Full-Field Strain Shape Estimation from 3D SLDV

Abstract

The ability to measure full-field strains is desirable for analytical model validation or characterization of test articles for which there is no model. Of further interest is the ability to determine if a given environmental test’s boundary conditions are suitable to replicate the strain fields the test article undergoes in service. In this work, full-field strain shapes are estimated using a 3D scanning laser Doppler vibrometer and several post-processing methods. The processing methods are categorized in two groups: direct or transformation. Direct methods compute strain fields with only spatial filtering applied to the measurements. Transformation methods utilize SEREP shape expansion/smoothing of the measurements in conjunction with a finite element model. Both methods are used with mode shapes as well as operational deflection shapes. A comparison of each method is presented. It was found that performing a SEREP expansion of the mode shapes and post-processing to estimate strain fields was very effective, while directly measuring strains from ODS or modes was highly subject to noise and filtering effects.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA-0003525.

This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the paper do not necessarily represent the views of the U.S. Department of Energy or the United States Government.