Overlapping Bonded Structure With Recesses to Prevent Hole Breakage
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Solution Overview
Problem
Existing lap joint structures using mechanical or friction joining methods for overlapping sheet members are prone to failure due to strain concentration at holes, leading to breakage starting from these points under tensile deformation.
Innovation Solution
The introduction of cutaway recessed parts between adjacent joined parts in the overlapping sheet members disperses strain, preventing breakage from occurring at the holes formed by mechanical joining means.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical joining means or friction stir spot joining is used to join overlapping sheet members, then the materials can be joined without melting, but holes are formed at the joined parts causing strain concentration and breakage under tensile deformation
Solution Approach 1:
The patent applies local quality by creating cutaway recessed parts at specific locations (overlapping parts between adjacent joined parts) rather than modifying the entire structure. This localized modification redistributes strain in the critical hole regions while maintaining the overall structural integrity and joining effectiveness.
Solution Approach 2:
The patent segments the continuous sheet member by introducing cutaway recessed parts that divide the material continuity in a controlled manner. This segmentation creates strain distribution pathways that prevent concentration at hole edges, effectively breaking the strain concentration mechanism while maintaining structural coherence.
2Strength
If spot welding is used to join steel sheet members with high tensile strength, then the tensile strength is maintained, but the toughness of nuggets falls and stress concentrates at nugget ends
Solution Approach 1:
The patent extracts the problematic stress concentration zones by introducing cutaway recessed parts that remove material in strategic locations. This extraction eliminates the stress concentration points at nugget ends while preserving the high strength characteristics of the welded joints.
3Ease of manufacture
If holes are formed for mechanical joining means, then the sheet members can be joined, but strain concentrates at the holes causing breakage starting from these points
Solution Approach 1:
The patent applies local quality by creating cutaway recessed parts at specific locations (overlapping parts between adjacent joined parts) rather than modifying the entire structure. This localized modification redistributes strain in the critical hole regions while maintaining the overall structural integrity and joining effectiveness.
Solution Approach 2:
The patent segments the continuous sheet member by introducing cutaway recessed parts that divide the material continuity in a controlled manner. This segmentation creates strain distribution pathways that prevent concentration at hole edges, effectively breaking the strain concentration mechanism while maintaining structural coherence.
Data Source
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Figure 3(A)~4(C)
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AI summary
The present invention provides an overlapping bonded structure in which breaking of a bonded section at holes formed during bonding can be prevented when an overlapping section formed by overlapping a plurality of meal plate members is bonded by means of a mechanical bonding means or a friction stir spot-welding means. This overlapping bonded structure, in which overlapping portions of a plurality of plate members are spot-welded at a plurality of bonded sections by means of a mechanical bonding means or a friction stir spot-welding means, and in the bonded sections a hole into which the mechanical bonding means is inserted or a hole formed during the spot-welding by the friction stir spot-welding means exists in at least one plate member, is characterized in that a cutout recess is formed between adjacent bonded sections, from an end portion of the overlapping section in the bonded-section direction, in the overlapping section of at least one of the plate sections, and when the inner diameter of the hole is K, an inside bottom portion of the cutout recess is formed at a position having a depth of K or greater from the end portion of the overlapping section.