Development of High-Temperature Wire-Grid Thin Film Strain Gauges

Abstract

Aero-engine turbine stator blades are often used in harsh environments with high temperatures and high pressure and are prone to fatigue fractures. Real-time and accurate monitoring of blade surface stress and strain is critical to ensure safe operation. In this study, thin-film strain gauges (TFSGs) that can be used in high-temperature environments above 1000 °C were designed and fabricated using a PtRh6 thin film as the sensitive material. The hysteresis effect of the stress transfer upon establishing a thermo-mechanical coupling finite element model of the Inconel718 high-temperature nickel-based alloy equal-strength beam PtRh6 TFSGs was analyzed and the optimal combination of thin-film thickness and longitudinal grid length of wire-grid TFSGs was determined. In order to solve the problem of high-temperature insulation, the insulating properties of a single-layer Al2O3 insulating film, a single-layer ZrO2 insulating film, a double-layer Al2O3/ZrO2 composite insulating film, and a four-layer Al2O3/ZrO2/Al2O3/ZrO2 composite insulating film at high temperature were compared and studied using scanning electron microscopy to analyze the microscopic morphology and composition of the four insulating film structures. The results showed that the four-layer Al2O3/ZrO2/Al2O3/ZrO2 composite insulating film had the best insulating properties at high temperatures. On this basis, an Al2O3/ZrO2/Al2O3/ZrO2 composite insulating film, PtRh6 sensitive layer, and Al2O3 protective film were sequentially deposited on a high-temperature nickel-based alloy equal-strength beam using DC pulsed magnetron sputtering technology to obtain an Inconel718 high-temperature nickel-based alloy equal-strength beam PtRh6 TFSG. Its gauge factor (GF) and temperature coefficient of resistance (TCR) were calibrated, and the results showed that the sensor could be used in harsh environments of 1000 °C. The above results provide new ideas for measuring stress and strain in aerospace under high-temperature and high-pressure environments.

Calibration Model Optimization for Strain Metrology of Equal Strength Beams Using Deflection Measurements

“…As a high-precision elastic sensitive component, equal strength beams have many advantages, such as good mechanical properties, high accuracy, and simple operation, and are often used in the study and calibration of vibration sensors [ 8 ], displacement sensors [ 9 , 10 ] and strain sensors [ 11 , 12 , 13 , 14 ]. In particular, the metrological calibration of FBG strain sensors with the strain and temperature coupling effects [ 15 ], can be possibly carried out using equal strength beams.…”

All-Three-Dimensionally-Printed AgPd Thick-Film Strain Gauge with a Glass–Ceramic Protective Layer for High-Temperature Applications

“…Real-time monitoring of the surface strain state of aero-engine turbine blades and other structures in high-temperature environments is critical for their ground testing and lifetime prediction. , In the field of high-temperature strain sensing, the conventional options mainly include discrete strain gauges, berth-type resistance strain gauges, and fiber Bragg gratings. − The discrete strain gauges are primarily fixed on the surface of the measured structure through installation or tape, which causes creep errors and interferes with the flow field. − Embedding fiber Bragg gratings into metal structures can adversely impact the structural integrity of the components and increase the risk of damage . Therefore, these strain gauges have struggled to meet the demand for in situ strain monitoring of hot-end components.…”