MOIRE INTERFEROMETRY WITH EMBEDDED GRIDS, EFFECT OF OPTICAL REFRACTION,
Abstract
Optical refraction resulting from refractive index gradients present in nonhomogeneously stressed models is investigated as a limitation on the usefulness of moire' interferometry employing embedded grids. Estimates of apparent displacements caused by internal refraction are derived for representative static and dynamic problems; Boussinesq's problem, and the problem of a spherically expanding pulse, respectively. Refraction effects are found to be far larger in the dynamic case. Apparatus for dynamic moire' interferometry employing single-spark, high-speed photography is briefly described, and observations of transient motions in Plexiglas models loaded nondestructively by pellet impact are discussed. The moire' results are compared with motion histories obtained using a capacitive transducer. The moire' data exhibit significant anomalies whose basic features agree fairly well with the predicted refraction effects for the aforementioned case of a spherically expanding pulse. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1968
- Accession Number
- AD0669065
Entities
People
- J. S. Whittier
- R. L. Kerber
Organizations
- The Aerospace Corporation