has the characteristics of light weight, abundant raw material sources, superior performance-to-price ratio, excellent heat resistance, chemical resistance, easy molding, and easy recycling. Therefore, it is widely used in automobile bumpers. However, PP also has the defects of low impact resistance, poor aging resistance and poor dimensional stability, and it is difficult to meet the requirements of the balance of bending strength and impact strength of automobile parts.
Therefore, most of the PP materials used in automobile parts are modified PP, namely PP alloy materials [5]. Rubber polymers commonly used to modify polypropylene include butadiene rubber (BR), ethylene propylene rubber (EPR), ethylene propylene diene rubber (EPDM), SBS, POE, etc. BR, EPR, EPDM are equal to PP blending modification, which can greatly improve its impact strength, especially EPDM and PP have similar structures, similar solubility parameters, and good compatibility. Therefore, the use of EPDM to toughen and modify PP is the most widely used. The improvement in impact performance is also very significant.
The car bumper made of PP/EPDM has high rigidity, good impact performance, damage resistance, good gloss and elasticity, and easy painting. It is not easy to break when the car is impacted at high speed, and the decoration is beautiful.
5.PC/PBT alloy
The materials made of PC/PBT alloy not only have good mechanical properties, but also have much higher impact strength than modified PP elastomers, and are easy to weld and paint. For example, the PBT/PC alloy of GE in the United States, XenoyXT is especially suitable for automobile bumpers. The rear bumpers of DaimlerChrysler's Town, Country and Caravan cars use this kind of plastic alloy. There are currently several large companies in the world that produce engineering plastics.
6. Thermoplastic elastomer TPE (ThermoPlasticElastomer)
At present, the use of TPE in the world bumper market has occupied 53% of the share. Because modified PP or PC/PBT alloy is not conducive to recycling, some foreign automobile companies use a single thermoplastic elastomer (TPE) to manufacture car bumper panels, while glass fiber reinforced PP is used to make skeleton materials. Materials of the same family are conducive to recycling.
TPE can be processed with thermoplastic processing equipment, but its properties show the same elasticity as rubber, so some people call it the third-generation rubber material.
The TPE material has low density, is easy to recycle, and its performance is between plastic and rubber. At present, there are mainly four types commonly used in automobiles: thermoplastic polyolefin elastomer (TPO), thermoplastic polystyrene elastomer (TPS), polyester elastomer (TPEE) and polyurethane elastomer (TPU), among them there are A little difference, suitable for different occasions.

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