The paper presents the measurement process and test results for six thin-walled plates with different dynamic characteristics caused by different defects of welded joints. The tests were carried out using non-destructive testing (NDT). The authors made an attempt to determine the validity of the use and degree of effectiveness of the tests based on laser vibrometry in detecting defects in welded joints. The tests of welded plates were carried out using displacement laser sensors and piezoelectric accelerometers, while the source of vibration extortion was a modal hammer. In the adopted measurement methodology, the application of accelerometers was to obtain the reference data, which allowed for comparison with the measurement data obtained from the laser vibrometer. The analysis of the obtained measurement data, in the fields of time and frequency, made it possible to verify the correctness of the data obtained by means of laser vibrometry and to determine the requirements which are necessary for the correct performance of NDT tests and in the future structural health monitoring (SHM) system of welded joints with the use of a laser vibrometer. The mathematical model developed in the MSC software Pastran-Nastran was also used in the work. The model was developed for the purpose of mutual verification of the measurement and calculation tests. At the present stage of work, it can be stated that the results obtained by laser vibrometry methods should be treated as a supplement to the research conducted with traditional piezoelectric accelerometers. In certain situations, they can be used as an alternative to accelerometers, due to the fact that laser sensors do not require direct contact with the examined object. Where the object under test may be in a strong electromagnetic field, optical sensors are better suited than contact sensors.
Increasingly popular remote work requires the use of modern network technologies to provide employees in a remote location with access to the company’s IT resources. The answer to the needs of remote access to files and server services can be the use of clouds and VPS. However, this involves high costs and requires entrusting the enterprise’s data to the providers of these services. Both for reasons of data security and too high costs, enterprises sometimes cannot use these technologies. The solution to the problem may be the use of encrypted VPN tunneling, which allows the device to be connected at a remote location to the company’s local network and use its resources as if it was connected to the local network with physical transmission medium.
The paper presents a synthetic characterization of modern methods of manufacturing or regenerating machine elements. Considered methods are machining and additive methods, in particular 3D printing in the FDM/FFF technique. For the study, the authors made samples of the holder bracket using selected methods. Samples made by machining operations, 3D printing with various filling were tested. The paper contains a technical and economic analysis of the production of a holder bracket using the discussed methods. The dynamics of steel and FDM/FFF printed samples were also assessed by determining their resonance curves. The vibration magnification fac-tors were analyzed -the quotient of the vibration amplitudes in the resonance to the static deformations that occurred under the influence of the constant force and the location of the vibration resonances -the natural frequencies for individual vibration modes. The study's main objective is to assess the possibility of emergency changing the manufacturing technology of selected machine components. The authors were interested in partially replacing costly and not environmentally friendly milling with 3D printing. Machine elements can be manufactured by printing in classical machine building and emergency conditions to replace a damaged component temporarily (e.g., on a ship, for the time of arrival at a port or shipyard). The main assumption guiding the authors during the preparation of this publication was the analysis of the possibility of using the production of "ad hoc" prepared spare parts and their use in the event of a lack of access to parts made of the intended materials.
The article shows the results of the preparatory steps taken to create the artificial intelligence used in the automatic recognition of defects in ship thin-walled structures. The above steps are used to create a university private cloud and a computer system maintaining a dataset of vibration signal samples. In the article, a prototype of the private cloud was designed and developed, a model of the vibration sample was prepared, and a microservice was designed aimed at sharing the obtained data. The article demonstrates the results of the completed development.
Creating the required IT infrastructure to enable the ability for comfortable remote working is not an easy task. Improper configuration can create the possibility of taking over the whole bandwidth of the link by one device. Increasing bandwidth introduces extra costs and does not completely eliminate the problem – it will be more difficult to take over the whole bandwidth, but it is still possible. The solution to the problem may be the use of clouds and VPS, but it is associated with high costs and the need to entrust company data to providers of these services. Due to security and too high costs, this may not be an optimal solution. An alternative solution may be to use QoS along with PCQ. This mechanism allows to ensure equal division of the bandwidth between the devices under its control. With an appropriate configuration, QoS can eliminate the problem of taking over the whole bandwidth and ensure equal access to resources.
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