Composite Frame Joints With Shell Couplers for Reliable Load Transfer
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Solution Overview
Problem
Challenges exist in creating structurally reliable and cost-efficient joints for fiber-reinforced polymer-matrix composite frames, particularly in connecting optics equipment to composite frames and larger structural systems, due to weak strength properties, manufacturing limitations, and limited applicability of traditional joining methods.
Innovation Solution
The development of composite frame joints using upper and lower shells with grooves and depressions that accommodate composite rods, joined together to form X-, T-, K-, and L-type connections, allowing effective load transfer and integration with opto-mechanical equipment and larger structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional metallic joining solutions (welding, rivets, bolting) are used to connect composite rods, then connection strength may be improved, but applicability is limited and manufacturing complexity increases
Solution Approach 1:
The patent introduces an intermediate coupling device that mediates between composite rods and external structures. This coupling device includes a first portion that interfaces with the composite rod through mechanical interlocking (recesses and protrusions) and a second portion that provides standardized external connection interfaces, thereby enabling traditional metallic joining methods to be applied indirectly without directly joining composite rods
Solution Approach 2:
The coupling device is segmented into distinct functional portions: a first portion for interfacing with the composite rod structure and a second portion for external connections. This segmentation allows each portion to be optimized for its specific function, improving overall adaptability while maintaining connection strength
2Ease of manufacture
If adhesive-based complex joint geometries are used to connect composite rods, then manufacturing complexity is reduced, but structural behavior and strength properties deteriorate
Solution Approach 1:
The coupling device segments the joining function into mechanical interlocking components rather than relying on complex adhesive geometries. The recesses and protrusions provide straightforward mechanical attachment that is easier to manufacture while delivering superior structural performance
Solution Approach 2:
The coupling device appears to utilize composite material construction that combines mechanical interlocking features with material-level bonding, creating a hybrid joining approach that achieves both manufacturing simplicity and high structural strength
3Weight of moving object
If composite frames are designed with interconnected composite rods, then weight is reduced, but joint reliability and structural integrity worsen
Solution Approach 1:
The coupling device serves as a reliable intermediary that bridges composite rod connections, providing robust mechanical interlocking through recesses and protrusions. This intermediate element compensates for the inherent weakness of direct composite-to-composite joints while maintaining the lightweight composite frame architecture
Solution Approach 2:
The coupling device incorporates built-in redundancy and load distribution features that cushion against potential joint failures. The mechanical interlocking design with multiple contact points provides fail-safe characteristics that enhance overall joint reliability before failures can occur
Data Source
Figure 1~2A
Figure 2B~2D
Figure 3A~3D
AI summary
A joint for a composite frame includes a first composite rod (104A), a first shell (142) abutting the first composite rod, a second shell (144) abutting the first composite rod and disposed opposite the first shell relative to the first composite rod. The first and second shells are joined together such that composite rod is fixed therebetween. A method of forming joints of composite frame includes forming a composite frame by interconnecting a plurality of composite rods formed by an Automated Fiber Placement (AFP) manufacturing method around a mandrel, applying a first shell to the plurality of composite rods at a first location where composite rods are interconnected, applying a second shell at the first location opposite the first shell relative to the composite rods, and joining the first and second shells together with the composite rods at the first location disposed between the first and second shells.