Quality assessment for strain field determination based on the NISLT approach
Journal
Journal of the Chinese Institute of Engineers
Journal Volume
38
Journal Issue
6
Pages
801-810
Date Issued
2015
Author(s)
Abstract
By determining the state of strain, the status of a structure can be effectively evaluated. Strain field determination based on the non-iterative solution for linear transformations (NISLT) approach has been recently proposed to successfully identify rigid-body motion and natural deformation, which are coupled in the displacement fields in strain calculation. However, the NISLT approach cannot provide a direct measure of the quality of estimated parameters. This study has rigorously derived an analytical expression of the covariance matrix of linear transformation parameters using the NISLT approach. The derivation was used to determine the quality of the displacement field and can be used to estimate the quality of the determined parameters. The derivation was verified in numerical and laboratory experiments, which demonstrated that the estimated maximum principal strains differed from the originally assumed principal strain (real strain) within 1.96 times of the standard deviation (1.96σ). Therefore, the derived quality assessment of the NISLT approach provided a fair estimation of how accurate the strain would be under a certain displacement accuracy. The quality of the structures integrity monitoring system could thus be regulated, which is essential in the planning of structural monitoring tasks.
SDGs
Type
journal article