Whole-field strain measurement in a pin-loaded plate by electronic speckle pattern interferometry and the finite element method

Abstract

ABSTRACT--The strain field in an epoxy plate loaded in tension through a steel pin is determined using electronic speckle pattern interferometry (ESPI) and the finite element method (FEM). In a dual-beam illumination speckle interferometer, the in-plane component of the displacement at the plate's surface is accurately measured using a tour-step phase-shifting algorithm. Digital image processing algorithms have been developed for noise reduction and strain calculation directly in the computer from the phase map with a strain gage length of about 0.4 mm. A whole-field strain map is obtained, as well as distributions of strain concentration factor, in critical regions near the hore of the plate. FEM is used to perform a nonlinear contact analysis accounting for friction effects at the pinhole interface. The agreement between experimental results and numerical predictions is good. In terms of speed, accuracy and ease of use, dual-beam ESPI appears to be a superior method of whole-field strain analysis.

Follow-up of a panel restoration procedure through image correlation and finite element modeling

“…This method has been used for a long time, and more recently, it has been used in conjunction with field measurements in Schajer and Steinzig (2005), Nelson et al (2006) and Baldi (2007) and with finite elements for analyzing the measures, with or without inverse identification, see (Zhang et al, 1997;Shaw and Chen, 1990;Schajer, 2009;Lanza di Scalea et al, 1998;Cárdenas-Garcí a and Preidikman, 2006). Since residual stresses are self-balanced on the considered structure, their energy is null on any displacement change on the same structure.…”

Application of digital image cross-correlation and smoothing function to the diagnosis of breast cancer

“…Recently, elastography has emerged as a method to detect or classify pathological tissues (Hall, 2003;Lanza di Scalea et al, 1998;Ophir et al, 2002Ophir et al, , 1999Ophir et al, , 1996. This imaging modality intends to detect the difference of the stiffness by applying the principle of palpation to US signals.…”

Measurement of Deformation by Means of Correlation of Speckle Fields

“…Speckle photography requires that the measured displacement exceeds the size of the speckles themselves, while speckle interferometry requires that the opposite condition is fulfilled, i.e., the displacement is smaller than the speckle size. The mentioned methods have achieved intense progress during last decades in consequence of development of modern optoelectronic components and converted to their electronic or digital modification [7][8][9].…”