Application of holographic interferometry in the analysis of stress states in a crack root area

Abstract

This paper deals with the visualization and analysis of interaction of a cutting wedge disintegrator with plastic at low loads. For exploratory research, a contactless optical holographic interferometry method was used, allowing a comprehensive picture of the stress state when opening microcracks. An experimental model was set up for the purposes of the research. The structure of the model as well as its geometric parameters had to comply with the applied optical method. The method of holographic interferometry enabled us to record even the initial stages of the crack. Pictures of holographic interferograms allowed us to observe stress fields on the cutting wedge as well as on the loaded body in the form of interference fringes. In order to record the interferograms, we used the method of two exposures so that we gained double-exposure interferograms, which represent the state of the object during the second exposure. The first exposure was caused by superposition of object-related and reference wave after the object was subjected to a load; the second exposure occurred after the load was removed. We used quantitative analysis to determine stress intensity coefficients from holographic interferograms as followed by the calculation of stresses with respect to axes x and y . The analysis was done for loading forces 1.57 N and 3.14 N. As the load applied to the cutting material was increasing, the density of interference fringes was increasing, too.

Applied Research of Applicability of High-Strength Steel for a Track of a Demining Machine in Term of Its Tribological Properties

“…The application research can be developed only if the basic research has a sufficient progress. There was a problem: the area of the high-strength steels is generally worked out well, however, there is a gap for optimizing the lifespan of the welded high-strength structures [25][26][27][28][29]. Safety is the primary condition for every structure.…”

A mathematical Theory of Elasticity for Photoelastic Experimental Hybrid Method

“…However, this method provides only point-to-point information and their use can be arduous if the number of gage locations becomes large [5]. Other methods such as holography and speckle method have also been used but require sophisticated optics [6]. Moiré technique, on the other hand, requires some pattern to be inscribed onto the surface to be analyzed [7].…”

A New Pattern Quality Assessment Criterion and Defocusing Degree Determination of Laser Speckle Correlation Method

“…The common methods are divided into interferometric and imaging-based methods. Interferometric methods include electric speckle pattern interferometry (ESPI) [ 1 , 2 , 3 , 4 ], shear interferometry [ 5 , 6 ], and holographic interferometry [ 7 , 8 , 9 ], and these methods generally produce subwavelength accuracy. Adopting high-efficiency phase extraction methods, such as the temporal phase-shifting method [ 10 , 11 ], spatial carrier phase-shifting method [ 12 , 13 ], and Fourier transform method [ 14 , 15 ], nanometer accuracy can be achieved under laboratory conditions.…”