Bumper Cross-Beam Bracket Layout to Prevent Absorber Joint Rupture
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Solution Overview
Problem
Bumper systems for motor vehicles often experience premature rupture at the connection between the cross beam and absorber due to high bending stiffness, leading to inadequate load management during crash impacts.
Innovation Solution
Incorporating an intermediate component with a lower bending stiffness than the cross beam, connected through specific contact areas, which acts as a trigger to deform and distribute impact forces, reducing the risk of rupture and enhancing load absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the cross beam is configured with high bending stiffness to prevent uncontrolled entering into the motor vehicle, then the structural strength is improved, but cracks occur at the connection between the absorber and the cross beam
Solution Approach 1:
A bracket is introduced as an intermediary component between the cross beam and the absorber. This bracket has a specific geometry with a free end that can deform under load, acting as a mediator that reduces stress concentration at the weld connections. The bracket's design allows it to absorb some of the impact energy through controlled deformation, preventing crack propagation in the heat affected zone of the welds.
Solution Approach 2:
The bracket's geometry is specifically designed with a free end portion that has lower stiffness compared to the main cross beam. This parameter change in local stiffness creates a compliant connection that can deform elastically during impact, reducing the transmission of high stresses to the weld joints while maintaining overall structural integrity.
2Device complexity
If the absorber is directly welded to the bumper cross beam to simplify the structure, then the device complexity is reduced, but the crash management system does not sustain sufficient load
Solution Approach 1:
The bracket serves as an intermediary element that, while adding a component, significantly enhances the load-sustaining capacity of the crash management system. The bracket's design with a free end allows for controlled deformation that distributes loads more effectively across the connection, enabling the system to sustain higher crash loads than a direct weld connection would allow.
Solution Approach 2:
The connection structure is segmented into distinct functional zones: the rigid cross beam, the compliant bracket with free end, and the absorber. This segmentation allows each component to perform its specific function - the cross beam provides structural support, the bracket provides compliant connection and stress distribution, and the absorber provides energy absorption - resulting in a more effective overall crash management system.
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 intermediate component effectively reduces the stiffness of the connection between the cross beam and absorber, preventing rupture and enabling the bumper system to sustain higher load impacts without damage, as demonstrated by improved energy absorption and load-displacement responses in crash tests.
Implementation Method 1
the intermediate component is connected to the rear wall of the cross beam through at least a first contact area... a part of the intermediate component distant from the longitudinal axis (LL) by a distance comprised between Lout and Dout has a smaller bending stiffness (Sinterm) about the vertical axis (Z) than a part of the cross beam
Implementation Method 2
Absorbers are configured so as to undergo deformation as a result of the impact and thus convert kinetic energy into deformation energy by cold deformation
Implementation Method 3
Absorbers are configured so as to undergo deformation as a result of the impact and thus convert kinetic energy into deformation energy by cold deformation
Data Source
Figure 1~2
Figure 3~4
Figure 5a~10
AI summary
A bumper system (4) for a motor vehicle comprising a cross beam (1) which is globally orientated in a transverse direction (Y), said cross beam comprising a front wall (6) adapted to receive a crash impact force and a rear wall (5) opposed and spaced from said front wall, at least one absorber (2), at least an intermediate component (3) to attach the absorber (2) to the cross beam (1), said intermediate component (3) being connected to the rear wall (5) through a first contact area (10), distant from a longitudinal axis (LL), by an internal component distance, called Lin and an external component distance, called Lout, which corresponds respectively to the minimum and maximum distance between said first contact area (10) and the longitudinal axis (LL), said longitudinal axis (LL) passing at mid width of the cross beam and being perpendicular to the transverse direction (Y), said intermediate component (3) being connected to the absorber (2) through a second contact area (20) distant from the longitudinal axis (LL) by an internal profile distance, called Din, and an external profile distance, called Dout, which corresponds respectively to the minimum and maximum distance between the second contact (20) area and the longitudinal axis (LL), wherein a part of the intermediate component distant from the longitudinal axis (LL) by a distance comprised between Lout and Dout has a smaller bending stiffness (Sinterm) about a vertical axis (Z) than a part of the cross beam distant from the longitudinal axis (LL) by a distance comprised between Lout and Din (Scross), said vertical axis (Z) being perpendicular to the transverse direction (Y) and the longitudinal axis (LL).