Multi-Layer Bonded Joint Structure for Dissimilar Materials
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Solution Overview
Problem
The bonding between members made of different materials, such as fiber reinforced plastic and titanium alloy, experiences a decrease in strength due to cracks generated by the difference in deformation between the members, leading to reduced fatigue strength.
Innovation Solution
A joint structure is designed with a fit-in groove and an insertion section, featuring multiple bonding layers of varying hardness, where softer layers allow for greater deformation and are strategically positioned to suppress crack occurrence, and fiber-containing layers with different orientations to enhance bonding strength and absorb vibrations and impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If members made of different materials (e.g., fiber reinforced plastic and titanium alloy) are bonded together, then the joint structure achieves multi-material assembly, but the bonding strength decreases due to cracks generated by deformation difference
Solution Approach 1:
The patent applies local quality by creating bonding layers with different hardness values at different locations between the members. The softer bonding layer is positioned at the interface where deformation occurs, allowing it to accommodate the deformation difference between dissimilar materials and prevent crack propagation, while maintaining overall bonding strength.
Solution Approach 2:
The patent uses composite materials by combining multiple bonding layers with different hardness properties between the fiber reinforced plastic and titanium alloy members. This multi-layer composite bonding structure allows each layer to perform its specific function: the softer layer absorbs deformation while the harder layer provides structural support.
2Device complexity
If a single bonding layer is used between different materials, then the structure is simple, but crack formation occurs due to deformation mismatch
Solution Approach 1:
The patent segments the bonding interface into multiple bonding layers with different hardness values. This segmentation allows each layer to independently manage the deformation stresses, with the softer layer accommodating dimensional changes and preventing cracks from propagating through the entire bonding interface, thereby improving fatigue strength.
Solution Approach 2:
The softer bonding layer acts as a cushion that is positioned in advance between the dissimilar materials. This softer layer anticipates and absorbs the deformation differences before they can cause crack formation, providing protective cushioning against the harmful effects of thermal and mechanical expansion mismatches.
3Strength
If the bonding layer is made hard to increase strength, then bonding strength improves, but crack formation increases due to inability to accommodate deformation
Solution Approach 1:
The patent applies local quality by creating bonding layers with different hardness values at different locations between the members. The softer bonding layer is positioned at the interface where deformation occurs, allowing it to accommodate the deformation difference between dissimilar materials and prevent crack propagation, while maintaining overall bonding strength.
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 solution effectively suppresses the decrease in strength and fatigue by reducing crack formation and ensuring sufficient bonding strength, while allowing for necessary deformation and impact absorption.
Implementation Method 1
softer layers allow for greater deformation and are strategically positioned to suppress crack occurrence
Implementation Method 2
fiber-containing layers with different orientations to enhance bonding strength and absorb vibrations and impacts
Data Source
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Figure 5~6
AI summary
A joint structure (100) includes a first member (110) having a fit-in groove (116), a second member (120) made of a material different from a material of the first member (110) and having an insertion section (124) to be inserted into the fit-in groove (116), and a plurality of bonding layers having different hardness and formed between the fit-in groove (116) and the insertion section (124).