Preload-Indicating Fastener Assembly for Consistent Joint Compression
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Solution Overview
Problem
Variations in frictional forces within fastener joints can lead to inconsistent preloads, causing fatigue in aircraft components over time.
Innovation Solution
A fastening system that includes a fastener assembly with a layer disposed between the fastener assembly and the components, which provides an alert when a predetermined compressive load is reached, ensuring consistent preload achievement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a torque wrench is used to tighten the nut based on existing friction calculations, then the tightening process is simple and quick, but the preload varies due to frictional variations in the threads
Solution Approach 1:
The patent introduces a layer as an intermediary element between the fastener assembly and the components. This layer provides a visual indicator that mediates the relationship between applied torque and achieved preload, allowing operators to see when the predetermined compressive load has been reached, thereby ensuring consistent preload despite friction variations
Solution Approach 2:
The layer acts as a feedback mechanism by providing visual information about the preload status. When the predetermined compressive load is reached, the layer displays an alert signal, giving real-time feedback to the operator to stop tightening, thus achieving precise preload control
2Device complexity
If frictional variations in fastener threads are present, then the fastening process is simpler without additional components, but the preload repeatability deteriorates causing fatigue
Solution Approach 1:
The layer serves as a mediator that interfaces between the fastener assembly and the components. It provides visual feedback about preload achievement without interfering with the fastening mechanism itself, thus maintaining simplicity while improving reliability through better preload control
Solution Approach 2:
The layer utilizes color changes or visual alerts to indicate when the predetermined compressive load has been reached. This visual signal system provides clear, unambiguous feedback about preload status, ensuring consistent and repeatable fastening results
Data Source
AI summary
A fastening system includes a first component and a second component. The fastening system includes a fastener assembly configured to attach together the first component and the second component. The fastening system also includes a layer disposed between the fastener assembly and the first component and/or the second component. The layer is configured to provide an alert when a predetermined compressive load has been reached in the first component and the second component which signals that a preload of the fastener assembly has been reached. A method of preloading a fastener assembly includes applying a torque to the fastener assembly until a predetermined compressive load has been reached in the first component and the second component. The alert of the layer is activated when the predetermined compressive load has been reached which signals that the preload of the fastener assembly has been reached.