Thermoplastic Bonding for Composite Contour Mismatches
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Solution Overview
Problem
Existing methods for joining composite components are time-consuming and labor-intensive, particularly when dealing with mismatched contours, as they often require multiple steps and can introduce undesirable stresses or increase bondline thickness, affecting the strength of the bond joint.
Innovation Solution
A method involving the use of thermoplastic elements with contoured surfaces to match the mating surfaces of composite components, which are then fused together using heat and compactive pressure to form a structural assembly, thereby accommodating contour mismatches and minimizing bondline thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extra adhesive material is applied to fill gaps between mating surfaces, then the gaps are filled, but the bondline thickness increases which adversely affects the strength properties of the bond joint
Solution Approach 1:
The patent changes the physical state of the bonding material from adhesive (liquid/semi-liquid) to thermoplastic material that can be heated and molded. By controlling the temperature parameter, the thermoplastic material transitions from solid to molten state to fill gaps, then solidifies to form a uniform bondline without excessive thickness, thus maintaining bond joint strength while filling gaps.
Solution Approach 2:
The patent utilizes phase transition of thermoplastic material between solid and molten states. The thermoplastic material is heated to its melting point, becomes molten to flow into and fill gaps between mating surfaces, then is cooled to solidify, forming a uniform bondline with controlled thickness that maintains structural integrity and bond strength.
2Manufacturing precision
If specialized tooling is used to apply high compressive forces to push out gaps, then gaps are eliminated, but manufacturing costs increase and undesirable stresses are induced in the composite components
Solution Approach 1:
The patent replaces the mechanical compression system (specialized tooling applying high compressive forces) with a thermal processing system. Instead of using complex mechanical devices to push out gaps, the thermoplastic material is heated to become molten, naturally flowing to fill gaps under its own weight and minor pressure, then solidifies to eliminate gaps without requiring sophisticated compression tooling.
Solution Approach 2:
The patent changes the bonding process from cold mechanical compression to hot molding. By increasing temperature to melt the thermoplastic material, the process eliminates the need for high compressive forces and specialized tooling, as the molten material naturally conforms to the mating surfaces and fills gaps through fluid flow rather than mechanical pressure.
3Strength
If mechanical fasteners are used to join composite components, then joining is achieved, but the process becomes time-consuming and labor-intensive requiring multiple steps
Solution Approach 1:
The patent merges multiple discrete joining steps into a single integrated process. Instead of separate operations for drilling holes, inserting fasteners, tightening to torque specifications, and inspecting, the thermoplastic bonding process combines gap filling, bonding, and joint formation into one continuous operation where heated thermoplastic material is applied and simultaneously bonded to join components.
Solution Approach 2:
The patent replaces the mechanical fastening system (drilling, fasteners, torque application) with a thermal bonding system. The thermoplastic material, when heated and pressed against the mating surfaces, bonds the components together through melting and solidification, eliminating the need for mechanical fasteners and the multiple steps associated with their installation.
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 approach reduces the time and labor required for joining composite components while improving the strength and durability of the bond joint by eliminating gaps and stress concentrations, enhancing shear and tensile strength.
Implementation Method 1
heating the thermoplastic element to a melting point of the thermoplastic element
Implementation Method 2
applying compactive pressure to the thermoplastic element
Implementation Method 3
cooling the thermoplastic element below a melting point of the thermoplastic element
Implementation Method 4
heating the thermoplastic element to a melting point of the thermoplastic element
Data Source
Figure 1
Figure 2~3
Figure 4A~4H
AI summary
A method of forming a structural assembly may include providing a first component and a second component to be joined together. The method may additionally include scanning a contour of a first mating surface of the first component and scanning a contour of a second mating surface of the second component. The method may further include producing a thermoplastic element having opposing first and second element surfaces substantially matching a contour of the first mating surface and the second mating surface.