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Displacements measurements by Digital Image Correlation method with automatic Merging of data distributed in time

Marcin Malesa

Abstract

This dissertation presents a novel approach to displacements measurements with utilization of Digital Image Correlation (DIC) method. The developed enhancements of the standard method enabled long-term monitoring of object in hard environmental conditions in industries. DIC is a well-established technique for measurements of displacements, strains and shapes of different kind of objects. In the standard DIC, a measurement equipment has to be fixed in the same position next to the object during the measurements. If the equipment is moved, the traceability is lost and it is no longer possible to calculate displacements. This shortcoming of the standard method is especially important when long-term processes need to be investigated, which is usually the case in industries. The measurement equipment can not be left at the same position for whole time between consecutive measurements due to a risk of theft or damage. It creates a need to develop improvements of the standard DIC, which allow its application in the case, when the equipment is taken away and brought back to the object after a certain period of time. In the first part of the thesis a critical review of optical measurement methods is presented. The review shows advantages of DIC that makes this method well-suited for measurements in industries, but it also emphasizes that some problems connected with practical applications in industries need to be solved. Next, a series of measurements of objects in heat and power generating industries as well as in building engineering industries are presented in order response to the needs of these industries through introducing new applications and to investigate a feasibility of DIC in industries. Experience gained during the measurements helped to focus further works on development of the DIC method. Some minor improvements such as attuning a hardware configuration for in-situ measurements or developing more informative methods of visualization of the results are also part of this work. In order to overcome the biggest shortcoming of DIC method and enable long-term monitoring of objects, the concept of the automatic merging of DIC data distributed in time (and acquired from different views) is presented. In the thesis 2D DIC and 3D DIC versions of the merging method are described in details and the results of numerical simulations and real experiments are presented. In the two-dimensional version of the method the modified homography transform is utilized to bring the DIC data to the same coordinate system. The three-dimensional version of the method is based on geometrical operations carried out on point-clouds obtained from 3D DIC measurements. Images of the measured object that are the outputs from the automatic DIC data merging procedures can be consequently subjected to the standard DIC analysis. The developed enhancements of the standard DIC method enabled application of the method in monitoring of displacements of building struts. This practical application proves a potential of the novel method to become an important tool for building engineers. Potential applications in heat and power generating industries as well as in conservation of art are discussed in future works.
Record ID
WUTcd9bb2cc8c1f41beb8ed47e588467e72
Diploma type
Doctor of Philosophy
Author
Title in Polish
Pomiary przemieszczeń metoda Cyfrowej Korelacji Obrazu z procedurą automatycznego łączenia danych rozłożonych w czasie
Title in English
Displacements measurements by Digital Image Correlation method with automatic Merging of data distributed in time
Language
(en) English
Certifying Unit
Faculty of Mechatronics (FM)
Discipline
mechanical engineering / (technology domain) / (technological sciences)
Status
Finished
Start date
14-12-2011
Defense Date
19-03-2014
Title date
26-03-2014
Supervisor
Internal reviewers
External reviewers
Jerzy Kaleta, prof. Jerzy Kaleta, prof.,, External affiliation of publication: Wroclaw University of Science and Technology
Honored
yes
Pages
171
Keywords in English
novel approach to displacements measurements with utilization
Abstract in English
This dissertation presents a novel approach to displacements measurements with utilization of Digital Image Correlation (DIC) method. The developed enhancements of the standard method enabled long-term monitoring of object in hard environmental conditions in industries. DIC is a well-established technique for measurements of displacements, strains and shapes of different kind of objects. In the standard DIC, a measurement equipment has to be fixed in the same position next to the object during the measurements. If the equipment is moved, the traceability is lost and it is no longer possible to calculate displacements. This shortcoming of the standard method is especially important when long-term processes need to be investigated, which is usually the case in industries. The measurement equipment can not be left at the same position for whole time between consecutive measurements due to a risk of theft or damage. It creates a need to develop improvements of the standard DIC, which allow its application in the case, when the equipment is taken away and brought back to the object after a certain period of time. In the first part of the thesis a critical review of optical measurement methods is presented. The review shows advantages of DIC that makes this method well-suited for measurements in industries, but it also emphasizes that some problems connected with practical applications in industries need to be solved. Next, a series of measurements of objects in heat and power generating industries as well as in building engineering industries are presented in order response to the needs of these industries through introducing new applications and to investigate a feasibility of DIC in industries. Experience gained during the measurements helped to focus further works on development of the DIC method. Some minor improvements such as attuning a hardware configuration for in-situ measurements or developing more informative methods of visualization of the results are also part of this work. In order to overcome the biggest shortcoming of DIC method and enable long-term monitoring of objects, the concept of the automatic merging of DIC data distributed in time (and acquired from different views) is presented. In the thesis 2D DIC and 3D DIC versions of the merging method are described in details and the results of numerical simulations and real experiments are presented. In the two-dimensional version of the method the modified homography transform is utilized to bring the DIC data to the same coordinate system. The three-dimensional version of the method is based on geometrical operations carried out on point-clouds obtained from 3D DIC measurements. Images of the measured object that are the outputs from the automatic DIC data merging procedures can be consequently subjected to the standard DIC analysis. The developed enhancements of the standard DIC method enabled application of the method in monitoring of displacements of building struts. This practical application proves a potential of the novel method to become an important tool for building engineers. Potential applications in heat and power generating industries as well as in conservation of art are discussed in future works.
Thesis file
  • File: 1
    RozprawaMM.pdf
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Uniform Resource Identifier
https://repo.pw.edu.pl/info/phd/WUTcd9bb2cc8c1f41beb8ed47e588467e72/
URN
urn:pw-repo:WUTcd9bb2cc8c1f41beb8ed47e588467e72

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