Vehicle Member Joining Structure to Prevent Ridge Line Cracking
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Solution Overview
Problem
Existing joining methods for vehicle members with ridge lines are prone to cracking due to the high stiffness and shared load of the ridge line portions during welding.
Innovation Solution
A joining structure and method that involves a first vehicle member with a ridge line and a second vehicle member with an overlapping ridge line, where a cut is made in the second vehicle member to expose the first ridge line, and fillet welding is performed along the cut to create a second welded portion, thereby reducing the load on the ridge line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If members having a ridge line are welded together by conventional lap fillet welding, then the joining strength is sufficient, but cracking occurs in the welded portion starting from the ridge line portion due to high stiffness and shared load
Solution Approach 1:
The welded portion is segmented into two distinct zones: a first welded portion at the end face and a second welded portion along the cut. This segmentation allows the second welded portion to avoid the high-stress ridge line area while still providing joining strength, thereby preventing cracking initiation at the ridge line portion.
Solution Approach 2:
The welding structure is made non-uniform by introducing a cut that creates different welding configurations at different locations. The second welded portion is specifically designed to be offset from the ridge line, creating a local quality difference that protects the high-stiffness ridge line area from welding-induced cracking while maintaining overall joining strength through the first welded portion.
2Reliability
If a cut is provided in the second vehicle member to expose the first ridge line and welding is performed along the cut, then cracking is reduced, but the weld length is increased which may affect manufacturing efficiency
Solution Approach 1:
The cut is formed in advance before the welding process. This preliminary action prepares the second vehicle member with the appropriate geometry that enables the second welded portion to be positioned optimally along the cut rather than across the ridge line, thereby preventing cracking before the welding operation begins.
3Reliability
If the second welded portion is not provided on the first ridge line, then cracking is prevented, but the joining strength may be insufficient
Solution Approach 1:
The first welded portion at the end face and the second welded portion along the cut are combined to provide comprehensive joining strength. The first welded portion contributes to overall strength while the second welded portion provides additional bonding area that compensates for the exclusion of welding on the ridge line, ensuring sufficient total joining strength without cracking.
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 approach effectively reduces cracking in the welded portion of the ridge line by distributing the load and increasing the weld length, thereby enhancing the fatigue strength and joining strength of the vehicle members.
Implementation Method 1
a first welded portion in which the second vehicle member is welded to the first vehicle member from outside by lap fillet welding
Data Source
AI summary
The skeleton member includes a cut and a welded portion, and the cut is formed in the skeleton member and extends along the ridge line so that the ridge line is exposed. In addition, in the welded portion, the skeleton member is welded to the skeleton member along the cut along the ridge line by fillet welding. In this way, no welded portion is provided on the ridge line. Since the rigidity in the ridge line portion is higher than the periphery and the shared load is also large, it is possible to reduce cracking starting from the ridge line portion by not providing the welded portion in the ridge line.