Aircraft Interdiffusion Joining for Thermoplastic-Thermoset Bonds
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Solution Overview
Problem
Conventional joining methods for fiber-reinforced components in aviation are inefficient and unsuitable for all material pairings, often resulting in high manufacturing costs and inadequate load properties under inhomogeneous loads, particularly due to the generation of homogeneous connections that can lead to local stress increases.
Innovation Solution
A multi-material interdiffusion joining method using additive manufacturing to create a connecting region with varying thermoplastic polymer materials and surface structures, allowing for the formation of an interdiffusion layer between fiber-reinforced components with different polymer matrices, enabling adaptation to specific load scenarios and enhancing load capacity and damage tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional joining methods (riveting, adhesive bonding, welding) are used to join fiber-reinforced components, then the components can be connected, but the manufacturing outlay becomes high and the load properties are inadequate under inhomogeneous loads
Solution Approach 1:
The patent applies parameter changes by transitioning from conventional joining methods to film-based interdiffusion joining (FIDJ), which uses thermal energy and pressure parameters to create interdiffusion layers. This changes the fundamental parameters of the joining process, achieving superior load properties under inhomogeneous loads while maintaining manufacturing feasibility through controlled thermal and pressure application.
Solution Approach 2:
The patent employs composite materials by using a film composed of thermoplastic matrix and reinforcing fibers (such as aramid or carbon fibers) as the joining medium. This composite film structure enables the connection to exhibit enhanced mechanical properties and adapt to inhomogeneous loading conditions, resolving the contradiction between reliability and manufacturing complexity.
2Ease of manufacture
If homogeneous connections are created using conventional methods, then the joining process is simple, but local stress increases occur leading to reduced damage tolerance
Solution Approach 1:
The patent applies local quality by creating a non-homogeneous connection structure through FIDJ, where the interdiffusion layer has varying properties across its thickness and area. The film thickness, fiber orientation, and interdiffusion extent are locally optimized to distribute stresses evenly and prevent stress concentration, thereby enhancing damage tolerance while maintaining a relatively simple joining process.
3Adaptability or versatility
If adhesive bonding or welding is used to adapt connections to specific material pairings and functions, then the connection can be tailored, but the manufacturing complexity increases
Solution Approach 1:
The patent applies universality by developing a FIDJ process that can be used across multiple material pairings (thermoplastic-thermoplastic, thermoplastic-thermoset, thermoplastic-metal) and various functional requirements. The same basic FIDJ methodology adapts to different materials and loading conditions through parameter adjustment, providing versatile connection solutions without proportionally increasing manufacturing 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
The method improves load properties and reduces manufacturing outlay by creating connections tailored to expected loads, increasing load capacity and damage tolerance while minimizing structural weight and manufacturing complexity, avoiding issues like 'kissing bonds' and local stress increases.
Implementation Method 1
supplying heat in order to fix the connecting region to the second component, preferably with formation of an interdiffusion layer in order to join the first component to the second component
Implementation Method 2
supplying heat in order to fix the connecting region to the second component
Implementation Method 3
forming a connecting region on the first component in order to generate a joining surface on the first component, the connecting region comprising one or more thermoplastic polymer materials
Data Source
AI summary
A joining method and assembly for an aircraft. To improve the characteristics or permit hitherto impossible connections between thermoplastic and thermoset components, a multi-material joining method is disclosed in which a thermoplastic connecting region is formed on the thermoplastic component. The connecting region is connected to the thermoset component by interdiffusion. For this purpose, the uncured second component is brought into contact with the connecting region and heat is supplied. An interdiffusion layer is formed which fixedly connects the second component and the connecting region to one another and thus joins the first component to the second component.