Thermal Compensation for Strain Gauge Accuracy
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Solution Overview
Problem
Strain gauges mounted to surfaces often detect temperature-related stresses and strains in addition to physical inputs, making it difficult to obtain accurate, real-time data due to the need for extensive post-processing to remove temperature effects, which can negatively impact test plans.
Innovation Solution
A thermally compensating instrumentation system is used, comprising a first sensing system mounted to the component and at least one thermally compensating coupon with non-uniform coefficients of thermal expansion, isolated from mechanical forces, to compensate for temperature effects in real-time, allowing for accurate data collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If strain gauges are mounted to detect stresses and strains, then measurement capability is improved, but temperature-related stresses and strains are also detected making data inaccurate
Solution Approach 1:
The system separates the measurement function into two independent parts: the primary strain gauge system mounted to the component for detecting mechanical stresses and strains, and the thermally compensating coupon system mounted separately to detect only thermal effects. This segmentation allows each subsystem to perform its specific function without interference from the other harmful factors.
Solution Approach 2:
The thermally compensating coupon acts as an intermediary element that measures temperature-related strains separately. By using a coupon made of the same material as the component but isolated from mechanical loads, it serves as a mediator to quantify thermal effects so they can be subtracted from the total measurement, leaving only the mechanical strain component.
2Measurement precision
If post processing is performed to remove temperature effects, then data accuracy is improved, but real-time data acquisition is lost due to time-intensive processing
Solution Approach 1:
The system performs preliminary measurement by having the thermally compensating coupon continuously measure thermal effects in real-time alongside the strain gauge system. Instead of waiting for post-processing to identify and remove temperature effects, the thermal component is measured simultaneously and separately, allowing immediate correction of the strain data without time-intensive retrospective analysis.
Solution Approach 2:
The system establishes a feedback loop where the thermal strain measurements from the compensating coupon are continuously fed back to correct the primary strain gauge readings in real-time. This continuous feedback mechanism allows the system to maintain accurate strain measurements by dynamically compensating for temperature effects as they occur, rather than correcting them after the fact.
3Measurement precision
If thermally compensating coupon is mounted to the component, then temperature compensation is achieved, but device complexity increases
Solution Approach 1:
The system changes the mounting parameters and material properties of the compensating coupon to simplify the overall system. By using a coupon made of the same material as the component and mounting it with mechanically isolating adhesive, the system achieves thermal coupling without mechanical load coupling, automatically providing the correct compensation ratio without complex calibration or adjustment mechanisms.
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 system effectively cancels out up to 92% of thermal effects in real-time, providing accurate and timely strain data, enhancing the reliability of test plans and component monitoring.
Implementation Method 1
The at least one thermally compensating coupon is formed from a second material having non-uniform coefficients of thermal expansion that are substantially identical to the non-uniform coefficients of thermal expansion of the first material
Implementation Method 2
The at least one thermally compensating coupon is connected to the component with a mechanically isolating adhesive
Data Source
AI summary
An instrumentation system for use with a component formed from a first material having non-uniform coefficients of thermal expansion includes a first sensing system configured to be mounted to the component to sense temperature and mechanical forces on the component, and a thermally compensating coupon configured to be mounted to the component adjacent the first sensing system. The thermally compensating coupon is formed from a second material having non-uniform coefficients of thermal expansion that are substantially identical to the non-uniform coefficients of thermal expansion of the first material. A thermally compensating sensing system is mounted to the thermally compensating coupon and connected to the first sensing system. The thermally compensating sensing system is isolated from mechanical forces perceived by the component while sensing temperatures on the component such that the connection of the thermally compensating sensing system to compensate for the temperature sensed by the first sensing system.