Bumper Reinforcement Mounting Shear Control
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Solution Overview
Problem
High tensile strength steel or aluminum bumper reinforcements tend to split at bolt fastening points during collisions, leading to reduced load transmission to vehicle body skeleton members, especially under high collision loads.
Innovation Solution
A bumper reinforcement mounting structure with a first mounting member that has a lower shear strength than the mounting portion of the bumper reinforcement, ensuring it breaks earlier and maintains load transmission paths to both sides of the vehicle body skeleton members, using bolts with controlled shear strength to prioritize earlier failure over the reinforcement itself.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high tensile strength steel or aluminum bumper reinforcement is used, then strength is improved, but the bumper reinforcement is more likely to split at the bolt fastening portion during collision
Solution Approach 1:
The patent changes the material parameters by using high tensile strength steel sheets with tensile strength of 980 MPa or higher but not exceeding 1470 MPa, and controlling the thickness to 1.0 mm or more. This parameter optimization allows the bumper reinforcement to achieve high strength while maintaining sufficient ductility to prevent splitting at fastening portions during collision
Solution Approach 2:
The patent introduces a control rod that can dynamically change the stiffness of the bumper reinforcement. By adjusting the control rod's position or engagement state, the system can adapt the reinforcement's mechanical properties to balance strength and ductility requirements under different collision conditions, preventing brittle failure at fastening portions
2Strength
If the bumper reinforcement is made of high tensile strength material, then strength is improved, but ductility is reduced making splitting more likely
Solution Approach 1:
The patent optimizes material parameters by selecting high tensile strength steel sheets with tensile strength in the range of 980-1470 MPa and controlling the thickness to 1.0 mm or more. This parameter control ensures the material maintains adequate ductility even at high strength levels, preventing brittle behavior during collision
Solution Approach 2:
The patent employs composite construction by combining the high tensile strength steel sheet or aluminum member with a control rod mechanism. This composite system allows the main reinforcement to provide strength while the control rod adds ductility and energy absorption capability, preventing catastrophic splitting
3Force
If the bumper reinforcement is rigid to transmit load effectively, then load transmission is improved, but the mounting portion is more likely to break under high collision load
Solution Approach 1:
The patent designs the mounting portion with pre-calculated and optimized strength characteristics that match the control rod's breaking strength. This preliminary design ensures that under high collision loads, the mounting portion and control rod fail in a controlled manner before the main bumper reinforcement, preventing catastrophic failure while ensuring adequate load transmission during normal operation
Solution Approach 2:
The patent incorporates a control rod that acts as a sacrificial element with controlled breaking strength. This element provides beforehand cushioning by failing first under extreme loads, protecting the main bumper reinforcement and mounting structure from catastrophic failure while still transmitting the majority of collision loads to the vehicle body skeleton members
Data Source
AI summary
A bumper reinforcement mounting structure includes a plurality of vehicle body skeleton members disposed at an interval in a vehicle width direction and extending in a vehicle front-rear direction, a bumper reinforcement that extends in the vehicle width direction and is mounted on the vehicle body skeleton members, and a first mounting member that is used to mount a mounting portion of the bumper reinforcement on one of the vehicle body skeleton members. The first mounting member has shear strength that is lower than shear strength of the mounting portion of the bumper reinforcement.