Methodology for estimating strain gauge measurement biases and uncertainties on isotropic materials

Abstract

Compared to actual strains, the values obtained with strain gauges during experimental measurements contain biases and uncertainties. In this article, we propose a methodology using Monte Carlo simulations to estimate the effects of biases and uncertainties from the following: location uncertainty, integration effect and transverse sensitivity errors in unidirectional strain gauges. Moreover, the specific behaviour of welded gauges is also considered. The approach simulates strain gauges on the displacement fields obtained from the structure’s finite element analyses to predict the expected biases and uncertainties. With the use of experimental measurements designed to highlight the biases between gauge measurements and finite element analyses strain results, we verify the methodology. In our experimental verification, we observe that biases are adequately predicted by the proposed method. It is worth mentioning that such an approach can be used not only for validations between finite element analyses and experimental measurements but also for optimizations of strain gauge positioning during measurement campaigns.