In den letzten Jahren haben sich mit der rasanten Entwicklung der Automobilindustrie die unterschiedlichen Anforderungen der Menschen an Autositze weiter verbessert. Leichtgewicht, Multifunktionalität, Umweltschutz, Komfort und Sicherheit von Autositzen sind die Grundbedürfnisse der Menschen an Autositzen, daher haben diese Aspekte zugenommen werden nach und nach zur Hauptrichtung der Entwicklung von Autositzen. Langfaserverbundwerkstoff besteht aus Harz und Langfaserverbundwerkstoff mit einer Vielzahl von Eigenschaften, wie hoher Festigkeit, geringer Dichte, kurzer Produktionszeit und einfacher Formbarkeit, geeignet für den aktuellen Entwicklungstrend von Autositzen, also im Automobil Industrie hat es sich nach und nach zur ersten Wahl für Autositzmaterialien entwickelt.

1. Übersicht Autositze

Car seats are mainly composed of four parts: seat cover, seat pillow, seat foam and seat skeleton. In addition, due to different market demands, some seats also have armrests, waist brackets or massage and other related comfort components, and some seats have cuphorers, drawers and other storage functions.
At present, the lightness, comfort and safety of car seat design are of great significance. However, most of the main materials of conventional seats are metal materials, which have high density and heavy weight. Therefore, the development space of improving the lightweight of car seats only by optimizing the structure and design is limited. Long fiber reinforced composite materials have excellent mechanical properties and can achieve significant lightweight effect. Therefore, they are gradually applied in the automotive field, not only in most simple non-important parts, but also in some complex shape functional parts, such as the seat frame and the front segment module.

2. The importance of automobile lightweight

Automobile lightweight means that on the basis of the safety performance and strength of the automobile can be guaranteed, the overall weight of the automobile can be reduced to the maximum extent, so as to enhance the power of the automobile, and reduce emissions and fuel consumption. According to the relevant tests, the fuel quantity of the vehicle has the most direct relationship with the weight of the vehicle quilt itself. The fuel consumption of 100 kilometers can be reduced by 0. 2 and 0. 8 L for every 1 kg weight reduction of the vehicle, which is usually about 4. 5% of the original consumption. Therefore, under the background of environmental protection and energy saving in automobile development, the lightweight of automobile is of great significance in the design and manufacturing process of modern automobile.
Car seat is one of the most important interior parts in automobile. According to the survey, the weight of the car seat in the entire body accounts for 15% of the proportion. Although the car seat occupies a small proportion in the total weight of the body, however, as one of the large and extremely important parts of the car interior, its contribution to the lightweight process of the whole car can not be underestimated. Car seat is one of the more complicated parts in the whole process of car design. The design process of the car seat must be considered from many aspects, such as safety, the beauty of the shape, functional diversity and comfort, must be established in line with the requirements of the traditional car seat under the premise, can implement the lightweight design of the car seat, reduce the weight of the car seat at the same time, the basic performance of the car seat must be guaranteed, especially the safety of the seat. Under the influence of these requirements, the lightweight design of car seat becomes more challenging and more worthy of people's research.

3. Application status of long fiber composites in automotive field

With the rapid development of industrial economy, long fiber composite materials have also been developing rapidly. At present, long fiber composite materials have become one of the fastest growing industries in the reinforced plastics industry. In Europe and the United States and other developed countries, long fiber composite materials have been greatly developed, such as the Japanese Emperor Company, LNP Company, Ticona company, Saint-Gobain Company and other internationally well-known material enterprises have developed long fiber composite materials.
The application proportion of home automobile field is large, accounting for about 33% of the total consumption, and will continue to grow with the development of the automobile industry. At present, long fiber composite materials are widely used in automotive interior, functional parts and structural parts. Replacing traditional metal materials with long fiber composite materials can not only reduce the weight of automobiles, but also simplify the production process and modular production. General Motors, one of the world's biggest carmakers, has already applied fiberglass composites to the cargo boards of sport vehicles and pick-up trucks. Ford is one of the leaders in the use of composite materials, producing cars that use fiber-reinforced sheet plastic as body insulation. In 2011, PP-LGF50 material was used in the driver's seat of a certain type of car produced by BMW, which reduced the weight of the car seat by 63% and also increased the service life of the car seat.

4. Application of long fiber composite material in car seat

4.1 Improve the service life and safety of the seat
The fatigue resistance of long fiber composites is relatively high. It has more matrix, and its fatigue fracture will not break out suddenly, but slowly expand from matrix to collective interface and fiber. Therefore, people can find the damage of long fiber composite materials in advance, and take corresponding remedial measures in time, effectively improve the service life of the seat. In addition to fatigue resistance, long fiber composite materials also have stable safety. If overloaded components are made of this material, the role of the car seat will not disappear immediately, but a small number of fibers will be broken first, and the load will be quickly redistributed and transferred to the fibers that are not damaged, so that the whole component will not be broken by heavy objects in a short time.

4.2 Reduce the vibration amplitude of the seat
There is a large damping between the interface of the long fiber composite and the matrix, and it has a good vibration damping performance. When the long fiber composite with the same size and shape is subjected to the vibration test under the same conditions, the decay time of the former is shorter than that of the latter. Therefore, the vibration frequency and duration of the seat are reduced effectively by using the long fiber composite material.

4.3 Reduce seat cost
In the processing of long fiber composites, no chemical reaction is required, and the reinforced fiber is directly extruded in a predetermined direction and arranged at the same time
On the matrix, the layered structure is formed and pressed on the high speed hydraulic press, so that the long fiber composite can be processed. This method not only saves the cost of buying semi-finished products and reduces the manufacturing cost, but also guarantees the fiber length and optimizes the mechanical properties of the component [3]. In addition, long fiber composite parts can be made by combining the matrix with the fiber and then using the mold for heating and curing. In this process, the matrix changes from fluid to solid, so the car seat made of long fiber composite material is not easy to generate cracks.

4.4 Reduce the damage degree of the seat at high temperature
Long fiber material can achieve the effect of high temperature resistance in general conditions, ordinary aluminum alloy in 4 ℃, its elastic modulus will be greatly reduced, but under the same conditions, the use of long fiber material after the reinforcement of aluminum alloy, its elastic modulus and strength can remain unchanged. Because of the low thermal conductivity of long fiber composite, its high temperature resistance is better. The application of long fiber composite material to car seat can effectively reduce the damage degree of car seat under high temperature condition.

4.5 Maintain the stability of various performance of the seat
Among the many characteristics of long fiber composites, high specific stiffness and high specific strength are more significant, and their properties have a wide range of variation. According to the different fiber materials, fiber content and the direction of spreading, the designed product strength index, flame retardant property and elastic modulus are also different. When the long fiber composite material is stretched in one direction, the material can be extended perpendicular to the stretching direction. This property is completely different from that of common materials. In the design process of car seats, materials that are easy to design and can maintain stable performance should be selected. Long fiber composite materials can flexibly design different shapes while maintaining stable performance in all aspects.

5.Conclusion

Car seat as the bearing capacity of the car parts, in traffic accidents to ensure the safety of the vehicle has a very important role, therefore, towards lightweight, comfortable safety and other aspects of the development of car seat is the inevitable trend. Long fiber composite materials have a variety of excellent performance, improve the quality of the car seat while reducing its quality, improve the performance at the same time reduce the cost, thus, with the rapid development of the automobile industry and the development of long fiber composite materials in the technical level of the continuous improvement, in the car seat, long fiber composite materials application prospects will be increasingly broad.