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Verification of Numerical Simulation Using a 3D Optical System for Measuring Deformations
Zakl, Alexandr ; Peterková, Eva (referee) ; Řiháček, Jan (advisor)
This master’s thesis discusses the current state of optical metrology and its place in manufacturing and optimization of parts made by deep-drawing technologies. First part is devoted to building a solid knowledge base in different fields that this thesis draws from. These fields are Optical Metrology, deep drawing of sheet metal and simulations using finite elements method. Subsequently, in the experimental part there are chapters dedicated to Measurement and creation of material models and measurement of grid markings on deep-drawn parts provided by ACO Industries, measured by photogrammetric system from German Company GOM metrology. Additionally, for reference to the measurement, FEM software called PAM-Stamp is used to simulate and predict the final state of the parts after manufacturing. Furthermore, optical metrology was used during creation of material models, data supplied by this analysis was used as an input for the simulations. The last chapter then deals with the evaluation and comparison of measured and simulated data and drawing conclusions about the reliability of optical systems and modern technologies in technical practice.
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Proposal of shaft alignment method for small rotors using digital image correlation
Hrůza, Vlastimil ; Pokorný, Jan (referee) ; Ščerba, Bořek (advisor)
The presented thesis deals with the design of a method for aligning small rotors, for which commonly available methods are not suitable. This is due to space restrictions around the coupling, which often do not allow installation of conventional alignment systems on the shafts. The proposed method therefore utilizes non-contact measurement of the surface of the shafts using digital image correlation (DIC). Calculation of misalignment and corrective moves is based on fitting the points measured on individual shafts with cylinders and evaluating the mutual position of their axes. To determine the area of applicability of the proposed method, sensitivity analysis was performed, which showed that the method gives good results for surface-accurate shafts with a uniformly applied speckle pattern for DIC measurement. Validation of the method was then carried out by measuring on a designed test rig using a commonly available laser alignment system. The validation measurement proved the functionality of the method and confirmed the conclusions of the sensitivity analysis.
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Automation of video extensometers using artificial intelligence
Leinweber, Vít ; Adamec, Tomáš (referee) ; Ščerba, Bořek (advisor)
This thesis deals with the automation of the use of video extensometers using artificial intelligence methods, specifically the implementation of a suitable algorithm for the recognition of the type of sample to be measured and the placement of a suitable software tool in the correct position on the sample in real-time. The theoretical part of the thesis describes digital image correlation, computer vision with a focus on object recognition, and machine learning with a focus on deep convolutional neural networks and their architectures for object detection. Based on the findings from the theoretical part of the work, the YOLOv8 algorithm is chosen as the most suitable algorithm for classifying the type of sample and determining its location in real-time. In the practical part of the thesis, a dataset containing three types of samples is created using the database of video extensometer manufacturer. The dataset is extended with images containing samples to be detected and augmented. The selected algorithm is trained, optimized, and tested using the created dataset. A genetic algorithm and a random search of the hyperparameter space are used in the optimization process. The best trained models of the YOLOv8 algorithm are compared with each other on two test sets and the best one is selected. Furthermore, the work with this algorithm as a detector integrated into the corresponding software for working with video extensometers is described. Finally, a method for correcting the effect of potential misalignment of samples in the images entering the detector is proposed.
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Application of the Digital Image Correlation Method for Asphalt Mixture Testing
Gavula, Dávid ; Dašek, Ondřej (referee) ; Šperka, Pavel (advisor)
Today's era offers more innovative methods for testing asphalt mixtures compared to conventional ones. The digital image correlation method is increasingly being used to supplement or even replace some asphalt mix testing procedures. The aim of this thesis is to verify the possible positive use of this method in further asphalt mix testing. In the theoretical part, the DIC method and the scientific papers in which the DIC method has been used in selected asphalt mixtures tests are presented. In the practical part, test bodies are first made from the asphalt mixture and then these bodies are subjected to a modified fatigue resistance test according to the norm ČSN EN 12697-24, whereby the use of the DIC method is investigated for the possible representation of crack initiation and actual crack development.
