Thermoplastic Composite Riveting With Heated Mandrel Hole Expansion
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Solution Overview
Problem
The challenge in connecting aircraft components made of thermoplastic composite materials lies in achieving a robust and crack-resistant joint that can be efficiently processed, considering the difficulties in working with these materials and the need for a method that complements both welded and riveted connections.
Innovation Solution
A method involving the use of a mandrel element to expand pre-drilled boreholes in aircraft components, heating them above their melting point to form a continuous bore for a rivet, which is then inserted to create a strong, thermoplastically bonded connection, allowing for compensation of manufacturing tolerances and prevention of fiber overstretching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a heated mandrel tool is used to create a hole in thermoplastic composite structures, then the hole can be formed with positive fit and material bond, but the process is time-consuming and generates fiber overstretching
Solution Approach 1:
The patent applies preliminary action by pre-drilling holes with a smaller diameter before inserting the mandrel element. This allows the mandrel to subsequently expand the hole to the final diameter while the thermoplastic material is heated, achieving both precise hole formation and faster processing compared to creating the full-size hole directly with a heated tool.
2Weight of moving object
If thermoplastic composite materials are used for aircraft components, then weight is reduced and strength is increased, but the materials become difficult to process with conventional riveting techniques
Solution Approach 1:
The patent applies parameter changes by heating the thermoplastic composite material to its melting temperature or above during the riveting process. This temperature change transforms the material from a rigid, difficult-to-process state to a pliable state that can be easily deformed by the mandrel element, enabling conventional riveting techniques to work effectively with thermoplastic composites while maintaining their weight and strength advantages.
3Ease of manufacture
If rivets are used alone for joining aircraft components, then manufacturing is simpler, but crack propagation in welds cannot be prevented
Solution Approach 1:
The patent merges two joining methods by combining welding and riveting in a hybrid connection. The components are first welded together to create a strong joint, and then rivets are inserted through pre-drilled holes to provide additional reinforcement. This combination leverages the simplicity of welding while adding the crack-prevention capability of rivets, achieving both ease of manufacture and high reliability.
4Manufacturing precision
If pre-drilled boreholes are expanded with a mandrel element while heating above melting point, then fiber overstretching is reduced and manufacturing tolerances are compensated, but additional heating equipment and process steps are required
Solution Approach 1:
The patent merges the heating function and mandrel expansion function into a single integrated process. The mandrel element is inserted through pre-drilled holes while the material is heated to or above its melting temperature, causing the material to deform and bond around the mandrel. This combination achieves precise hole formation with fiber alignment and tolerance compensation without requiring separate heating and expansion equipment, reducing overall system complexity.
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 enables faster and more robust connections with reduced fiber damage, allowing for efficient alignment and secure bonding of aircraft components while preventing crack propagation, and can be used with preassembled components without generating drilling dust.
Implementation Method 1
the first component and the second component are locally heated during expansion so that the first component is thermoplastically deformed when the first bore is widened and the second component is thermoplastically deformed when the second bore is widened
Implementation Method 2
a thermoplastic material is understood to be a material that is solid at common ambient temperatures and can be plastically deformed above a certain temperature. The material-dependent temperature above which the thermoplastic material can be sufficiently plastically deformed for the present application is the melting temperature.
Data Source
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AI summary
A method for joining two aircraft components made of thermoplastic composite material using a rivet is described and claimed. The two aircraft components are positioned section by section, overlapping their surfaces, before bores in both components are expanded with a mandrel element so that, after expansion, the bores form a through-hole for receiving the rivet. During this process, both aircraft components are locally heated by the mandrel element, causing the components to thermoplastically deform as the bores expand. The mandrel element is inserted through the first bore into the second bore. Finally, the rivet is inserted into the through-hole. Furthermore, a system for carrying out the method is described and claimed.