Research On Optimization Of Sensitive Grid Structure And Coating Process Parameters Of High Temperature Strain Gauge

In the harsh working environment,the failure of hot-end components of aero-engine is frequent.As a support condition of research,high temperature strain measurement technology is closely related to aero-engine,especially in the study of mechanical behavior and service life of hot-end components,high temperature strain measurement is a very important and effective way.At present,precise measurement of structural strain by high temperature strain gauge is an urgent problem to be solved.In order to improve the measuring accuracy of the strain gauge,the finite element model of high-temperature strain gauge was established in this paper.The influence of sensitive grid structure parameters and coating process parameters on the measuring accuracy was studied by finite element method.A new dimensionless structure parameter called transverse effect length ratio was proposed,and the function relation between measurement error and transverse effect length ratio was established,and the parameter optimization formula was derived based on the function relation.Aiming at high measuring precision,the Response Surface Method was used to optimize the grid length,grid spacing and grid bending number based on Design Expert software.The study show that the smaller the wire diameter is,the smaller the measurement error is.There is an intermediate optimal value for the length,spacing,bending number and length-width ratio of the grid wire to minimize the measurement error.The relationship between the measurement error and the transverse effect length ratio is a piecewise linear function.The measurement error of the structure parameters of the given sensitive gate can be quickly estimated by using the relational expression,and the relative error of the estimated result is less than 10%.The measurement error of the parameter combination designed by the optimization formula does not exceed 0.10%.When the thickness of the transition layer,the basement and the covering layer increases,the steady-state heat output of the strain gauge decreases.When the linear expansion coefficient of the transition layer and the basement increases,the steady-state heat output of the strain gauge increases.Among the parameters of sensitive grid structure,the influences on the measurement accuracy are grid wire length,grid wire spacing and grid wire bending number successively.The parameters that contribute to the highest measurement precision are:diameter of 0.02mm,length of 8.80mm,spacing of 0.42mm,and bending number of 5.This study provides an effective method for the selection and parameter optimization of the strain gauge,and also provides a reference for the error analysis of the strain gauge.