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Introduction to the examination of thin-walled structures using the vibrodiagnostic method

Szeleziński Adam, Muc Adam, Murawski Lech, Doan Do Van

Journal of KONES

2019

Vol. 26, No. 4

241--248

The article presents a methodology of non-destructive diagnostic vibratory tests of welded plates with geometrical parameters that classify them into a group of thin-walled panels. On the basis of such plates, most ship constructions are created. In previous works, the authors dealt with the study of welded joints in plates with significant thicknesses and developed for them a number of methods for assessing the quality of welded joints. Vibrodiagnostics is a NDT method that allows the use of a variety of techniques and tools. It enables measurements to be made in both a contact and non-contact way depending on the requirements of the structure and the environment. Vibrodiagnostic method is one of the most modern NDT methods, which uses modern measurement tools and computer analysis of data. On the basis of the developed methods, the authors intend to verify their application to plates from real welded constructions, which will be performed in typical shipyard conditions by welders. Such tests are important due to their use for the construction of a real SHM ship construction monitoring system. These methods allow for the examination of the condition of ships’ structural plates and can detect defects in welded joints that prevent ships from operating under severe sea conditions. The article presents the laboratory stand, the sensor layout, results, and their initial analysis.

Time – frequency dynamic characteristics 2D in the quality assessment of welded joints

Szeleziński A., Muc A., Murawski L.

Journal of KONES

2018

Vol. 25, No. 2

357--361

The authors of the article have been looking for a new parameters and dynamic characteristics, which can be applied to non-destructive testing of welded joints. All characteristics have been based on recorded data generated during the vibration tests of welded joints with and without failures. The article deals with the methods of assessing welding joints using 2D: time – frequency dynamic characteristics. A calculation procedure used for analysing simultaneous changes of the response modules, registered by acceleration sensors was presented. Vibrations amplitudes were transformed to a function of time and frequency (simultaneously) and presented over 2D time – frequency characteristics. The analyses of the characteristics were performed for a plate without any welded joint, for a plate with non-defected welded joint and for a plate with a welded joint defected by an edge bonding. Having analysed registered 2D time – frequency dynamic characteristics it can be noticed that presenting the responses analysed simultaneously over the time and frequency allows evaluating if examined system maintains non-linearity and, at the same time, it allows to indirectly assess the quality of the welded joint. The proposed measure parameters of the quality of a welded joint can be defined as a dispersion of colours on the obtained characteristics. The faults (and the vibration nonlinearity) of the welded joints is bigger if the dispersion is greater.