Spigot Fastener Strain Gauge Mounting for Thrust Measurement
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Solution Overview
Problem
Conventional spigot fasteners in aircraft engines face challenges in accurately measuring thrust forces due to the difficulty in mounting strain gauges, as the shaft's movement along the axis makes it hard to maintain a constant length, which is necessary for precise force measurement.
Innovation Solution
A new structural form for the spigot fastener is introduced, featuring an intermediary part between the shaft and the recess, maintaining constant or slightly varying length, allowing for accurate force measurement along two orthogonal axes by equipping strain gauges on the parts, with a shaft and flange configuration where the shaft's rigidity is greater than the flange's, enabling force transmission and measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the shaft moves freely along the axis to absorb thrust force, then the thrust force can be effectively absorbed, but the length of strain varies making it difficult to measure the thrust force accurately
Solution Approach 1:
The spigot fastener is divided into multiple parts: a first part (shaft) that moves to absorb thrust, a second part (intermediary element with flange) that maintains constant strain length, and a third part (recess) that provides measurement capability. This segmentation allows different parts to fulfill different functions - the shaft absorbs thrust while the flange maintains measurement accuracy.
Solution Approach 2:
The second part (intermediary element with flange) acts as a mediator between the moving shaft and the fixed recess. It transmits the thrust force from the shaft to the recess while maintaining a constant length for strain measurement, thus resolving the contradiction between movement and measurement accuracy.
2Device complexity
If the spigot fastener uses a simple shaft-recess configuration, then the structure is simple, but it cannot accommodate measurement devices while maintaining functionality
Solution Approach 1:
The spigot fastener is segmented into three functional parts: the first part (shaft) for thrust absorption, the second part (intermediary element with flange) for measurement, and the third part (recess) for structural support. This segmentation enables measurement capability while maintaining structural efficiency.
Solution Approach 2:
The second part (intermediary element) serves multiple functions: it connects the shaft to the recess, maintains constant strain length for accurate measurement, transmits thrust force, and provides a stable mounting surface for strain gauges. This multi-functionality adds measurement capability without significantly increasing overall 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 design allows for precise measurement of thrust forces along the OX and OZ axes, enhancing the accuracy of force measurement and ensuring the fastener's security, while minimizing fuel consumption costs by optimizing force transmission in aircraft engines.
Implementation Method 1
strain gauges to measure force generated by the engine while operating
Data Source
AI summary
A spigot-type fastener for an aircraft is to be interposed between the structure of the aircraft and an attachment structure of the aircraft engine. The fastener is to absorb the force generated by the engine along two orthogonal axes. The fastener includes a first part, a second part, a third part, and one or more strain gauges. One end of the first part is secured to the second part. One end of the second part is separated from the first part by a clearance. The opposite end of the second part fits into a recess of the third part via a protrusion, such that the force along both axes is transmitted by the first part to the third part by the second part.