Lap Fillet Arc-Welded Joint Stress Concentration Reduction
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Solution Overview
Problem
Current lap fillet arc-welded joints in automotive parts are prone to fatigue failure at the weld toe due to stress concentration, and existing methods to enhance fatigue strength either increase costs or man-hours, with no inexpensive solution available.
Innovation Solution
A lap fillet arc-welded joint design where the weld toe is positioned on a sloped portion of a protruding curved surface, reducing stress concentration and increasing the radius of curvature, thereby decreasing the weld bead height and enhancing fatigue strength without increasing costs or man-hours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lap fillet arc welding is used to join metal sheets, then the welding process is simple and cost-effective, but the weld toe experiences high stress concentration leading to fatigue failure
Solution Approach 1:
The patent applies curvature by forming a protruding curved portion on the metal sheet surface at the welding position. This curved geometry increases the radius of curvature at the weld toe, reducing stress concentration and preventing fatigue failure. The protruding portion creates a smoother transition zone that distributes stress more effectively compared to conventional flat joint configurations.
2Reliability
If existing methods such as multilayer weld structure or special shielding gas are used to increase fatigue strength, then fatigue strength improves, but manufacturing cost and man-hours increase
Solution Approach 1:
The patent implements preliminary action by forming the protruding curved portion on the metal sheet before the welding process. This pre-formed geometry prepares the joint configuration to reduce stress concentration during welding, eliminating the need for post-welding treatments, special gases, or multilayer welding procedures. The curvature is created in advance through forming processes, making the subsequent welding simpler and more cost-effective.
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 effectively reduces stress concentration at the weld toe, increasing the fatigue strength of the joint and preventing fatigue failure, while maintaining cost-effectiveness and efficient welding processes.
Implementation Method 1
a weld toe is positioned on a sloped portion, on a to-be-welded side, of the protruding curved portion... welding an end portion of one sheet of the two metal sheets to a surface of the other sheet along the end portion of the one sheet
Data Source
Figure 1~2(b)
Figure 3~4
Figure 5~6
AI summary
The lap fillet arc-welded joint (1) pertaining to the present invention is characterized in that two plates (3, 9) are lapped, and the surface of a first plate (vertical wall section (9a) of an upper-side component (9)) and the surface of a second plate (vertical wall section (3a) of a lower-side component (3)) are welded along the end section of the first plate (vertical wall section (9a) of the upper-side component (9)), wherein a curved convex section (5) in the form of a bead protruding to the surface side of the vertical wall section (3a) is provided, and a weld toe section (1a) is provided to the top section of the curved convex section (5).