Bumper Crossbeam Crashbox Support for Lower Initial Impact Force
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Solution Overview
Problem
Existing bumper crossmembers require elaborate designs or additional process steps to reduce the initial energy absorption peak, which can exceed permissible forces during collisions.
Innovation Solution
The bumper crossmember design features crashboxes supported only in sections on the rear side of the crossmember, with continuous support in upper and lower end-face areas and selective support in lateral areas, allowing for controlled deformation and reduced initial peak force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crashbox is designed with uniform wall thickness, then the structural strength is maintained, but the initial energy absorption peak becomes excessively high
Solution Approach 1:
The crashbox is designed with non-uniform wall thickness where the wall thickness varies along the longitudinal extension. Specifically, the wall thickness is smaller in certain sections (e.g., adjacent to the crossmember) and larger in other sections, creating local quality differences that enable controlled deformation initiation at lower forces while maintaining overall structural strength
2Force
If the crashbox wall thickness is reduced to lower the initial peak, then the initialization force is reduced, but the manufacturing complexity and design elaboration increase
Solution Approach 1:
The wall thickness parameter of the crashbox is varied along its longitudinal extension to create a gradient structure. This parameter change allows the crashbox to exhibit different deformation characteristics in different sections, reducing the initial peak force while maintaining a relatively simple overall design that can be manufactured using conventional processes
3Force
If selective heating is applied to reduce crashbox strength in specific areas, then the deformation force is reduced, but additional process steps are required
Solution Approach 1:
Instead of using selective heating to modify material properties, the invention achieves local quality differences through variations in wall thickness during the manufacturing process. This approach reduces the initialization force by creating geometric variations rather than requiring additional thermal processing steps, thereby simplifying the manufacturing process
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
This design significantly reduces the initial energy absorption peak without altering the strength properties of the crashbox, achieving efficient energy absorption while maintaining manufacturing cost-effectiveness.
Implementation Method 1
Crashboxes are used to absorb impact energy by defined reshaping thereof. Thus, the energy to be absorbed is converted into forming energy.
Data Source
AI summary
A bumper cross member for a motor vehicle, having a crossmember extending transversely to the longitudinal axis of the vehicle, and two crashboxes connected thereto and designed as hollow chamber sections. Each crashbox is connected with its end facing away from the vehicle to the crossmember in a respective end section thereof, and may be connected, with its end facing the vehicle, to a structural component of the vehicle. The crashboxes are supported with their end faces only in sections on the rear side of the crossmember, in particular such that the support is continuous or at least substantially continuous either in the upper and lower end-face areas, or in the two lateral end-face areas, while support of the other end-face areas is provided only in sections or absent. The distance between the end-face areas of the crashboxes, which are unsupported on the crossmember, is set from the rear side of the crossmember, such that only after a first phase of energy absorption with deformation of the crashbox is the end face facing the crossmember supported over its whole surface on the rear side of the crossmember.