K. Ramesh

Bio: K. Ramesh is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Photoelasticity & Stress intensity factor. The author has an hindex of 23, co-authored 125 publications receiving 1884 citations. Previous affiliations of K. Ramesh include Indian Institute of Technology Bombay & Indian Institutes of Technology.

Analysis of Stress Distribution in Dry Masonry Walls Using Three Fringe Photoelasticity

Abstract: Masonry being a composite system is very complex to study with analytical methods alone. Quantitative digital photoelastic analysis using Three Fringe Photoelasticity (TFP) is carried out on a model of a dry masonry wall with bricks made up of epoxy, loaded with a concentrated load. The result obtained provides insight into the micromechanics of force transmission and interactions between bricks in masonry. The result shows that force transmission through the wall occurs at discrete points. A tree like hierarchical pattern of stress flow is observed. It is also observed that the stress percolation results in the existence of stress-free zones in the model domain.

Noise-Free Determination of Isochromatic Parameter of Stereolithography-Built Models

Abstract: Recently, stereolithography, one of the rapid prototyping (RP) techniques, has simplified the process of making three-dimensional (3-D) photoelastic models. One of the issues in stereolithography-made models is the noise due to porosity of the model. This is undesirable for data handling in digital photoelasticity. A preliminary study showed that the thickness of the slice has an influence on the appearance on the noise. In this paper, use of 10-step phase-shifting technique (PST) and refined three-fringe photoelasticity (RTFP) is explored to determine the isochromatic data as accurately as possible. A slice cut from a 3-D model of a spline shaft made of stereolithographic material is used for isochromatic determination. It is found that with suitable postprocessing, the quantitative results obtained from 10-step PST and RTFP are comparable. The relative merits of these two techniques for analysing stereolithographic models are brought out.

Evaluation of Hertzian contact parameters from whole field displacement data

Abstract: Evaluation of contact parameters in Hertzian contact from displacement data is studied. Based on complex potential approach, generic explicit equations for displacement field in the vicinity of the...

Adaptive Smoothing for Isoclinic Parameter Evaluation in Digital Photoelasticity

Abstract: In digital photoelasticity, one gets whole field information of isoclinic and isochromatic parameters based on intensity processing. Isoclinic values are undefined at isochromatic fringe contours and this appears as noise in the isoclinic phasemap which affects stress separation adversely. A new adaptive smoothing algorithm to remove the noise due to isochromatic-isoclinic interaction that automatically takes care of the isotropic points and π jumps present in the isoclinic phasemap is proposed. It is validated for the benchmark problem of a ring under diametral compression and verified for an angled bracket.

Contact Zone Evaluation of Dental Implants Using Digital Photoelasticity

Abstract: Use of dental implants in case of missing natural dentition is now common in clinical dentistry. The tilted implant configurations, which are inevitable in many clinical situations, are prone to higher stresses. The orientation of implants has a great influence on its structural integrity as high stresses around the implants adversely affect the osseointegration process and eventually fail due to the bone resorption. Hence, complete understanding of such complex systems demand better understanding of the bio-mechanics involved. Photoelasticity, a whole-field optical technique, is the right choice for analysing such implant configurations. Recent advancements in digital photoelasticity make it possible to evaluate isochromatics as well as isoclinic parameters over the entire model domain with considerable accuracy. However, these techniques have not been exploited in the field of implant dentistry and photoelasticity has been mostly used as a visualisation tool. This paper explores the use of modern photoelastic techniques for analysing the stress distribution due to an implant with an inclination of 15°. Further, this work also studies the high stress zones in the coronal region of this angled implant. The isochromatic data is post processed using least squares method for determining the contact parameters such as effective contact length and frictional coefficient.

Recent developments in brittle and quasi-brittle failure assessment of engineering materials by means of local approaches

Abstract: Brittle failure of components weakened by cracks or sharp and blunt V-notches is a topic of active and continuous research. It is attractive for all researchers who face the problem of fracture of materials under different loading conditions and deals with a large number of applications in different engineering fields, not only with the mechanical one. This topic is significant in all the cases where intrinsic defects of the material or geometrical discontinuities give rise to localized stress concentration which, in brittle materials, may generate a crack leading to catastrophic failure or to a shortening of the assessed structural life. Whereas cracks are viewed as unpleasant entities in most engineering materials, U- and V-notches of different acuities are sometimes deliberately introduced in design and manufacturing of structural components. Dealing with brittle failure of notched components and summarizing some recent experimental results reported in the literature, the main aim of the present contribution is to present a review of some local approaches applicable near stress raisers both sharp and blunt. The reviewed criteria allowed the present authors to develop a new approach based on the volume strain energy density (SED), which has been recently applied to assess the brittle failure of a large number of materials. The main features of the SED approach are outlined in the paper and its peculiarities and advantages accurately underlined. Some examples of applications are reported, as well. The present review is based on the authors’ experience over more than 15 years and the contents of their personal library. It is not a dispassionate literature survey.

Some Basic Problems Of The Mathematical Theory Of Elasticity

Abstract: Thank you for downloading some basic problems of the mathematical theory of elasticity. As you may know, people have search hundreds times for their favorite readings like this some basic problems of the mathematical theory of elasticity, but end up in infectious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they cope with some infectious bugs inside their computer.

Evidence for a protein transported through the secretory pathway en route to the higher plant chloroplast.

Abstract: In contrast to animal and fungal cells, green plant cells contain one or multiple chloroplasts, the organelle(s) in which photosynthetic reactions take place. Chloroplasts are believed to have originated from an endosymbiotic event and contain DNA that codes for some of their proteins. Most chloroplast proteins are encoded by the nuclear genome and imported with the help of sorting signals that are intrinsic parts of the polypeptides. Here, we show that a chloroplast-located protein in higher plants takes an alternative route through the secretory pathway, and becomes N-glycosylated before entering the chloroplast.

System for configuring a process control environment

Abstract: A control studio object system is disclosed which allows a process control environment to be easily and quickly configured or modified. The control studio object system includes a stencil portion having stencil items conforming to algorithms and a diagram portion to which the stencil items may be copied via a drag and drop operation. Because the stencil items are objects which contain all of the information required by a diagram portion to create an object that contains all of the information necessary to program the process control environment, the completed diagram portion reflects the actual configuration of the process control environment. Additionally, providing the stencil items as objects allows the diagrammed environment to be installed directly to nodes without requiring the diagram to be compiled or rewritten in a language conforming to the node.

Quality-guided phase unwrapping technique: comparison of quality maps and guiding strategies

Abstract: Quality-guided phase unwrapping is a widely used technique with different quality definitions and guiding strategies reported. It is thus necessary to do a detailed comparison of these approaches to choose the optimal quality map and guiding strategy. For quality maps, in the presence of noise, transform-based methods are found to be the best choice. However in the presence of discontinuities, phase unwrapping is itself unresolved and hence quality-guided phase unwrapping is not sufficient. For guiding strategies, classical, two-section, and stack-chain guiding strategies are chosen for comparison. If accuracy is the foremost criterion then the classical guiding strategy with a data structure of indexed interwoven linked list is best. If speed is of essence then the stack-chain guiding strategy is the one to use.