Front Bumper Bracket Structure for Rigidity and Collision Stroke
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Solution Overview
Problem
Vehicles with high vehicle-height face challenges in maintaining support rigidity and assembling accuracy of the bumper face while ensuring sufficient collision stroke during frontal collisions, as the long moment arm can compromise support rigidity and energy absorption.
Innovation Solution
The implementation of a bracket system with high-rigidity portions and strategically positioned fragile portions, such as bead and recess features, that can bend and deform during collisions to absorb energy and protect pedestrians, while maintaining support rigidity and assembling accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the vehicle-body member is retreated together with the bonnet to meet pedestrian protection requirements, then pedestrian safety is improved, but the support rigidity and assembling accuracy of the bumper face deteriorate due to the long moment arm
Solution Approach 1:
The bracket is designed with localized high-rigidity portions (such as thickened sections or reinforced areas) at specific locations to provide sufficient support rigidity for the bumper face, while other portions maintain flexibility for collision deformation. This local reinforcement allows the bracket to simultaneously achieve both pedestrian protection through retreat capability and adequate support rigidity despite the long moment arm.
2Strength
If the bracket is designed with high rigidity to improve support rigidity and assembling accuracy, then bumper face stability is improved, but the collision stroke is reduced due to excessive structural stiffness
Solution Approach 1:
The bracket incorporates high-rigidity portions only at specific locations where support is needed, rather than making the entire bracket uniformly rigid. This localized reinforcement maintains adequate support rigidity and assembling accuracy for the bumper face while allowing other portions of the bracket to deform during collision, thereby preserving sufficient collision stroke for energy absorption.
Solution Approach 2:
The bracket's rigidity parameters are varied spatially along its structure, with higher rigidity values at support-critical locations and lower rigidity values at deformation zones. This parameter variation enables the bracket to provide necessary support stability while maintaining the flexibility required for adequate collision stroke and energy absorption.
3Length of moving object
If the bracket is made flexible to ensure collision stroke, then energy absorption is improved, but the support rigidity and assembling accuracy of the bumper face deteriorate
Solution Approach 1:
The bracket features localized high-rigidity portions positioned at critical support and attachment locations to ensure adequate assembling accuracy and bumper face stability. Meanwhile, other portions of the bracket are designed with appropriate flexibility to maintain sufficient collision stroke for energy absorption during frontal collisions.
4Loss of energy
If the longitudinal distance between the bumper-face support member and the vehicle-body member is increased to allow retreat, then collision energy absorption is improved, but the moment applied to the vehicle-body member becomes large
Solution Approach 1:
The bracket incorporates localized high-rigidity portions to strengthen the structure at critical locations, enabling it to withstand the large moment forces generated by the long moment arm during normal operation. This localized reinforcement allows the bracket to maintain structural integrity while still providing sufficient flexibility for collision deformation and energy absorption.
Data Source
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AI summary
There are provided a vehicle-body member (15, 17) provided at a vehicle-body front portion, a bumper-face support member (18) supporting a bumper face (3) in front of the vehicle-body member (15, 17), and plural brackets (20) fixedly connecting the vehicle-body member (15, 17) and the bumper-face support member (18). The bracket (20) comprises an inclination portion (26) which is inclined such that a front side thereof is positioned on an inward or outward side, in the vehicle width direction, of the bracket (20), a high-rigidity portion (63U, 63D), at least part of which is positioned at the inclination portion and which is configured to have high rigidity against an input of a load applied in a vehicle longitudinal direction, and a fragile portion (62, 61f, 61r) which is configured to be deformable by receiving the input of the load applied in the vehicle longitudinal direction. The high-rigidity portion (63U, 63D) and the fragile portion (62, 61f, 61r) are provided adjacently to each other in the vehicle longitudinal direction.