Bumper Assembly Crash Box Corners to Prevent Joint Break-Off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bumper assemblies are prone to joint failure between the cross member and crash boxes during a central impact, leading to the cross member being broken off, as the deformation concentrates stress at sharp corners.
Innovation Solution
A bumper assembly design featuring a cross member and crash boxes with chamfered or radiused external corners to distribute stress and improve weld quality, where the crash boxes are produced from light metal alloys and extruded components, and the chamfer or radius extends continuously over the corner, reducing stress concentration and enhancing energy absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cross member and crash boxes are joined using conventional screw or welded connections at sharp corners, then the assembly is structurally simple and easy to manufacture, but the joint is prone to breaking off during central impact due to stress concentration
Solution Approach 1:
The patent applies curvature by replacing sharp corners with radiused corners on the crash box cross-section. This geometric modification distributes stress more evenly during impact, preventing stress concentration at sharp edges and thereby improving joint reliability without significantly increasing manufacturing complexity
Solution Approach 2:
The patent modifies the geometric parameters of the crash box by introducing chamfers or radii at the corners. This parameter change transforms the stress distribution pattern, reducing peak stresses at the joint between the cross member and crash boxes during central impact events
2Loss of energy
If the cross member is designed to absorb crash energy through deformation, then the bumper assembly converts crash energy effectively, but the cross member itself may be deformed or broken off in central impacts
Solution Approach 1:
The patent applies local quality by differentiating the corner geometry of the crash box - specifically radiusing only the external corners that are subject to stress concentration during impact. This localized geometric modification protects the joint integrity while allowing the rest of the cross member to deform and absorb energy as intended
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 design enhances crash performance by distributing stress over a larger area, improving weld quality, and preventing the cross member from breaking off during impacts, while also providing improved energy absorption and reduced risk of stress peaks.
Implementation Method 1
due to the radius or the chamfer are distributed over a larger longitudinal region
Implementation Method 2
The crash boxes are coupled by a material connection to the cross member in the attachment regions and this is carried out, such as, by a welding process
Implementation Method 3
The crash boxes and the cross member are extruded components
Data Source
AI summary
A bumper assembly, having a cross member, which is coupled to a motor vehicle via crash boxes, wherein the cross member is oriented with its longitudinal direction in the motor vehicle transverse direction and on a rear wall has attachment regions in which the crash boxes are coupled by a material connection to the cross member, wherein in cross section a chamfer or a radius is configured on the crash boxes in an external corner, relative to the motor vehicle transverse direction.