Fillet Welded Joint Press Bead Fatigue Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current fillet welded joints in automotive chassis members suffer from low fatigue strength due to stress concentration at the weld toe and root, leading to fatigue cracks, and existing methods to improve this are either ineffective or increase production costs and complexity.
Innovation Solution
The formation of a press bead on the surface of the metal members before fillet welding, which projects upward to contact or overlap the weld bead, increases the rigidity and reduces stress concentration, thereby enhancing the fatigue strength without the need for additional stiffening beads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If post-processing is performed to increase the flank angle by grinding the weld toe or remelting the toe by TIG welding, then the fatigue strength is improved, but the production cost and process complexity increase
Solution Approach 1:
The patent applies preliminary action by forming a press bead on the metal member surface before fillet welding occurs. This pre-formed press bead modifies the surface geometry in advance, creating an optimized bead profile that reduces stress concentration at the weld toe without requiring subsequent post-processing operations like grinding or TIG remelting.
Solution Approach 2:
The invention extracts the stress concentration problem from the weld toe by introducing a separate press bead structure. This press bead is formed independently through press-forming and then overlaid with the weld bead, effectively separating the stress distribution function from the welding process itself.
2Reliability
If additional stiffening beads are added to reduce stress concentration, then the fatigue strength is improved, but the welding process complexity and production time increase
Solution Approach 1:
The press bead is formed in advance through press-forming before the welding operation. This preliminary formation of the reinforcing structure eliminates the need for additional welding passes or stiffening beads, as the press bead already provides the necessary structural reinforcement to reduce stress concentration.
Solution Approach 2:
The invention replaces the mechanical welding process with a press-forming operation to create the reinforcing bead structure. Instead of using additional welding to form stiffening beads, a mechanical press-forming process is used to create the press bead, which is then overlaid with the weld bead, reducing overall process time.
3Reliability
If the weld bead is extended or augmented to ease stress concentration at the weld toe, then the fatigue strength is improved, but the manufacturing complexity increases
Solution Approach 1:
The press bead acts as an intermediary structure between the base metal and the weld bead. This intermediate press-formed bead modifies the surface geometry and stress distribution, facilitating easier welding by providing a pre-prepared surface that reduces stress concentration without requiring complex weld bead augmentation techniques.
Solution Approach 2:
The surface geometry is preliminarily modified by forming the press bead before welding. This pre-modification of the surface creates optimal conditions for welding that reduce stress concentration, eliminating the need for complex weld bead extension or augmentation operations after welding.
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 improves the fatigue strength of fillet welded joints by reducing stress concentration and preventing cracks, while simplifying the welding process and reducing production costs, making it suitable for complex shapes and mass production.
Implementation Method 1
The formation of a press bead on the surface of the metal members before fillet welding, which projects upward to contact or overlap the weld bead, increases the rigidity and reduces stress concentration
Implementation Method 2
a press bead of a rib-shaped projection provided by press-forming so as to project upward
Data Source
AI summary
The present invention provides a fillet welded joint and a method of production of a fillet welded joint which can raise the productivity of the method of production of a fillet welded joint and a fillet welded joint without sacrificing the strength against fatigue fracture of the welded structural member. The fillet welded joint of the present invention is a fillet welded joint formed by fillet welding at least two metal members, wherein, on the surface of at least one of the metal members, the fillet welded joint comprises a press bead of a rib-shaped projection provided by press-forming so as to project upward to the side having a weld bead formed by the fillet welding, and part of the press bead contacts or overlaps the weld bead.