Threaded Flanged Bushing for Composite-Metal Fastening
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Solution Overview
Problem
Fastening composite materials to metals with different thermal expansion coefficients poses challenges due to thermal stresses and mechanical strain on fasteners and surrounding materials, as existing solutions fail to effectively distribute loads and manage thermal disparities.
Innovation Solution
A fastening system comprising a low-profile, internally threaded bushing with a flange and a threaded bolt, where the bushing is inserted into a hole of one material and the bolt passes through a coaxial hole in another material, securing them flush together, with optional features like stakes and thread-locking rings for enhanced stability and prevention of rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If composite materials are fastened to metals with significantly different coefficients of thermal expansion, then the joined structure achieves high strength-to-weight ratio and temperature resistance, but thermal stresses mechanically strain the fasteners and surrounding composite material
Solution Approach 1:
The patent introduces a bushing as an intermediary component between the composite material and metal fastener. The bushing is inserted into a hole in the composite material and provides a metal interface for the fastener to engage with. This mediator allows the fastener system to achieve the necessary mechanical strength while isolating the composite material from direct thermal stress concentration at the fastener interface, thereby resolving the contradiction between strength requirements and thermal stress management.
2Reliability
If a bushing is used to distribute load in composite materials, then load distribution improves, but the bushing adds device complexity
Solution Approach 1:
The patent combines multiple functions into a single integrated bushing component. The bushing simultaneously provides load distribution across the composite material, creates a threaded engagement interface for the fastener, and acts as a thermal stress management interface. By merging these functions into one component rather than using separate elements, the solution achieves improved load distribution while minimizing the increase in device complexity.
Data Source
AI summary
A fastening system includes a first material having a first hole, a second material having a second hole, a bushing, and a threaded bolt. The bushing is located in the second hole and has a first end abutting the first material and a flanged second for securing the bushing to the second material. A threaded bolt extends through the first hole and into the bushing to secure the first material flush against the second material.