scholarly journals Application of Laser Vibrometry to Assess Defects in Ship Hull’s Welded Joints’ Technical Condition

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 895
Author(s):  
Adam Szeleziński ◽  
Adam Muc ◽  
Lech Murawski ◽  
Marcin Kluczyk ◽  
Tomasz Muchowski
Keyword(s):  
Optical Sensors ◽  
Welded Joints ◽  
Measurement Data ◽  
Technical Condition ◽  
Laser Vibrometer ◽  
Laser Vibrometry ◽  
Destructive Testing ◽  
Laser Sensors ◽  
Measurement Methodology ◽  
The Mathematical Model

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.

A novel geometry error measurement methodology for coaxiality evaluation

2020 ◽  
pp. 095440542096817
Author(s):  
Zhang Yingjie ◽  
Ge Liling
Keyword(s):  
Weighted Least Squares ◽  
Measurement Data ◽  
Coordinate Frame ◽  
Laser Sensor ◽  
New Device ◽  
System A ◽  
Measurement Methodology ◽  
Measurement Principle ◽  
3D Profile ◽  
Geometry Error

In this paper, we proposed a new device for geometry errors measurement and coaxiality evaluation, and the corresponding methodology for coaxiality evaluation from measurement data is presented, which allows to characterize multiple holes at a time. Unlike traditional measurement system a laser sensor is mounted onto out of the holes so that multi-hole surfaces can be “seen” by the senor when it rotates around a fixed axis. First the intersections (or ellipse profiles) of the sensor’s scanning plane and holes, are computed by fitting. Then, the center coordinates and profile points of the ellipse are computed and transformed to the 3D global coordinate frame. Finally the centerline of the hole is determined from the 3D profile points by using a weighted least-squares fitting algorithm. In addition, to reduce the effect of noises on the measurement result, error analysis and compensation techniques are studied to improve the measurement accuracy. A case study is presented to validate the measurement principle and data processing approach.

INVESTIGATION OF TRANSVERSE CRACKS IN ANNULAR WELDED JOINTS OF MAIN GAS PIPELINES LINEAR PART

2021 ◽  
pp. 34-41
Author(s):  
V. A. Zaznobin ◽  
A. V. Nekrasov ◽  
A. V. Pankratov
Keyword(s):  
Welded Joints ◽  
Linear Part ◽  
Correct Identification ◽  
Gas Pipelines ◽  
Destructive Testing ◽  
Transverse Cracks ◽  
Additional Control ◽  
Non Destructive

Statistics of accidents and incidents on main gas pipelines in recent years indicate that almost half of the technogenic events occur due to depressurization in the area of annular welded joints, mainly joints containing defects made during construction and installation work during the construction of gas pipelines. The assessment of the degree of danger and the timing of external inspection and repair or replacement of defective annular welded joints largely depends on the quality of non-destructive testing, the correct identification of the types of defects and the objective determination of their geometric dimensions. To increase the reliability of the assessment of the degree of danger of the detected defects, it is necessary to use additional control methods, in particular, destructive ones. The paper presents the results of surveys and tests of metal fragments of annular welded joints of main gas pipelines containing transverse cracks of annular welded joints in order to determine the causes of the formation of these defects and to assess the degree of danger of the detected transverse cracks of the installation welds of main gas pipelines.

scholarly journals Step-by-step control of target efficiency indices of the control and measuring equipment stock applied in construction and housing and communal services

2018 ◽  
Vol 170 ◽  
pp. 01010 ◽  
Author(s):  
Rustam Khayrullin ◽  
Pavel Ivanov
Keyword(s):  
Mathematical Model ◽  
Finite Difference ◽  
Measuring Equipment ◽  
Technical Condition ◽  
Measuring Instruments ◽  
Finite Difference Equations ◽  
Target Values ◽  
The Mathematical Model ◽  
Step Control ◽  
Different Levels

The mathematical model is considered for the formation and implementation of development strategies of the stock of control and measuring instruments (CMI) applied in construction and housing and communal services(HCS), and step-by-step control of efficiency target values of the stock. The model is based on a system of finite - difference equations describing the change of number of the CMI samples with different levels of technical perfection and technical condition at each planning interval. The model allows calculating the required number of CMI for procurement and repairs in the various groups for provide target values of efficiency indices at each planning interval. Controller is number of modern CMI samples for procurement and number of modern and obsolete faulty CMI samples for the repairs. The results of calculations are presented.

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