Strain Sensor Platform With Groove For Rotating Shaft
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Solution Overview
Problem
Existing methods for attaching strain sensing elements to substrates, such as increasing the substrate size, lead to increased material and weight requirements while failing to effectively reduce strain transfer during operation, especially on rotating shafts, causing bending effects and measurement errors.
Innovation Solution
A method involving machining a circular flat with a channel around it on the substrate surface, where the channel's depth and width are optimized to dilute strain, maintaining structural integrity and ensuring the sensor operates within its optimal range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate size is increased to reduce strain transfer to the sensor, then the strain transfer is reduced, but the material requirements and weight of the substrate increase
Solution Approach 1:
The substrate surface is segmented into distinct regions: a platform area for sensor mounting and a channel (groove) area surrounding it. This segmentation allows the channel to act as a strain-isolating feature that reduces strain transfer to the sensor without requiring overall substrate size increase, thereby reducing material usage and weight while maintaining reliability
Solution Approach 2:
The channel (groove) acts as an intermediary structural feature between the substrate and the sensor platform. It serves as a strain-breaking element that interrupts strain pathways, reducing strain transfer to the sensor without requiring the entire substrate to be larger, thus achieving reliability improvement without proportional weight increase
2Reliability
If the substrate size is increased to reduce strain transfer to the sensor, then the strain transfer is reduced, but the space required to accommodate the substrate increases
Solution Approach 1:
The substrate surface is segmented into distinct regions: a platform area for sensor mounting and a channel (groove) area surrounding it. This segmentation allows the channel to act as a strain-isolating feature that reduces strain transfer to the sensor without requiring overall substrate size increase, thereby reducing material usage and weight while maintaining reliability
Solution Approach 2:
Instead of reducing strain transfer by increasing the lateral dimensions (area) of the substrate, the invention introduces a dimensional feature (channel/groove) that utilizes the depth dimension. This allows strain isolation to be achieved through vertical geometry rather than horizontal expansion, maintaining compact substrate area while improving reliability
3Stress or pressure
If a ring shaped groove is cut around the measuring area to reduce intrinsic stresses, then the intrinsic stresses are reduced, but bending effects are caused which result in errors in measured readings
Solution Approach 1:
The channel (groove) is positioned specifically in the circumferential region surrounding the platform, creating local strain relief exactly where needed at the sensor-substrate interface. This localized approach reduces intrinsic stresses at the measurement point without introducing global bending effects that would compromise measurement precision across the entire substrate
Solution Approach 2:
The channel is machined into the substrate in advance of sensor installation, pre-establishing the strain-relief geometry before the sensor is mounted. This preliminary action ensures that when the sensor is installed on the platform, the intrinsic stresses have already been relieved by the channel, preventing measurement errors while maintaining measurement precision
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A circular shaft (1) has a platform (2) formed thereon by machining a circular flat into the surface of the shaft (1). A channel (3) extends around the periphery of the circular flat (2) with a depth in the range of 10 to 15 % of the diameter of the shaft and in the range of 30 to 50 % of the width / diameter of the platform. The width of the platform is (4) to 7 % of the diameter of the shaft. A sensor is mounted on the platform (2), the formation of the platform and surrounding channel reducing the strain arising in the device which is transferred to the sensor.