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Application of the digital image correlation in the measurement of residual stresses by the hole-drilling method
Plucnar, Tomáš ; Horák, Richard (referee) ; Halabuk, Dávid (advisor)
The thesis focuses on the measurement of residual stresses using digital image correlation (DIC). The work describes residual stresses and also derives an analytical description of the deformation around a drilled hole, which is essential for evaluating the experiment. The largest part of the thesis is dedicated to the measurement and evaluation of residual stresses. Within the framework of the thesis, measurements of residual stresses were conducted for samples with pre-drilled holes and also for solid samples into which holes were drilled. These measurements were then used to evaluate the effects of various DIC software settings on the assessed residual stress. Measurements on samples with pre-drilled holes were used to determine the impact of the random pattern density and the influence of the camera on the evaluated residual stress.
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Asphalt Layers using Fibreglass Composite Materials
Sadil, Dominik ; Hýzl, Petr (referee) ; Šperka, Pavel (advisor)
The diploma thesis deals with using of reinforcing composite materials in asphalt layers. These geosynthetic materials are in road construction used especially to reduce spreading cracks and extend the service life of the construction. As par of this work, test specimens of different types of asphalt layers were produced. These samples were subjected to laboratory testing, where the results of different reinforced asphalt slabs were compared. Within the diploma thesis primarily deals with the testing of the shear bond strength between asphalt layers in order to determine what are the other influencing factors of the test. Another part of the thesis is the 4-point bending test, during which a special technology in the form of a DIC camera was used to monitor the behavior of the asphalt layer over time.
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Use of the DIC method in solving basic problems of solid mechanics
Hrůza, Vlastimil ; Pokorný, Jan (referee) ; Ščerba, Bořek (advisor)
This bachelor’s theses deals with the solution of basic problems of solid mechanics using digital image correlation. The research part of the thesis presents some of the optical methods used for deformation measurement, digital image correlation in particular, whose history, principles, limitations and utilizations are described in detail. In the practical part of the theses, three experiments are carried out, which are then evaluated using digital image correlation and the results are compared with the created computational models. In the first experiment, strain on the tensile test specimens with notches is measured, the second experiment is focused on measuring strain when bending curved beams and in the final experiment, natural frequency of a fork produced by 3D printing is determined.
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Determination of Material Properties of Specimens Produced by Metallic 3D Printing
Zakl, Alexandr ; Peterková, Eva (referee) ; Řiháček, Jan (advisor)
This bachelor's thesis deals with mechanical properties and current status of 3D printing of metal parts, especially by DMLS/SLM method. Research part is dedicated to various technologies and suppliers in the field of 3D printing with emphasis on printing metal methods. Main purpose of this thesis is to connect the worlds of 3D printing and 3D optical measuring of deformation, so the part of research segment is dedicated to optical measuring and leading innovative company GOM. One of the leading product of this company is ARAMIS and in the context of this thesis it was present during the experiment as a instrument for measuring and inspecting material characteristics, and is present in research part where is mentioned a principle on which this device is working (digital image correlation) as is the device itsself. In the experimental part of this thesis, samples were printed on DMLS printer from company XactMetal, which were then submitted to a tensile test. Measurement was done using DIC based device ARAMIS and inspected for basic material properties in same named program.
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Comparison of strains determined by finite element method and by optical measurement system
Zajíček, Vít ; Hlavoň, Pavel (referee) ; Vlk, Miloš (advisor)
This thesis focuses on the comparison of numerical simulation and optical measurement of deformation of the turbinehousing made by Honeywell company. The numerical calculation performed by finite element method to simulate transient thermal load on the measured entity. Numerical result of the strain state of the body caused by temperature gradients. To verify the simulation is used an experimental digital correlation method VIC-3D. The thesis also mentioned the theoretical foundations of digital correlation methods and thermal analysis.
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