Bumper Back-Beam Composite Structure for Weight and Strength Trade-off
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Solution Overview
Problem
Current vehicle bumper back-beams face challenges in balancing strength and weight, with GMT materials providing improved shock resistance but failing in high-speed collisions, and composite solutions complicating the manufacturing process while increasing weight.
Innovation Solution
A bumper back-beam composed of a glass fiber mat reinforced plastic composite and a carbon fiber reinforced plastic composite, with specific weight percentages and arrangements of polypropylene, glass fibers, and carbon fibers, enhancing mechanical properties and reducing weight by optimizing the distribution of materials and their orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the strength of the bumper back-beam is increased, then the collision resistance is improved, but the weight and cost are increased
Solution Approach 1:
The bumper back-beam uses a composite structure combining GMT (glass fiber mat thermoplastic) and thermoplastic resin. The GMT provides high strength and shock resistance through glass fiber reinforcement, while the thermoplastic resin matrix binds the fibers and provides ductility. This composite approach achieves high collision resistance without the weight penalty of solid metal construction.
Solution Approach 2:
The bumper back-beam features localized reinforcement where needed. The GMT is positioned in specific areas requiring enhanced strength and shock absorption, while other areas use lighter thermoplastic resin. This allows the structure to have varying material properties - stronger where collision forces are concentrated, lighter where less strength is required - optimizing the strength-to-weight ratio.
2Strength
If GMT material is used to improve shock resistance, then the low-speed collision performance is improved, but the high-speed collision resistance deteriorates
Solution Approach 1:
The invention modifies the material parameters of GMT by controlling the glass fiber content (35-45 wt%), resin content (45-60 wt%), and adding crosslinking agents (0.1-10 wt%). These parameter adjustments optimize the balance between shock absorption (for low-speed collisions) and structural integrity (for high-speed collisions). The crosslinking agent specifically enhances high-speed collision resistance by creating a more rigid network structure.
Solution Approach 2:
The combination of glass fiber mat and thermoplastic resin creates a composite material with complementary properties. The glass fiber mat provides shock absorption and energy dissipation for low-speed impacts, while the thermoplastic resin matrix maintains structural coherence and prevents catastrophic failure in high-speed collisions. The composite structure allows both functions to coexist.
3Strength
If steel is inserted in GMT to improve strength, then the collision resistance is improved, but the weight reduction is limited
Solution Approach 1:
The invention uses glass fiber mat as the reinforcement material instead of steel. Glass fibers provide high strength-to-weight ratio, maintaining collision resistance while significantly reducing weight compared to steel. The thermoplastic resin matrix effectively binds the glass fibers, creating a lightweight composite structure that achieves the required mechanical properties without heavy metal content.
Data Source
AI summary
A bumper back-beam for a vehicle is provided. The bumper back beam includes a glass fiber mat reinforced plastic composite and a carbon fiber reinforced plastic composite disposed within the glass fiber reinforced plastic composite. The glass fiber mat reinforced plastic composite includes polypropylene at about 45 to 60 wt. %, glass fiber at about 35 to 45 wt. %, a crosslink agent at about 0.1 to 10 wt. %, peroxide at 0.1 to 4 wt. %, and an antioxidant at about 0.1 to 4 wt. %. The carbon fiber reinforced plastic composite includes a thermoplastic resin at about 40 to 60 wt. % and a carbon reinforced fiber at about 40 to 60 wt. % arranged in a predetermined direction.