Dissimilar Metal Joint Structure for Stress-Resistant Thin Plates

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Solution Overview

Problem

Existing methods for joining dissimilar materials, such as steel and aluminum, using rivets or spot welding machines do not achieve high joining strength, leading to stress concentration and potential fracture when a load is applied, especially in aluminum thin plates.

Innovation Solution

A dissimilar-material joining method where the second metal member is continuously pressed against the first metal member by a support member between welded spots, and bonded with adhesives to reduce stress concentration and enhance joining strength, using techniques like resistance spot welding, laser welding, or arc welding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rivets are used to join steel frame and aluminum thin plate, then the materials can be connected, but stress concentration occurs around the rivets causing fracture susceptibility

Engineering Contradiction:
Improvejoining strengthVSAvoidfracture resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

A support member is introduced as an intermediary component between the aluminum thin plate and the steel frame. This support member distributes the load over a wider area, preventing stress concentration at discrete rivet points. The support member acts as a mediator that transfers forces smoothly between the dissimilar materials, eliminating the harmful stress concentration effect while maintaining the structural connection.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention combines multiple joining methods (welding, adhesive bonding, and mechanical support) into a hybrid joining system. By merging these different connection techniques, the system achieves both strong structural attachment and stress distribution, resolving the contradiction between connection strength and fracture resistance that plagues single-method joining approaches.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If the number of riveted points is increased to prevent rivet fracture, then rivet reliability improves, but the distance between riveted points decreases making the thin plate more susceptible to fracture

Engineering Contradiction:
Improverivet retentionVSAvoidthin plate integrity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The support member serves as a load-distributing intermediary that eliminates the need for multiple discrete rivets. By providing a continuous or widely distributed support structure, it maintains rivet reliability while preventing the thin plate from experiencing the harmful effect of closely spaced rivet holes, thus preserving plate integrity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention transitions from a point-based joining approach (discrete rivets) to a distributed or continuous support approach. This dimensional change in the support structure allows load distribution across a broader area, maintaining connection reliability without compromising the thin plate's structural integrity through excessive hole density.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If support member is continuously pressed against first metal member, then stress concentration is reduced, but device complexity increases

Engineering Contradiction:
Improvestress distributionVSAvoidjoining structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The support member is designed to perform multiple functions simultaneously: it provides structural support, distributes stress, prevents out-of-plane deformation, and works in conjunction with adhesive bonding. This multi-functionality reduces the need for additional specialized components, thereby limiting the increase in device complexity while achieving superior stress distribution and reliability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 method significantly increases the joining strength between dissimilar materials by reducing stress concentration and preventing deformation, making the joint more robust and resistant to fractures while maintaining structural rigidity and safety.

Implementation Method 1

The second metal member is continuously or widely pressed against the first metal member by the support member between the welded spots adjacent to each other

Methodology Applied
Scientific EffectMechanical Force: Mechanical Force

Implementation Method 2

the second metal member is bonded to the first metal member by a first adhesive

Methodology Applied
Scientific EffectAdhesive bonding: Adhesive

Implementation Method 3

using techniques like resistance spot welding, laser welding, or arc welding

Methodology Applied
Scientific EffectWelding: Welding

Data Source

PatentEP3578285B1Method for joining dissimilar materials, and dissimilar-material joined body
Publication Date: 2023.11.08 KOBE STEEL LTD
  • EP3578285B1 patent drawingFigure 1~2
  • EP3578285B1 patent drawingFigure 3
  • EP3578285B1 patent drawingFigure 4

AI summary

A steel plate frame 2 and a thin plate 4 are made of different materials. A plurality of through holes 4c are formed in a portion of the thin plate 4 to be placed on the steel plate frame 2. A plurality of projections 6c are formed on a support plate 6, each of the projections 6c being allowed to be inserted into a corresponding one of the through holes 4c. An adhesive 8 is applied to a portion of the steel plate frame 2 on which the thin plate 4 is placed. The thin plate 4 is placed on the steel plate frame 2, and the steel plate frame 2 and the thin plate 4 are bonded together by the adhesive 8. The support plate 6 is placed on the thin plate 4 to insert the projections 6c into the through holes 4c. The projections 6c and the steel plate frame are welded to form a plurality of welded spots 7.