Papers by Krzysztof Holak
Nondestructive Testing and Evaluation, 2016
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Bio-Algorithms and Med-Systems, 2016
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Journal of Vibroengineering, 2016
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Diagnostyka, 2011
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ABSTRACT
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Journal of Theoretical and Applied Mechanics
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Structural Control and Health Monitoring, 2015
ABSTRACT Deflection curve can be used to detect and localize damage in civil engineering structur... more ABSTRACT Deflection curve can be used to detect and localize damage in civil engineering structures. In this paper, a vision-based method applied for in-plane displacement field measurement of cantilever beams is presented. The deflection curve of the analyzed structure is computed by means of the digital image correlation. Damage is introduced into the structure. Resulting deflection curves are used as an input to the novel damage detection algorithms: line segments method and voting method. The algorithms are then compared with the second derivative method and assessed through the probability of detection procedure. Copyright © 2015 John Wiley & Sons, Ltd.
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tm - Technisches Messen, 2014
In this paper a vision-based method for measuring vertical deflection of large engineering struct... more In this paper a vision-based method for measuring vertical deflection of large engineering structures under load is presented in example of crane working arm deflection measurements. The deflection is computed by means of a digital image correlation technique embedded in the vision-based system. The results of measurements performed on the vision system were compared with data obtained using a Leica Laser Tracker system. The comparison revealed proper functioning of the developed vision system in industrial conditions.
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Key Engineering Materials, 2013
ABSTRACT In this paper, the developed vision system for in-plane measurement of a civil engineeri... more ABSTRACT In this paper, the developed vision system for in-plane measurement of a civil engineering structure's displacement fields is presented. The deflection curve is obtained as a result of analysis of two images of the construction: the reference one and the one acquired after application of the load. The principle of the method is calculation of the object’s point displacement by means of a normalized cross correlation coefficient. Perspective distortions of the construction’s image are removed by means of homography mapping, which allows two photographs of the object to be taken from two distinct points in space. There are discussed developed methodology, software tool and experimental results obtained from tests made on real civil engineering structure (girder) and compared with results received from measurement equipment integrated with girder. The system installed on the test stand and used for verification of optical methods consisted of a network of measurement nodes located in key points of the structure. Sensors measuring local deformations using strain gauges as well as the accelerometers measuring buckling of structure’s elements were placed in each node. Additionally a linear transducer for measurement of deformation of the lower beam of structure under investigation was used.
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ABSTRACT The paper presents an optical non-contact method of measuring the static deflection stru... more ABSTRACT The paper presents an optical non-contact method of measuring the static deflection structure in one plane. Displacements of measurement points of the structure under the load were computed by means of digital image correlation coefficient. The application of homography mapping enabled the deflection field to be computed from two images of the structure acquired from two distinct points in space. The model of the developed vision system were implemented and simulated in the MATLAB programming tool. The impact of the corner detector inaccuracy on the measurement results was investigated. The uncertainty propagation of the developed method was examined in a series of simulations. The distance of the camera and the focal length were investigated parameters of the system. In the paper, the variability of homography components as well as variability of displacements measured in each of the points of interest are presented
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Structural Health Monitoring, 2013
ABSTRACT Link to article: http://shm.sagepub.com/content/12/5-6/411.abstract In this article, the... more ABSTRACT Link to article: http://shm.sagepub.com/content/12/5-6/411.abstract In this article, the comparison of two noncontact measurement methods dedicated to civil engineering structures’ state examination is presented. The vision-based method computes the displacement field of the analyzed structure by means of the digital image correlation coefficient. The system consists of one or more high-resolution digital cameras mounted on a head or on portable tripods. The developed methodology and created software application embedded in an MS-Windows operating system are presented. The second system measures the deflection of the structures by means of a radar interferometer. In both cases, it is possible to measure many points on the structure simultaneously. This article presents a comparison of the displacement field measurement performed on a field setup, as well as the span of a steel bridge designed for tram traffic. Both systems are described, with special attention given to their application in measurements of civil engineering structures. This article demonstrates a preliminary test performed to verify both of the noncontact systems in relation to high-accuracy measurement devices, the precise surveying level, and the electronic dial indicator of displacement. The experiment was designed intentionally to simulate the geometric conditions of the real structure, but the displacement values were generated and controlled by the operator. As a key study, a steel viaduct subjected to an operational load was measured, as a type of structure for which the observation is required in terms of structural health monitoring. It was subjected to the operational load caused by tram traffic. Both examined systems were applied. The accuracy analysis of both systems was investigated, and the obtained results were discussed.
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Key Engineering Materials, 2012
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From Theory to Engineering Applications, 2013
ABSTRACT
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Measurement, 2013
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ABSTRACT Continuous exploitation of bridges causes their progressive consumption. Periodic observ... more ABSTRACT Continuous exploitation of bridges causes their progressive consumption. Periodic observations can help to control safety of such structures. Reliable description of behaviour of the bridge under load requires the use of method, which enables observation of many points simultaneously. The paper presents a comparison of deflection and vibration measurements performed on span of a steel bridge designed for tram traffic. Measurements were carried out during normal traffic. It was assumed to obtain the data necessary to determine the span deflection and vibration. Deflection measurements were carried out independently by two systems using different techniques: radar interferometry and digital image correlation. In both cases it is possible to measure many points on the structure simultaneously. Additionally, a set of accelerometers was installed on structure in order to measure vibrations. Vibrations were determined also by the ground-based interferometric radar. This novel measuring device operates on the basis of stepped-frequency continuous wave modulation and microwave interferometry technique. It allows to determine deformation and vibration frequency of the object through non-invasive observation of its behaviour at a frequency of up to 200 Hz. The authors present the comparison of test load results obtained by two systems and analysis of dynamics.
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Journal of Physics: …, Jan 1, 2011
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Papers by Krzysztof Holak