Bumper Assembly with Variable Stiffness Members for Impact Management
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Solution Overview
Problem
Vehicle bumpers face a design challenge in balancing energy absorption and stiffness during various impacts, such as collisions with larger objects and pedestrians, while also considering low-speed damageability, as existing designs struggle to optimize energy absorption and injury reduction simultaneously.
Innovation Solution
A bumper assembly design featuring a beam with sequentially arranged members having varying outer and inner tube diameters and wall thicknesses, which allows for adjustable stiffness and energy absorption based on impact type, providing reduced resistance for pedestrians and increased resistance for larger objects, while maintaining a rigid structure for low-speed impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the bumper is designed with greater stiffness to increase energy absorption during impacts with larger objects, then energy absorption is improved, but pedestrian injury risk increases due to higher resistance during deformation
Solution Approach 1:
The bumper assembly employs members with varying wall thicknesses and tube diameters at different locations. Specifically, members have different outer tube wall thicknesses and/or inner tube wall thicknesses, creating zones of different stiffness. This allows the bumper to provide higher stiffness and energy absorption for large object impacts while offering reduced resistance for pedestrian impacts, thereby resolving the contradiction between energy absorption and pedestrian safety.
2Reliability
If the bumper is designed to be rigid with no deformation to reduce exterior damage during low-speed impacts, then damageability is improved, but energy absorption capability deteriorates during higher-speed impacts
Solution Approach 1:
The bumper assembly is designed with members that can dynamically adjust their stiffness characteristics based on impact conditions. The varying wall thicknesses and tube diameters create a progressive deformation capability, allowing the bumper to remain relatively rigid for minor low-speed bumps while progressively deforming to absorb energy during more severe impacts. This dynamic response resolves the contradiction between maintaining rigidity for damage reduction and enabling deformation for energy absorption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively reduces pedestrian injuries by minimizing resistance during narrow object impacts and enhances energy absorption during wider object impacts, while minimizing exterior damage during low-speed collisions, thereby improving safety and reducing repair costs.
Implementation Method 1
Bumpers of vehicles are designed to absorb energy and/or transfer energy during vehicle impacts
Implementation Method 2
Adjacent ones of the members 36 are configured to contact each other when both adjacent ones of the members 36 are deformed
Data Source
AI summary
A bumper assembly includes a beam and a plurality of members attached to and positioned sequentially along the beam. Each member includes an outer tube extending transverse to the beam and an inner tube extending parallel to and in the outer tube. Adjacent ones of the members are configured to contact each other when both adjacent ones of the members are deformed.