Multilayer Thermal Strap Assembly With Friction Stir Welded Interfaces
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Solution Overview
Problem
Existing thermal straps for aeronautic and aerospace applications suffer from material discontinuities at mechanical coupling interfaces, leading to increased thermal resistance and inefficient heat transmission, as well as high procurement costs and time.
Innovation Solution
A method of manufacturing a multilayer thermal strap using a stack of thermally conductive sheets or wires, where the sheets or wires are mutually welded through Friction Stir Welding (FSW) to create a continuous heat path, and thicker thermally conductive straps are used to facilitate the welding process, ensuring strong mechanical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sheets or wires are mutually connected through pressing at mechanical coupling interfaces, then the thermal strap can be assembled and connected to objects, but material discontinuities occur leading to increased thermal resistance
Solution Approach 1:
The patent replaces the mechanical pressing connection system with a friction stir welding system. Instead of using pressing tools to mechanically connect sheets or wires at coupling interfaces, a friction stir welding tool is used to create metallurgical bonds. This substitution eliminates the material discontinuities and thermal resistance associated with mechanical pressing while maintaining the assembly capability of connecting multiple thermal conductive elements.
Solution Approach 2:
The patent changes the connection parameter from mechanical pressing (contact pressure) to friction stir welding (rotational friction heat + mechanical stirring). This parameter change transforms the connection mechanism from a mechanical interface with thermal resistance to a metallurgically bonded interface with continuous heat path, thereby improving heat transmission efficiency while maintaining manufacturability.
2Strength
If screws or clamping bolts are mounted through sheets or wires at mechanical coupling interfaces, then mechanical connection is achieved, but additional thermal resistance is introduced
Solution Approach 1:
The patent replaces the screw or clamping bolt mechanical fastening system with a friction stir welding system. The welding tool creates a forged bond that provides both mechanical strength and thermal continuity, eliminating the need for penetrating fasteners that create thermal barriers. This substitution maintains structural integrity while improving thermal performance.
3Reliability
If friction stir welding is used to join sheets or wires at strip ends, then continuous heat path is achieved, but more complex welding equipment is required
Solution Approach 1:
The patent applies a multi-functional friction stir welding tool that can join both sheets and wires, perform welding at strip ends and at mechanical coupling interfaces, and create both thermal and mechanical bonds simultaneously. This universal tool consolidates multiple functions into one device, making the increased equipment complexity worthwhile by delivering continuous heat paths and eliminating the need for separate mechanical fastening systems.
4Reliability
If procurement of known thermal straps is performed, then thermal straps with mechanical coupling interfaces are obtained, but high costs and time are incurred
Solution Approach 1:
The patent changes the manufacturing approach from procurement of pre-made components to on-demand fabrication using friction stir welding. This parameter change enables custom thermal straps to be manufactured directly at the application site or in-house, eliminating procurement lead times and reducing costs by avoiding commercial markup while maintaining the required thermal and mechanical performance.
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 method enhances heat transmission efficiency by eliminating material discontinuities and maximizing the heat path continuity, while also reducing procurement costs and time through improved manufacturing processes.
Implementation Method 1
mutually welded through Friction Stir Welding (FSW)
Implementation Method 2
the sheets or wires are mutually welded through Friction Stir Welding (FSW) to create a continuous heat path
Data Source
Figure 1~5
Figure 6
Figure 7~8
AI summary
A thermal strap (1) comprises a stack (2) of thermally conductive sheets (3) defining a central portion (4) and a pair of mechanical connection interfaces (5) on opposite sides of the central portion (4) to connect the thermal strap (1) to two objects. The sheets (3) are mutually welded at the mechanical connection interfaces (5) through Friction Stir Welding.