Aluminum Foam Revolutionizes Rail Transit: Lightweight and Multifunctional Applications Have Great Prospects

1. Aluminum Foam: “All-rounder” with excellent structure and functions

Aluminum foamis a kind of light metal material composed of aluminum matrix and three-dimensional holes, which is divided into two categories: through-hole and closed-hole. It has low density (<0.6 g/cm³), high strength (flexural strength of 16~24 MPa), and comprehensive properties such as sound absorption, sound insulation, fire prevention, heat insulation, energy-absorbing buffer, and electromagnetic shielding. Compared with plywood, aluminum honeycomb panels, and other traditional materials, aluminum foam is particularly outstanding in sound insulation (>20 dB), vibration isolation performance (>1 order of magNitude), and environmental protection, and has become an ideal choice for the lightweight and functional upgrade of rail trains.  

2. Application Scenario: All-round coverage from car body to station

Lightweight structural materials: Aluminum foam sandwich panels have been successfully applied to the floor, doors, linings, and other parts of high-speed rail and subway trains. For example, a domestic tram adopts a 10 mm thick foam aluminum sandwich panel floor, with remarkable sound insulation and vibration damping effect, and its service life can reach 30 years; the foam aluminum bumper developed by Siemens of Germany is used in bulk for the streetcar, and its energy absorption efficiency is improved by 50%.  

Expansion of functional materials:  

Noise reduction and sound insulation: Japan's Shinkansen adopts an aluminum foam sound insulation wall, which reduces generator noise by 20~40 dB; Korea's KM2 high-speed train carriages use aluminum foam material, and the sound insulation amount reaches 36 dB, far exceeding traditional materials.  

Energy-absorbing and explosion-proof: aluminum foam-filled train nose energy-absorbing device can absorb 50% of the energy of high-speed collision; subway tunnel wall-mounted aluminum foam lining, the explosion shock wave attenuation rate of 22%, significantly improving structural safety.  

Electromagnetic shielding: aluminum/foam aluminum composite electrical cabinet to improve electromagnetic shielding capacity of 40 dB, Japan's Shinkansen application, the noise outside the equipment down to 30~60 dB.  

3. Challenges and future: technological breakthroughs and standard improvement in parallel

Although the application of aluminum foam has a broad prospect, it still faces problems such as limited production size, high cost, and lack of uniform standards. Future research needs to focus on:  

• Optimize the control of hole structure to improve product consistency;  
• Promoting automated production processes to reduce costs;  
• Develop new products with large size and high performance;  
• Formulate industry standards to standardize the R&D and application process.  

Conclusion  

With the rail transit to an efficient, green direction, foam aluminum by its unique properties, is expected to play a greater role in the body's lightweight, safety protection environmental protection noise reduction, and other fields. Continuous breakthroughs in technology and the improvement of the industrial chain will accelerate the scale of this “future material” and provide solid support for the development of intelligent transportation.  

Related cases

Since 2007, Germany has used aluminum foam sandwich panels for high-speed railroad sound insulation panels, which are weather-resistant and have a sound insulation capacity of more than 20 dB;  

Shenzhen Metro Line 3 station roof panel foam aluminum exterior, the peak explosion stress is reduced by 59.7%, significantly improving safety performance.