Variable Stiffness Bumper Energy Absorber for Pedestrian Protection
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Solution Overview
Problem
Existing vehicle bumpers face challenges in balancing energy absorption for pedestrian protection with the need to minimize low-speed damage to the vehicle, while also adhering to design aesthetics and space constraints.
Innovation Solution
An energy absorber design featuring a reinforced element, first and second ribs, and a skin portion that provides variable stiffness by transitioning from a first stiffness for initial displacement to a second, greater stiffness as the ribs pivot and lock against the reinforced element, allowing for tailored energy absorption and protection across different impact ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the bumper provides high energy absorption for pedestrian protection, then pedestrian safety is improved, but the bumper becomes too soft and causes increased damage to the vehicle during low speed impacts
Solution Approach 1:
The bumper incorporates a deformable energy absorber with a movable rib that transitions between different positional states. During pedestrian impact, the rib moves from a first position to a second position, enabling the structure to deform and absorb energy. During low-speed vehicle impacts, the rib remains in the first position, providing increased stiffness to minimize damage. This dynamic reconfiguration allows the bumper to adapt its mechanical properties based on the type of impact encountered.
Solution Approach 2:
The energy absorber changes its stiffness parameter based on the impact conditions. By transitioning the rib between positions, the structural parameters of the bumper are modified - moving from a softer configuration optimized for pedestrian protection to a stiffer configuration optimized for minimizing vehicle damage during low-speed impacts.
2Strength
If the bumper is made stiffer to minimize low speed damage, then vehicle damage is reduced, but the energy absorption capability for pedestrian protection deteriorates
Solution Approach 1:
The bumper system dynamically adjusts its stiffness through the movable rib mechanism. When subjected to forces characteristic of pedestrian impacts, the rib transitions to a position that reduces overall bumper stiffness, enabling effective energy absorption. The system thus avoids the need for a permanently stiff bumper that would harm pedestrian safety.
3Object-affected harmful factors
If the energy absorber structure is made more complex to achieve variable stiffness, then both pedestrian protection and low-speed damage resistance are improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The energy absorber utilizes the impact force itself to drive the rib between positions. The structure is designed so that the applied load automatically triggers the transition from the first position to the second position, eliminating the need for external actuators, sensors, or control systems. This self-actuating mechanism reduces complexity while achieving variable stiffness functionality.
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 absorbs energy at low speeds to protect pedestrians and minimizes vehicle damage by adjusting stiffness based on displacement, ensuring compliance with both pedestrian protection and low-speed impact requirements.
Implementation Method 1
the rib is movable from a first position providing a first stiffness to a second position providing a second stiffness greater than the first stiffness
Implementation Method 2
An energy absorber for a motor vehicle includes a reinforced element, a skin portion, and a rib that provides variable stiffness
Data Source
AI summary
A bumper assembly for a motor vehicle includes an energy absorber providing a variable stiffness for different displacements. The energy absorber includes a skin portion attached to a bumper beam, a rib pivotally attached to an end of the skin portion and a reinforced element attached to an end of the rib. The rib is movable from a first position that provides a first stiffness for a first displacement to a second position providing a second stiffness greater than the first stiffness over a second displacement.