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Finite strain analysis by image processing: smoothing techniques
Author(s) -
Amodio D.,
Broggiato G.B.,
Salvini P.
Publication year - 1995
Publication title -
strain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.477
H-Index - 47
eISSN - 1475-1305
pISSN - 0039-2103
DOI - 10.1111/j.1475-1305.1995.tb00979.x
Subject(s) - smoothing , image processing , digital image correlation , infinitesimal strain theory , computer science , computation , digital image processing , stereoscopy , field (mathematics) , finite element method , set (abstract data type) , data processing , algorithm , noise (video) , computer vision , image (mathematics) , mathematics , structural engineering , engineering , optics , physics , pure mathematics , programming language , operating system
This paper is concerned with a methodology for measuring large strain fields based on digital image processing and numerical computations. The facility, already described in a previous paper by the authors, is based on a stereoscopic‐procedure, which returns the locations of a dot grid, previously etched on the surface of the work piece, in a three dimensional space. The markers are acquired by two CCD cameras from two different viewpoints. The data are then processed by a procedure based on shape function analysis. Tlie strain field is described by a plane Lagrangian referential co‐ordinate system, so that it is possible to take into account large displacements and finite rotations. Thus, the definition of a strain tensor on a 3‐D surface is widely discussed. The present paper faces the question of the noise propagation through the post‐processing algorithm. The method proposed is able to supply the confidence limits of the returned measurements. The strain analysis procedure was tested by a numerical input. A set of data were simulated, as returned by the acquisition system, for a specific strain problem. In this way the statistical parameters of the data can be easily controlled to explore a wide surrounding of cases. The complete post‐processing procedure was then applied to an experimental case concerning a high strain tensile test.