Thermal output coupling characteristics of high-temperature strain gauges

Contact strain measurement is used to study the high-temperature mechanical behavior of materials and components. The measurement precision, which is mainly affected by the thermal output, is very vital in high-temperature strain measurement. By combining experimental analysis with the theories of materials physics, elastic mechanics, thermos-dynamics, mechanical engineering testing technology, and finite element method (FEM), the influence factors of the thermal output error of high-temperature strain gauge were studied, and a compensation model was established, and then a test was conducted to verify the model accuracy and experimental results. In this study, the coupling characteristics of the thermal output of high-temperature strain gauges were investigated based on the thermal expansion theory and the temperature-resistance properties of the material, and the thermal output model of strain gauges was established. Then, the theoretical expression of the heat output under the coupled action of the member, rubber layer, and strain gauge was obtained. Based on the resistor-temperature effects, the electrical conductivities of different wire materials were obtained, and the thermal output property of the grid wire was studied by finite element method. According to the results, two kinds of wire mesh materials were selected as the research object of this paper, and the simulation results were compared with the experimental data, the relative error is less than 7%. Finally, a compensation model of high-temperature strain thermal output was obtained from the theoretical model and experimental results. The results show that the error between the compensation correction and the theoretical value is less than 9%; thus, the error compensation is efficient.