Title page for ETD etd-10262005-100956


Type of Document Dissertation
Author Lin, Shih-Yung
URN etd-10262005-100956
Title Integration and processing of high-resolution moiré-interferometry data
Degree PhD
Department Engineering Mechanics
Advisory Committee
Advisor Name Title
Czanek, R. Committee Chair
Claus, Richard O. Committee Member
Moore, David Michael Committee Member
Morton, John Committee Member
Smith, Charles W. Committee Member
Keywords
  • Moiré method
  • Interferometry
Date of Defense 1992-05-05
Availability restricted
Abstract

A new hybrid method combining moire interferometry, high resolution data-reduction technique, two-dimensional datasmoothing method, and Finite Element Method (FEM) has been successfully developed. This hybrid method has been applied to residual strain analyses of composite panels, strain concentrations around optical fibers embedded in composites, and cruciform composite shear test.

This hybrid method allows moire data to be collected with higher precision and accuracy by digitizing overexposed moire patterns (U & V fields) with appropriate carrier fringes. The resolution of the data is ± 20 nm. The data extracted from the moire patterns are interfaced to an FEM package through an automatic mesh generator. This mesh generator produces a nonuniform FEM mesh by connecting the digitized data points into triangles. The mesh, which uses digitized displacement data as boundary conditions, is then fed to and processed by a commercial FEM package.

Due to the natural scatter of the displacement data digitized from moire patterns, the accuracy of strain values is significantly affected. A modified finite-element model with linear spring elements is introduced so data-smoothing can be done easily in two dimensional space. The results of the data smoothing are controlled by limiting the stretch of those springs to be less than the resolution of the experimental method.

With the full-field hybrid method, the strain contours from moire interferometry can be easily obtained with good accuracy. If the properties of the material are known, the stress patterns can also be obtained. In addition, this method can be used to analyze any two-dimensional displacement data, including the grid method and holography.

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