Electroactive Polymer Rivets for Fast Composite Airframe Joining
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Solution Overview
Problem
The riveting process for joining primary parts in composite airframes is time-consuming, noisy, and hinders weight reduction, while maintaining high redundancy and safety.
Innovation Solution
A method using electroactive polymer (EAP) fasteners that involve forming openings in fiber composite parts, exposing fibers, and activating/deactivating the fastener to engage and disengage with the fibers for flush connections, eliminating the need for traditional rivets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional riveting is used to join fiber composite parts, then high safety and high redundancy are achieved, but the process becomes time-consuming and prevents weight reduction
Solution Approach 1:
The patent replaces traditional mechanical riveting systems with electroactive polymer (EAP) fasteners that use electrical activation to change shape. The EAP material transforms from a contracted state during insertion to an expanded state for fastening, eliminating the need for complex mechanical riveting tools and multiple rows of fasteners, thereby reducing processing time while maintaining connection reliability
Solution Approach 2:
The patent utilizes parameter changes in the electroactive polymer material by applying electrical voltage to trigger phase transformation. The EAP fastener transitions between contracted and expanded states through electrical activation, enabling rapid deployment and engagement without mechanical tooling, thus improving productivity while maintaining the structural integrity required for safety
2Reliability
If traditional riveting is used to join fiber composite parts, then high safety and high redundancy are achieved, but weight reduction is prevented
Solution Approach 1:
The patent replaces heavy traditional metal rivets with lightweight electroactive polymer fasteners. The EAP material inherently provides sufficient fastening force through its expansion mechanism, and the design allows for fewer fasteners per joint, significantly reducing the overall weight of the airframe while maintaining the high safety standards required for primary structural connections
Solution Approach 2:
The patent employs electroactive polymer composite materials that combine electrical responsiveness with mechanical fastening functionality. These composite EAP fasteners offer a high strength-to-weight ratio compared to traditional metal rivets, enabling weight reduction in the airframe structure while preserving the reliability and redundancy necessary for primary part connections
3Reliability
If traditional riveting is used to join fiber composite parts, then high safety is achieved, but noise is generated
Solution Approach 1:
The patent replaces the noisy mechanical impact and friction of traditional riveting with a quiet electrical activation process. The EAP fasteners are inserted in a contracted state and then activated electrically to expand and engage with the surrounding material, eliminating the loud mechanical impacts and friction noises characteristic of conventional riveting operations while maintaining secure fastening
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
Provides fast, quiet, and lightweight fastening with high out-of-plane shear transfer, suitable for automated processes, reducing tool usage and enabling aerodynamic and acoustic benefits.
Implementation Method 1
activating a fastener, that includes electroactive polymer material, so as to reduce a diameter of the fastener and inserting the activated fastener into the opening; deactivating the fastener inside the opening so that the diameter of the fastener increases
Implementation Method 2
removing matrix material from the inner circumferential surface so as to expose the fibers; the matrix material is evaporated by electromagnetic radiation, preferably laser radiation
Data Source
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AI summary
In order to improve fastening of structural parts to each other that are usually riveted, the invention proposes a fastener (36) that includes electroactive polymer material. The parts (10, 12) have an opening within an inner circumferential surface. Fibers (16) protrude from the inner circumferential surface into the opening and interlock with chains of micrograins of the electroactive polymer material.