Crash Box Weld Bead Geometry for Buckling Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing crash boxes have weld beads with reduced strength and potential crack formation due to short distances between trigger means, which compromises their ability to absorb impact energy effectively during a crash.
Innovation Solution
A crash box design featuring U-shaped members with longer weld beads connecting the intermediate portions between trigger means, ensuring increased strength and optimal loading distribution, with weld bead shapes varying from straight to S-shaped and bow-shaped configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between adjacent trigger means is kept relatively short to control buckling behavior, then the buckling control is improved, but the weld bead strength is reduced and crack formation risk increases
Solution Approach 1:
The patent applies local quality by creating a non-uniform weld bead geometry along its length. The weld bead has maximum width at the intermediate portion (between trigger means) and reduced width at the ends (at trigger means). This local variation in weld geometry concentrates strength where needed (intermediate portion) while maintaining adequate connection at trigger means, resolving the contradiction between short weld length and weld strength.
Solution Approach 2:
The patent employs curved/S-shaped weld bead geometry instead of a straight weld bead. The weld bead extends with curvature between trigger means, increasing its effective length and strength without increasing the linear distance between trigger means. This curved path allows the weld to better distribute stresses and resist cracking while maintaining compact trigger means spacing for buckling control.
2Strength
If the weld bead length is increased to improve strength, then the weld bead strength is improved, but the distance between trigger means increases which affects buckling control
Solution Approach 1:
The patent resolves the length contradiction by transitioning from a one-dimensional straight weld bead to a two-dimensional curved/S-shaped weld bead. The weld bead gains length through curvature in the plan view, allowing increased weld metal volume and strength without increasing the linear distance between trigger means. This dimensional approach enables the weld to span the same distance while having greater effective length for strength.
3Device complexity
If the weld bead is made shorter to maintain compact trigger means spacing, then the buckling control is maintained, but crack formation risk increases
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameters of the weld bead - specifically the width distribution and curvature radius. The weld bead has maximum width at the intermediate portion and tapered ends, with a controlled curvature radius that optimizes stress distribution. These parameter changes enable the short weld to resist cracking by concentrating strength where stress is highest (intermediate portion) while maintaining compact overall dimensions.
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
Enhances the strength of weld beads and reduces crack formation, thereby improving the crash box's ability to absorb impact energy and maintain structural integrity during collisions.
Implementation Method 1
said upper and lower members being welded together at areas along a trim edge of respective legs of the U-shaped members except for the trim edge formed between respective legs of respective trigger means
Implementation Method 2
The crash box is designed to absorb by buckling and plastic deformation at least some of the impact energy originating from a crash
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a crash box (3) comprising two generally U-shaped members (11, 12) having legs (11a, 12a) and provided at respective leg with at least two adjacent trigger means (13) and an intermediate portion (14) formed between said trigger means (13). The U-shaped members (11, 12) is welded together at areas along a trim edge (15) except for the trim edge (15) formed between respective legs of respective trigger means (13) so as to form a crash box (3) having aligned trigger means (13) and intermediate portion (14). The trigger means (13) are arranged normal to crash box (3), and the intermediate portion (14) of respective leg (11a, 12a) is welded together at the trim edge (15) thereof by a weld bead (20) having a length (L) which is longer that the shortest length (l) between two adjacent trigger means (13). The invention also relates to a method for producing such a crash box.