基于响应面法的应变测量精度因子的分析与优化

Analysis and optimization of strain measurement accuracy factor based on response surface method

应变计是诊断结构杆件健康状态的重要传感器,不同应变计其测量精度不同,为研究应变计达到更高测量精度所要求的条件,对应变计敏感栅结构参数及所处的环境温度进行了优化分析。首先,采用有限元计算方法分析了敏感栅栅丝长度、栅丝长宽比以及温度对测量精度的影响;然后,利用design-expert建立了测量精度的响应面模型,并利用评价函数法对响应面模型进行了优化,得到了最优的参数组合;最后,通过格构式杆件的拉压试验进行了优化验证。研究结果表明:敏感栅长宽比存在中间最优值;测量精度不随敏感栅长度的增加而提高;25℃是较佳的测量环境温度;利用评价函数法对响应面模型优化得到了最优参数组合,即L=4 mm,H=2 mm,T=25℃,通过试验验证了优化后的参数组合较优化前使应变计的测量精度有了明显的提高,较优化前提高了3.760%。对建立的应变计测量精度响应面进行优化,可明显降低所研究因子的叠加效应对应变计造成的测量误差,该研究方法为应变计的设计与选择提供了有效依据。

The strain gauge is a critical sensor for diagnosing the health state of structural members,different strain gauges have different measurement accuracy.In order to study the conditions required for the strain gage to achieve higher measurement accuracy,the structural parameters of the sensitive gate of the strain gage and the ambient temperature were optimized.Firstly,the finite element calculation method was used to analyze the effects of sensitive grid length,aspect ratio and temperature on the measurement accuracy.Secondly,design-expert was used to establish a response surface model with measurement accuracy.The evaluation function method was used to optimize the response surface model to obtain the optimal parameter combination.Finally,the optimization was verified by the tensile and compression test of lattice members.The results of the study show that,there is an intermediate optimal value for the aspect ratio of the sensitive gate.The measurement accuracy does not improve with the increase of the length of the sensitive gate.25 ℃ is the best ambient temperature for measurement.The optimal parameter combination obtained by the evaluation function method is used to optimize the response surface model,that is,L=4 mm,H=2 mm,T=25 ℃,and the measured accuracy of the strain gauge is significantly improved by 3.760% compared with that before optimization.Optimizing the response surface of the measured accuracy of the established strain gauge can significantly reduce the measurement error caused by the superposition effect of the studied factors on the strain gage.The research method provides an effective basis for the design and selection of strain gages.