Slotted Bumper Crossmember Structure to Protect Crash Box Joints
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Solution Overview
Problem
Bumper arrangements face issues with rupturing at the joint connection between the crossmember and crash boxes during vehicle impacts, particularly due to repeated deformation of the crossmember.
Innovation Solution
A crossmember with a slot or recess in its longitudinal direction, configured to dissipate crash energy and allow for controlled deformation, preventing direct transmission of deformation to the welded connection with crash boxes, and enhancing the welded seams' resistance to direct crash impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crossmember is rigidly connected to crash boxes via welded connections, then structural strength is improved, but the joint connection becomes vulnerable to rupturing during impacts
Solution Approach 1:
The crossmember is segmented by introducing slots or recesses that divide the continuous structure into sections. This segmentation allows different parts of the crossmember to deform independently during impact, reducing stress concentration at the welded joints while maintaining overall structural integrity.
Solution Approach 2:
The crossmember's structural parameters are changed by varying wall thickness, introducing slots or recesses, and creating non-uniform cross-sections. These parameter changes enable controlled deformation zones that protect the welded connections from excessive stress while maintaining necessary strength in critical areas.
2Loss of energy
If the crossmember is designed to absorb crash energy through deformation, then crash performance is improved, but the crossmember may undergo repeated deformation leading to joint rupturing
Solution Approach 1:
The slots or recesses are extracted from the crossmember structure to create dedicated deformation zones. These extracted regions allow the crossmember to undergo controlled deformation and energy absorption while isolating the welded joints from the deformation process, preventing joint rupturing even during repeated impacts.
Solution Approach 2:
The slots and recesses act as intermediaries between the impact force and the welded joints. They provide a transition zone that facilitates energy dissipation through controlled deformation while protecting the joint connections from direct exposure to crash forces.
3Reliability
If the crossmember is designed with slots or recesses to prevent joint rupturing, then joint reliability is improved, but manufacturing complexity increases
Solution Approach 1:
The crossmember utilizes thin-walled structures with integrated slots and recesses that can be efficiently manufactured using modern forming techniques. The thin-walled design allows for complex geometries including slots and recesses to be created through stamping or hydroforming processes, maintaining ease of manufacture while achieving the desired deformation characteristics.
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 slot in the crossmember design enhances crash performance by dissipating energy and preventing rupturing, allowing the bumper arrangement to withstand towing tests and maintain structural integrity during impacts.
Implementation Method 1
The slot is configured to dissipate crash energy and allow for controlled deformation, preventing direct transmission of deformation to the welded connection with crash boxes
Data Source
AI summary
A bumper arrangement, having a crossmember which is coupled via crash boxes to a motor vehicle, the crossmember having end regions, which project laterally beyond the crash boxes in the motor vehicle transverse direction, and attaching regions, in which the crash boxes are coupled to the crossmember, the crossmember being configured in cross section as a closed hollow profile, wherein a first slot which extends in the motor vehicle transverse direction is configured at least in longitudinal portions in the attaching region of a crash box in an upper wall, lower wall or a central bar of the crossmember, an outer end of the upper wall, lower wall and/or central bar being configured in one piece and from the same material continuously in the motor vehicle longitudinal direction.