Showing papers by "K. Ramesh published in 2006"
TL;DR: In this paper, a comparative study has been conducted on the performance of these methods both qualitatively and quantitatively, and theoretically simulated and experimentally recorded images for a ring under diametral compression is used.
Abstract: With the advent of PC-based digital image processing systems, automation of parameter estimation based on intensity processing from the entire field has now become simpler. Various methods for obtaining the isoclinic parameter using plane, circular, and mixed polariscopes have been reported in the literature. A comparative study has been conducted on the performance of these methods both qualitatively and quantitatively. The focus of the study is on how these algorithms provide the basic isoclinic data. To illustrate the performance, theoretically simulated and experimentally recorded images for a ring under diametral compression is used. The role of background light intensity and quarter-wave plate mismatch on the experimental evaluation of isoclinic data is brought out.
25 citations
TL;DR: In this article, a novel approach to plot photoelastic fringe contours from 3D finite element results is presented, which uses a scanning approach and the evaluation of total fringe order is achieved by combining a file structure and subsequent sorting of these data to enable integration along the light path.
Abstract: A novel approach to plot photoelastic fringe contours from three-dimensional finite element results is presented. Plotting of fringe contours from 3D FE models requires the calculation of secondary principal stresses along the light path. The definition of secondary principal stresses and the calculation of relevant photoelastic data for fringe plotting are discussed. The plotting scheme uses a scanning approach and the evaluation of total fringe order is achieved by combining a file structure and subsequent sorting of these data to enable integration along the light path. The methodology is validated for the problem of a cantilever beam with an edge load. The usefulness of the methodology to verify 3D FE modelling and for experimentalists to design their experiments is indicated. Copyright © 2006 John Wiley & Sons, Ltd.
19 citations
TL;DR: In this paper, a new method is developed, which uses a dark field image for ambiguous zone identification and its correction, and the performance of the new methodology is demonstrated by using the problem of a ring under diametral compression and a slice cut from a stress frozen model.
Abstract: Phasemaps obtained by phase shifting techniques in digital photoelasticity contain ambiguous zones. To obtain total fringe order by phase unwrapping, the phasemap should be free of ambiguous zones. A new method is developed, which uses a dark field image for ambiguous zone identification and its correction. This methodology is explained and validated by solving a benchmark problem. As ambiguous zones are of arbitrary shape, an advanced boundary extraction method developed in-house is used for effecting the correction in practical problems. The performance of the new methodology is demonstrated by using the problem of a ring under diametral compression and a slice cut from a stress frozen model.
17 citations
TL;DR: In this paper, a new digital photoelastic method based on phase shifting using monochromatic light source is presented It provides full field values of isoclinics (θ) and isochromatics (N) in a true sense among the several methods available for data acquisition, phase shifting / polarization stepping techniques are most widely used for their simplicity and accuracy
Abstract: Photoelasticity is one of the most widely used techniques for experimental stress and strain analysis With the availability of low cost digital image processing systems, a separate branch of photoelasticity known as digital photoelasticity came into existence providing whole-field values of the isoclinics (θ) and isochromatics (N) in a true sense Among the several methods available for data acquisition, phase shifting / polarization stepping techniques are most widely used for their simplicity and accuracy In this paper a new digital photoelastic method based on phase shifting using monochromatic light source is presented It provides full field values of θ and N The arrangement is carefully chosen with the intention of reducing the influence of quarter wave mismatch error in the evaluation of θ and N The methodology is validated for the benchmark problem of a disk under diametral compression
9 citations