Industry News
Research on Improving Low-Speed Crashworthiness of Automotive Structures with Aluminum Foam Filling
Aluminum foam, as a lightweight and high-energy-absorbing porous material, demonstrates significant advantages in low-speed crash protection for vehicles. By optimizing the design of filling structures, it can effectively absorb collision energy, reduce vehicle damage, and meet lightweight requirements. Below is an analysis from the perspectives of mechanism, structural design optimization, performance validation, and application challenges:
Mechanism of Aluminum Foam Filling Structures
- Energy Absorption and Dispersion
In low-speed collisions (e.g., 5-15 km/h), aluminum foam absorbs energy through pore collapse and plastic deformation. Its plateau stress (approximately 3-10 MPa) effectively cushions impact forces, reducing peak acceleration by 30%-50%, thereby lowering the risk of occupant injury.
The filling structure disperses impact loads through stress homogenization, avoiding localized stress concentrations that could cause sheet metal wrinkling or fracture.
- Synergistic Lightweight Effect
Aluminum foam has a density of only 1/5-1/3 that of solid aluminum. Replacing traditional steel or aluminum crash beams can reduce weight by 40%-60% while maintaining equivalent energy absorption. For example, after filling the front crash beam of a vehicle model with aluminum foam, the weight decreased from 3.2 kg to 1.8 kg, with a 25% improvement in low-speed crash energy absorption.
Optimization of Key Structural Parameters
| Parameter | Optimization Direction | Performance Impact |
| Filling Density | Gradient density design (low density in the core, high density on the surface) | Balances energy absorption efficiency and compressive strength, improving low-speed crash energy absorption by 15%-20%. |
| Filling Thickness | Adjusted based on collision zone requirements (e.g., 10-20 mm for bumper filling) | Increased thickness extends energy absorption time but requires balancing space occupancy and lightweight goals. |
| Interface Bonding | Combined adhesive + mechanical interlocking (e.g., honeycomb surface treatment) | Improves interface peel strength by 30%, preventing filling layer detachment during collisions. |
| Multi-material Composite | Outer carbon fiber-reinforced polymer (CFRP) panel + aluminum foam core | Increases bending stiffness by 50%, reducing residual deformation by 40% after low-speed collisions. |
Performance Validation and Case Studies
- Testing Methods
Sled Crash Test: After simulating a 15 km/h frontal collision, the energy absorption efficiency of the bumper system filled with aluminum foam reached 85% (compared to 65%- 70% for traditional structures).
Finite Element Simulation: Using LS-DYNA to simulate the compressive damage constitutive model of aluminum foam (e.g., Deshpande-Fleck model), the error in predicting structural deformation and acceleration curves was ≤8%.
- Engineering Application Cases
Front Side Member Filling in a New Energy Vehicle: Using gradient-density aluminum foam (0.4-0.8 g/cm³), low-speed collision repair costs were reduced by 35%, and bumper repairability was improved.
Door Anti-collision Beam Design: Filled with closed-cell aluminum foam (12 mm thickness), the side-impact intrusion was reduced by 18%, meeting C-NCAP 2024 low-speed crash requirements.
Technical Challenges and Future Directions
- Existing Issues
Cost and Manufacturing: High production cost of aluminum foam, and complex-shaped filling requires the development of precision casting or 3D printing processes.
Durability: Interface bonding performance may degrade under long-term vibration and temperature/humidity cycles (e.g., peel strength decreases by 20% after -40°C to 80°C cycles).
- Research Directions
Bio-inspired Structural Design: Drawing inspiration from honeycomb or bamboo fiber multi-level pore structures to optimize energy absorption efficiency and lightweight balance.
Smart Responsive Materials: Developing temperature/force-sensitive aluminum foam materials to dynamically adjust stiffness for different collision scenarios.
Circular Economy: Utilizing recycled aluminum to produce aluminum foam, reducing carbon emissions (production energy consumption can be reduced by 40%).
Conclusion
Aluminum foam filling structures offer both lightweight and high-energy absorption advantages in low-speed crash protection for vehicles. However, their large-scale application still requires overcoming challenges related to cost, process compatibility, and long-term reliability. Future advancements through **multidisciplinary collaborative design** (e.g., topology optimization, material genome engineering) and **green manufacturing technologies** are expected to promote their adoption in scenarios such as new energy vehicles and shared mobility, contributing to the automotive industry's safety and sustainable development goals.
