Heated Threaded Fastening for Thermoplastic Composite Joints
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Solution Overview
Problem
Current methods for joining thermoplastic fiber composite components in aircraft construction, such as drilling and self-piercing rivets, face issues like fiber cuttings, delamination, and manufacturing complexity, while thermoplastic welding lacks mechanical strength and requires high pressure and temperature over the entire joining area.
Innovation Solution
A method involving heating at least one thermoplastic fiber composite component to soften it, allowing a fastener with a thread to be inserted without drilling holes, which moves the fibers aside, providing increased strength and avoiding fiber cuttings, and using a fastener with a thread to join components together.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If drilling holes to insert fasteners, then fastening is achieved, but fibers are cut and delamination risk increases
Solution Approach 1:
The patent applies heat to change the physical state of the thermoplastic matrix from solid to softened state, enabling the fastener to be inserted by displacing rather than cutting the fibers. This parameter change (temperature increase) resolves the contradiction by allowing fastening while preserving fiber continuity.
Solution Approach 2:
The patent applies heat treatment before inserting the fastener to soften the thermoplastic matrix in advance. This preliminary action prepares the material to accommodate the fastener without fiber cutting, thereby maintaining fiber continuity and preventing delamination while still achieving fastening.
2Ease of operation
If using self-piercing rivets, then fastening is achieved, but crack formation risk increases and fatigue behavior deteriorates
Solution Approach 1:
The patent uses heat to soften the thermoplastic matrix, changing its mechanical properties from rigid to pliable. This allows the fastener to be inserted by fiber displacement rather than mechanical piercing, eliminating crack formation and preserving fatigue resistance.
3Strength
If thermoplastic welding is used, then joining is achieved, but mechanical behavior is low and high pressure over complete area is required
Solution Approach 1:
The patent applies heat locally only at the fastener insertion point rather than over the complete joining area. This localized heating softens the thermoplastic matrix specifically where needed, allowing thread formation without requiring high pressure over the entire surface, thus reducing device complexity while maintaining joint strength.
Solution Approach 2:
The patent replaces the mechanical welding process (requiring high pressure and temperature over the complete area) with a thermal softening process followed by mechanical thread formation. This substitution eliminates the need for sustained high pressure over the entire joining area while achieving strong mechanical connection.
4Ease of operation
If drilled holes are used for fastening, then fastening is achieved, but manufacturing complexity increases with multiple operations
Solution Approach 1:
The patent combines the heating and fastener insertion operations into a single integrated process. The localized heating softens the thermoplastic matrix just enough to allow immediate fastener insertion, merging what would otherwise be separate operations (heating/softening and fastener installation) into one streamlined manufacturing step.
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 method enhances joint strength, maintains continuous fibers, reduces manufacturing complexity, and is applicable to thermoplastic materials with short fibers and nanoparticles, offering improved stability and efficiency compared to existing techniques.
Implementation Method 1
heating at least a portion of the at least one thermoplastic fiber composite component, and optionally also portions of the other components to be joined, at one or more positions where the components are to be joined
Data Source
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AI summary
Method for joining together different components (11,12) or different sections of a single component (11,12), wherein at least one of the components is a thermoplastic fiber composite component, by using a threaded fastener (13) and by heating at least a portion of the at least one thermoplastic fiber composite component, and by drilling said fastener (13) into the component located at the bottom of the two (12). The disclosure also refers to a joined-together fiber composite component of a vehicle, aircraft or spacecraft, obtainable or obtained by the joining method.