Polymeric Crash Box with Rear Stiffening for Angled Impact Stability
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Solution Overview
Problem
Polymeric crash boxes in motor vehicles face instability and sudden failure during angled crashes due to bending moments and stress intensification at the rear extremity, leading to potential deformation and reduced functionality.
Innovation Solution
A polymeric crash box with integrated stiffening means at the rear extremity, featuring a hexagonal channel structure and tapered channels to enhance stability and absorbency, maintaining energy absorption capacity without increasing volume or weight, and incorporating inclined faces to distribute stress effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the crash box has a polymeric alveolar structure to reduce weight and maintain rigidity, then weight and energy absorption are improved, but stability during angled crashes deteriorates due to bending moments causing sudden failure at the rear extremity
Solution Approach 1:
The patent applies local quality by creating a non-uniform alveolar structure where the cell geometry varies along the longitudinal axis. Specifically, the front portion has a first alveolar structure optimized for energy absorption, while the rear portion has a second alveolar structure with different geometric parameters optimized for stability. This local differentiation allows the structure to simultaneously achieve weight reduction through the alveolar design while preventing bending-induced failure at the rear extremity through enhanced local rigidity.
2Use of energy by moving object
If the crash box is designed to collapse from frontal portion towards rear portion to absorb kinetic energy, then energy absorption capacity is improved, but reliability deteriorates when support elements fail causing intensified stresses and potential collapse from rear extremity
Solution Approach 1:
The patent applies preliminary anti-action by designing the rear portion's alveolar structure with geometric parameters that preemptively counteract the destabilizing effects of bending moments and stress intensification. The second alveolar structure is specifically configured to resist collapse initiation at the rear extremity, thereby preventing the harmful effect of sudden failure even when support elements experience intensified stresses during the crushing process.
3Ease of manufacture
If the crash box uses a uniform alveolar structure throughout, then manufacturing simplicity is improved, but performance deteriorates because the structure cannot simultaneously optimize for both energy absorption and stability under angled crash conditions
Solution Approach 1:
The patent applies parameter changes by varying the geometric parameters of the alveolar structure along the longitudinal axis. The first alveolar structure in the front portion has specific geometric parameters optimized for kinetic energy absorption, while the second alveolar structure in the rear portion has different geometric parameters optimized for stability under bending moments. This gradual parameter transition allows the structure to adapt to different crash conditions while remaining manufacturable through injection molding processes.
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 solution provides enhanced stability and constant collapsing force during crashes while minimizing the risk of rear portion collapse, maintaining energy absorption efficiency and reducing production costs.
Implementation Method 1
Each crash box is in fact designed for having in the case of crash a permanent plastic deformation and a programmed collapse starting from a frontal portion towards a second rear portion
Implementation Method 2
having a substantially alveolar structure, in such a way to have a good impact strength and high rigidity
Data Source
Figure 1~2
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AI summary
Crash box (10) for a motor vehicle, realized in polymeric material and having a first open frontal extremity (12) and a second rear extremity (14). The crash box (10) besides comprises a structure (20) substantially alveolar defined by a plurality of channels (30) realized in just one piece, each of which extends internally to the crash box (10) starting form the first open frontal extremity (12) towards the second rear extremity (14). The crash box comprises stiffening means (50) of the second rear extremity (14) which are able to stiffen the plurality of channels (30) only in proximity of the second rear extremity (14). Preferably the stiffening means (50) are directly integrated with the second rear extremity (14), in particular internally to the same, and them are realized preferably in a polymeric material having a good impact strength.