At present, high-speed railway is developing rapidly in the world, but with the continuous improvement of high-speed train speed, the traditional train made of metal materials faces the problems of strong vibration, high resistance and high noise. Especially in the complex and changeable environment such as high temperature, high cold and high altitude, including plateau and desert, the existing metal materials are exposed to the problems of poor shock absorption and sound insulation performance and high energy consumption.
Recently, the scientific research team of the International Bamboo and Rattan Center and Fujian Heqichang Bamboo Industry Co., Ltd. have made important progress in the development of renewable lightweight shock-absorbing rail transit vehicle floor materials with the strength and toughness of bionic bamboo. Inspired by the biological structure of bamboo, they proposed the design strategy of the laminary-structure of the floor of lightweight shock-absorbing rail transit vehicles, and simulated the preparation of composite materials with similar bamboo wall layer structure. This renewable lightweight damping damping composite material made of bamboo, wood and other natural green materials has the characteristics of lightweight shock absorption, flame retardant, fatigue resistance and impact resistance, and has become an important research and development direction of rail transit vehicle floor materials such as high-speed rail.
"At present, high-speed trains with an speed of 250 kilometers per hour use carbon steel and stainless steel as floor materials, but these two materials are dense, resulting in heavy carriages, high energy consumption, and susceptible to environmental corrosion, and a high corrosion margin needs to be set aside when designing." "For high-speed trains running at 350 km/h, the floor materials of the vehicles are mostly aluminum alloy and carbon fiber composite materials, which are less dense, consume less energy, have good ductility and corrosion resistance, but are expensive." International Bamboo and Rattan Center doctoral student Han Shanyu said that the above metal materials are non-renewable materials, shock absorption and sound insulation performance is poor.
Bamboo is a kind of natural fiber reinforced biomass composite material. After millions of years of natural evolution, it has formed a delicate and orderly gradient stratification, multi-pore structure and multi-layer interface. Gradient laminar structure refers to the fiber distribution density in the bamboo rod, which decreases from the epidermis to the inner layer along the bamboo wall, so the mechanical properties of the bamboo are also gradually changed, showing obvious functional gradient characteristics, and the bamboo structure is composed of fiber - fiber, fiber - parenchyma cell, parenchyma cell - parenchyma cell and other interfaces, so that it has natural toughness and damping properties.
Chen Fuming, an associate researcher at the International Bamboo and Vine Center, said that they imitated the structure and function of natural bamboo, and laminated several easily accessible materials of light and soft fast-growing artificial forest wood veneer with waste rubber veneer, and then placed the high-strength, high-hardness, and porous structure of bamboo carbon plastic board on the surface for secondary cold-pressing composite molding. A renewable lightweight damping damping composite material similar to bamboo with gradient layered structure, multi-pore structure and multi-layer interface is obtained. Damping helps to reduce the resonance amplitude of the material structure, avoid structural damage caused by the dynamic stress reaching the limit, so that the material can quickly return to a stable state, and reduce noise.
The composite material has the advantages of wide source of raw materials, renewable, pollution-free, low density, light weight, fatigue resistance, impact resistance, vibration reduction, sound insulation effect and excellent fire and flame retardant performance, which meets the comprehensive performance requirements of rail transit vehicle bottom plate.
Wang Ge, a researcher at the International Bamboo and Rattan Center, said that general bamboo and wood structural materials are often used in construction, decoration and furniture, and are less used in high-speed rail. Today, through research and innovation, the first batch of renewable lightweight damping composite materials with lightweight, high strength and high weather resistance have been successfully applied to the floor of some high-speed rail cars at 350 km/h, and can be widely promoted in the future on high-speed rail, subway, bus and other cars.
