APPLICATION OF DIGITAL IMAGE CORRELATION FOR CURVED SURFACES TO DETERMINE DEFORMATION

Mechanical Engineering

Digital Image Correlation (DIC) is a powerful technique which is used to correlate two image segments to determine the similarity between them. A correlation image is formed which gives a peak known as correlation peak. If the two image segments are identical the peak is known as auto-correlation peak otherwise it is known as cross correlation peak. The location of the peak in a correlation image gives the relative displacement between the two image segments. Use of DIC for in-plane displacement and deformation measurements is well known. The basic principal of Digital Image Correlation (DIC) for measuring surface displacement considering curve surface such as cam is described in this paper. These components on the surface of an object are easily obtained using this method by recording images of surface before and after deformation. It is a non-contact optical measurement system, capable of high resolution surface deformation measurements derived from digital images captured of a surface undergoing a deformation or wear. The methodology presented in this paper uses a high speed camera to capture images of the curve surfaces and curved shape parts such as cam, from which surface deformation and/or wear measurements can be made. Wild use of this method in various fields is expected because the measurement can be performed easily and simply. In many cases residually stresses surface layers that are obtained by surface treatment or coating deposition contains significant stress gradients. These gradients affect the performance of component surfaces under the conditions of contact loading in service, such as impact, scratch and abrasion, wear, erosion, fretting fatigue, etc. The determination of residual stress in the close vicinity of sample surfaces, at the depths ranging from sub-micron to a few microns, is a challenging task that cannot be accomplished routinely using existing techniques, such tasks are easily completed using DIC. Cracks induced by external excitation on a material that has defects may generate the stress concentration phenomenon.

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