Engineering Applications of Residual Stress, Volume 8 Proceedings of

Engineering Applications of Residual Stress represents one of eight volumes of technical papers presented at the Society for Experimental Mechanics Annual Conference & Exposition on Experimental and Applied Mechanics, held at Uncasville, Connecticut,

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Armando Albertazzi Jr*, Matias R. Viotti, Pedro Buschinelli, Allan Hoffmann, Walter Kapp Universidade Federal de Santa Catarina, Mechanical Eng. Department, Florianopolis, SC, CEP 88.040-970, Brazil, *e-mail: [email protected]

ABSTRACT This paper describes three different optical systems designed to be used outside the lab for pipeline inspections. The first one is a robust and portable ESPI based hole-drilling unit with radial sensitivity used for residual stresses measurement. The device has a special diffractive optical element that produces an achromatic interferometer. The displacement component around the hole drilled is measured by ESPI with radial in-plane sensitivity and is fitted by least square methods to evaluate residual stresses. An infield application for analyzing the integrity of a gas pipeline is presented as an application example. The second system is a conical laser triangulation device to measure the geometry of the inner surface of pipes. A laser beam is deflected by the tip of a 45° conical mirror and produces a radial light plane that intercepts the inner surface of the pipe producing a bright ring all way around 360°. The image of the light ring is used to compute the radius of about 1400 points in each section while the device is moved along the pipe axis. Finally, the third system uses active photogrammetry to measure in cylindrical coordinates the details of the inner geometry of pipe junctions and welding seams. It was designed to inspect welded joints, to check weld seam quality as well as to identify transverse and angular misalignment between adjacent sections.

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Introduction

Light is a very rich and powerful information carrier. Intensity, trajectory, wavelength/color, polarization state, speed and coherence state are light properties that can carry information. The ability to manipulate light to change one or more property as a function of a quantity of interest is the basic principle behind any optical measurement principle. Mechanical, chemical, electrical, thermal, temporal quantities can be measured by optical methods. It is possible to measure quantities in the nanoworld as well to measure distances of remote galaxies over 10 25 m far away from earth. From the engineering point of view, optical measurement methods are very attractive for two main reasons: high speed and non-invasiveness. The ability to measure at the light speed makes it possible to handle highly dynamic events and to acquire a large amount of data in a very short time. Light usually does not scratch, deform, wear or damage most engineering surfaces

T. Proulx (ed.), Engineering Applications of Residual Stress, Volume 8, Conference Proceedings of the Society for Experimental Mechanics Series 999, DOI 10.1007/978-1-4614-0225-1_1, © The Society for Experimental Mechanics, Inc. 2011

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2 or materials. However, light behavior can be influenced by environmental disturbances like temperature, moisture, vibration, dust or pressure, what make the design of an optical measurement system a careful task