Thermoplastic Composite Riveting Without Resin-Metal Contact
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Solution Overview
Problem
Existing methods for assembling thermoplastic composite parts in aeronautics face challenges due to the difficulty in achieving high mechanical resistance and preventing resin-metal contact, which is critical under high mechanical constraints.
Innovation Solution
The use of thermoplastic riveting with sewing assembly links made of aramid fiber coated with resin, inserted through heated cylindrical bores in thermoplastic parts, ensuring compatibility and high resistance to tearing, and a process involving heated panels for fusion and consolidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal pins or fasteners are used to assemble thermoplastic composite parts, then mechanical strength can be achieved, but resin-metal contact occurs which reduces tear resistance
Solution Approach 1:
The patent applies homogeneity by using thermoplastic material for both the parts being joined and the assembly links. This ensures material compatibility throughout the joint, eliminating resin-metal contact and the associated poor tear resistance. The thermoplastic assembly links are chemically and physically homogeneous with the thermoplastic matrix of the composite parts, creating a unified material system that maintains high tear resistance throughout the entire assembly.
Solution Approach 2:
The patent employs composite materials by using fiber-reinforced thermoplastic assembly links (with aramid, carbon, or glass fibers) to join thermoplastic composite parts. This composite approach provides both the mechanical strength needed for structural applications and the material compatibility required to prevent resin-metal contact, thereby maintaining high tear resistance in the joint.
2Ease of manufacture
If thermoplastic parts are heated above melting temperature and pierced with needles, then assembly can be achieved, but resin-metal contact is promoted which has poor tear resistance
Solution Approach 1:
The patent applies this principle by using disposable heating elements or heating zones that are activated temporarily during the assembly process and then discarded or deactivated. The heating is localized and transient, melting the thermoplastic material only where needed for insertion of the assembly links, without requiring sustained high-temperature exposure that would promote resin-metal contact throughout the entire part.
Solution Approach 2:
The patent utilizes parameter changes by precisely controlling the temperature, time, and spatial distribution of heating during assembly. The thermoplastic material is heated only to the extent and duration necessary to facilitate insertion of assembly links, then rapidly cooled to lock in the joint. This controlled parameter manipulation achieves easy assembly while minimizing resin-metal contact and preserving tear resistance.
3Strength
If ultrasonic vibrations are applied to metal pins in heated composite material, then riveting can be achieved, but resin-metal contact occurs
Solution Approach 1:
The patent replaces the metal pin ultrasonic riveting system with a thermoplastic-based assembly link system. Instead of using metal pins subjected to ultrasonic vibrations, the invention uses thermoplastic assembly links that are inserted into heated zones of the thermoplastic composite parts. This substitution eliminates the metal-component entirely, replacing it with a thermoplastic material that is chemically compatible with the matrix, thereby achieving joint strength without resin-metal contact and preserving tear resistance.
4Stability of the object's composition
If thermoplastic parts are assembled at room temperature, then rigidity is maintained, but significant rigidity prevents effective joining
Solution Approach 1:
The patent applies preliminary action by pre-heating the thermoplastic composite parts at the specific joint zones before inserting the assembly links. This temporary local heating softens the thermoplastic matrix only where needed, allowing the assembly links to be inserted and positioned correctly. After insertion, the part is cooled to restore rigidity and lock in the joint. This preliminary heating action enables effective joining without compromising the overall rigidity of the finished assembly.
Solution Approach 2:
The patent employs local quality by applying heat and allowing material softening only at the specific locations where assembly links are to be inserted, rather than heating the entire part. This localized thermal processing maintains the rigidity and structural integrity of the bulk thermoplastic parts while creating temporary joinability only where needed. The assembly links are inserted into these localized softened zones, and upon cooling, the entire assembly regains its rigidity.
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 provides a strong and reliable joint with high mechanical resistance, avoiding resin-metal contact issues and suitable for high-stress applications like aeronautics, by using thermoplastic resin-based composite material links that are compatible with the parts and reinforced with fibers.
Implementation Method 1
heating needles above the melting temperature of the resin and then piercing the two thermoplastic parts to be assembled
Implementation Method 2
heating the areas of the parts from their opposite faces by the heating panels to a penetration temperature of a drilling tip to initiate the fusion of the areas of the superimposed faces
Implementation Method 3
links being constituted at least in part by a stitching stitch (or tufting) made from thread formed of fiber aramid coated with resin
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to an assembly of zones (10a, 10b) of composite parts (2a, 2b) having a thermoplastic matrix, comprising a plurality of rivet points located along zones (10a, 10b) of the parts, said parts being arranged to overlap one another by stacking two opposing faces (12a, 12b) of the zones (10a, 10b), and each zone (10a, 10b) having another opposite face (11a, 11b) that remains visible with the part (2a, 2b). The riveting is performed with assembly links (6) made from a thermoplastic-resin-based composite material compatible with the material of the parts (2a, 2b). The links (6) are formed at least partially by tufting with a thread made from a material selected from among a fibre coated with aramid resin, a carbon and glass fibre, and said links are embedded in the aforementioned zones (10a, 10b) and extend through same from one side to the other with an angle of between 30° and 90° relative to the faces thereof (11a, 11b; 12a, 12b).