Tunable Energy Absorber for Vehicle Hood Impact Mitigation
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Solution Overview
Problem
Modern vehicles face challenges in absorbing and dissipating energy during impulse events, such as collisions, due to densely packed hard components under the hood, which can lead to severe impacts on objects and increased damage.
Innovation Solution
A tunable energy absorber with a planar matrix of cells, each comprising interconnected elongate micro-elements, configured to vary in material composition, porosity, and structure across in-plane and out-of-plane directions, allowing for controlled deceleration of objects during impulse events, reducing peak deceleration and maintaining a low Head Injury Criteria (HIC) score.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hard components are densely packed under the hood, then engine compartment functionality is improved, but impulse severity and damage to impacting objects increases
Solution Approach 1:
A compliant layer is introduced as an intermediary between the hard engine compartment components and the hood. This compliant layer acts as a mediator that deforms during impulse events, absorbing energy and reducing the severity of impulses transmitted to objects contacting the hood, while allowing the hard components to remain in their functional positions.
Solution Approach 2:
The patent modifies the mechanical properties of the space between the hood and hard components by introducing a compliant layer with specific hardness and elasticity parameters. This changes the overall system's response to impulse, transforming it from a rigid structure to one that can deform and absorb energy, thereby reducing impulse severity while maintaining component functionality.
2Object-affected harmful factors
If a compliant layer is added between the hood and hard components, then impulse severity is reduced, but device complexity increases
Solution Approach 1:
The compliant layer serves multiple functions simultaneously: it acts as an energy absorber during impulse events, provides a sealing barrier between the hood and hard components, and maintains the structural integrity of the engine compartment. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
Solution Approach 2:
The compliant layer is described as having a porous or cellular structure, which allows it to deform and collapse during impulse events, absorbing energy efficiently. This porous structure also reduces the material quantity and weight compared to a solid compliant layer, helping to minimize the increase in device complexity.
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 energy absorber effectively reduces the severity of impulses by absorbing energy through controlled deceleration, minimizing peak loads and HIC scores, thereby enhancing safety and reducing damage to both the vehicle and impacting objects.
Implementation Method 1
Each cell has a respective energy absorption capacity wherein an energy absorption capacity of the energy absorber varies across at least one of the in-plane and out-of-plane directions. The cells are configured such that impulse of an object with the cover with the energy absorber sandwiched between the cover and the covered object, thereby defining an impulse event, causes a deceleration vs. time response in the object
Data Source
AI summary
An energy absorber for interposition between a cover and a covered object includes a generally planar matrix of cells. Each of the cells includes a plurality of generally elongate micro-elements interconnected to form a cell micro-structure, with each cell having a respective energy absorption capacity such that an energy absorption capacity of the energy absorber varies across at least one direction. The cells are configured such that impulse of an object with the cover with the energy absorber sandwiched between the cover and the covered object causes a deceleration vs. time response in the object, beginning with a generally linear rise in the deceleration to a peak deceleration within 5 ms after the beginning of the impulse event, followed by a generally nonlinear decrease in the deceleration over a period of not greater than 15 ms to a final target deceleration of not greater than 10% of the peak deceleration.