Browsing by Subject "damage detection"

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Access status: Restricted ,
Badania łożysk ślizgowych z wykorzystaniem technik termowizyjnych
(Data obrony: 2016-01-26) Piasecki, Bartłomiej
Wydział Inżynierii Mechanicznej i Robotyki
Access status: Open Access ,
Computer-aided prototyping of interdigital transducers for the structural health monitoring of planar structures
(2013) Mańka, Michał; Ambroziński, Łukasz; Uhl, Tadeusz
In recent years an intensive research activity into the application of guided waves (GWs) for structural health monitoring (SHM) can be observed. For instance, Lamb waves (LWs) have shown a great potential in monitoring of thin, planar structures. However, due to the dispersive and multimodal nature of the LWs, their snapshots can consist of many pulses even for an intact structure, which makes damage detection very complex. Moreover, small PZT transducers, most commonly used in SHM systems, act normally as omni-directional wave sources, therefore, dense or sparse transducers networks are required for damage localization. Some of the above-mentioned drawbacks of single PZT emitters and sensors can be overcome using interdigital transducers (IDT) designed to excite and sense a single, selected mode. The mode-tuning is performed by changing the span of finger electrodes to match the wavelength of the excited mode for the selected frequency. An IDT is a directional source, therefore, it generates a wave steered to the direction perpendicular to the electrodes. The width of the excited main lobe can be determined by the length of the electrodes. Since many parameters of the IDTs infl uence the LWs propagation, techniques for the simulation of the wave excitation and propagation are needed. In the paper, numerical tools for the computer aided design and virtual prototyping of the IDTs are presented. The simulation technique is based on the frequency-dependent transfer function of the structure, and due to its computational efficiency it can be used for fast testing of IDTs’ performance and for preliminary transducer design for further finite element simulations, and prototyping.
Access status: Open Access ,
Damage localization and monitoring of load changes in truss structures
(2014) Mendrok, Krzysztof
In recent years one can observe an increasing interest of the researchers, both from academia and industry, in the development of systems for the monitoring of health structures. The main fields of application for these systems are rotating machinery, aircrafts and other means of group transport and civil engineering structures. Many of the latter, contain truss elements in its structure. That is why detection and possible localization of the fault in such a structures is crucial for the safety of its operation. In this paper the application of modal filtration to damage detection and localization in the truss structures is presented. The results of numerical simulation an laboratory experiment are shown.
Access status: Open Access ,
Low frequency identification of critical states of transmission tower structures
(2013) Szopa, Krystian; Iwaniec, Marek; Gołaś, Andrzej
Transmission towers are vital parts of the overhead power line infrastructures. Any damage to these supporting structures may result in decreased load-bearing capacity and, in consequence, their collapse. Failures of transmission towers are much more severe than power failures, as they not only cause interruption to the energy supply but can also result in considerable costs of infrastructure repairs and damage. Therefore, supporting structures of overhead power lines should be subjected to structural health monitoring. This paper presents a comprehensive database containing natural frequencies and strain energies of all elements for various (simulated) damage states. On the basis of structure modal parameters, by finding the correlation between natural frequencies of damaged structure stored in the created database and natural frequencies of the structure of interest, state of the test structure can be identified. In order to verify this method, a numerical experiment was carried out. Observing the strain energy variation as compared to the undamaged state makes it possible to localize the damage and assess its importance for the further structure exploitation.
Access status: Open Access ,
Programmable logic devices as a tool in structure’s damage detection applications
(2013) Maj, Wojciech; Mendrok, Krzysztof; Barszcz, Tomasz
Programmable logic devices is one of the most dynamically developing fields of technology today. It is widely used in many kinds of signal acquisition as well as data processing systems mainly because of it’s large flexibility and continuously growing abilities. It gives a designer a powerful tool, which allows for the creation of almost any kind of logic topology and any kind of data processing system, which additionally may be freely reprogrammable without any physical changes in the platform device. This paper briefly describes programmable devices technology contribution in the development of various SHM (System Health Monitoring) systems. The SHM systems mentioned in this paper have already been designed, built and successfully tested on real structures.
Access status: Restricted ,
Zastosowanie transformaty falkowej do wykrywania uszkodzeń w płytach
(Data obrony: 2014-02-06) Ciniewski, Maciej
Wydział Inżynierii Mechanicznej i Robotyki