Wyniki wyszukiwania - BazTech

1

Finding a Crack and Determining Depth in a Material

Jesenik M., Trlep M.

Przegląd Elektrotechniczny

|

2013

|

R. 89, nr 2b

64--67

EN

The purpose of this paper is to find geometry of a crack (length and depth) in a conductive plate, on the basis of non-destructive testing with eddy currents. The position of a crack can be determined by taking into consideration the change in the magnetic density between the measured points. The depth is determined with the use of FEM model. The calculated test case points to an accurate determination.

PL

W artykule opisano metodę wyznaczania rozmiarów pęknięć w płytkach przewodzących, na podstawie testów z wykorzystaniem prądów wirowych, nieniszczących elementu. Metoda wykorzystuje wpływ pęknięć na zmianę gęstości pola w badanym rejonie. W analizie posłużono się metodą elementów skończonych. Otrzymane wyniki potwierdzają skuteczność działania.

2

Ultrasonic methods in diagnostics of glass-polyester composites

Wróbel G., Wierzbicki Ł.

Journal of Achievements in Materials and Manufacturing Engineering

|

2007

|

Vol. 20, nr 1-2

203-206

EN

Purpose: The aim of the work was to find relationship between the ultrasonic wave velocity and the strenght and Young's module in a glass-polyester composite. Design/methodology/approach: The experiments have been performed in three distinct phases. During the first phase, typical glass-polyester composite was ageing to get different mechanical properties. In the second phase, strength and ultrasonic properties of composite was testing. In the last of phases we compare changes of properties. Findings: The experimental results showed relationship between velocity of ultrasonic wave and strength and Young's module. Research limitations/implications: In those applications, in which polymer structural composites were subjected to a heat and mechanical load, it is essential to test the strength characteristics of the composites in the use of non-destructive methods. That enables contemporaneous status check of the structure and makes it possible to replace the bivalent evaluation scale (good - bad) with an incessantly gradable strength degradation scale for a material. Practical implications: The results of the investigation have shown possibility of using ultrasonic method to diagnosis of strength changes in composites. This method allowed to test working parts of machines or buildings, without destruction. Originality/value: The results of the investigations allow to confirm, that ultrasonics can be used to non-destructive testing of the strength and Young's modulus changes.

3

Fatigue and ultrasonic testing of epoxy-glass composites

Rojek M., Stabik J., Sokół S.

Journal of Achievements in Materials and Manufacturing Engineering

|

2007

|

Vol. 20, nr 1-2

183-186

EN

Purpose: The purpose of this paper was to find relationship between the degree of strength degradation caused by fatigue and the changes of ultrasonic wave characteristics such a wave velocity and damping coefficient. Design/methodology/approach: Epoxy-glass composites were subjected to oscillatory bending loadings with constant deflection. During fatigue procedure the force needed to achieve constant deflection was measured. During fatigue tests samples were subjected to ultrasonic tests. Additionally before fatigue test and after 300 000, 850 000 and 1 900 000 cycles parts of samples were subjected to destructive bending test. Findings: A good correlation between velocity of ultrasonic wave propagation and the degree of strength degradation of epoxy-glass composites caused by fatigue was found. Ultrasounds can be applied as effective tool to assessment of fatigue degradation of polymer composites. Research limitations/implications: Achieved results showed that research have to be continued. Fatigue with other loading conditions and for other composite materials is planned. Practical implications: The results of present research can be applied to elaboration of non-destructive method of measurement of the degree of fatigue degradation of polymer composites. Originality/value: Presented correlation between ultrasound wave characteristics and the degree of strength degradation caused by fatigue is original value of this paper.

4

Sensitivity analysis of electromagnetic quantities by means of FEM

Gawrylczyk K. M.

Journal of Technical Physics

|

2002

|

Vol. 43, no 3

323-334

EN

Sensitivity analysis determines the dependence of global or local electromagnetic quantities on geometrical or physical parameters expressed in the form of an objective function. The final aim of the field calculation methods is generally the design of an electromagnetic device. Solution of inverse problem on the basis of the finite elements method (FEM) makes the optimal shape design possible, as well as the identification of material cracks and flaws inside the conducting materials with the help of the eddy-current method. These tasks can be defined similarly for recognition of the spatial distribution of material parameters. The recognition takes place in iterative manner, basing on gradient information derived from the sensitivity analysis. The work deals with sensitivity evaluation in conjunction with finite element algorithms. It will be shown that the sensitivity analysis necessary to solve an inverse problem, requires only a low additional calculation cost.

5

Newly re-designed magnetic head for wire rope NDT

Miljavec D., Knez S.

Journal of Technical Physics

|

2002

|

Vol. 43, no 4

433-441

EN

The aim of the present paper is to analyse a newly re-designed magnetic head. Basic use of this head is in non-destructive testing (NDT) of wire ropes. The magnetic head system is composed of two main areas and three main parts. These areas are: magnetic flux leakage area in central region, and eddy current magnetic field area in outer side region of magnetic head. The analyses were carried out by analytic approach and by the finite element method. The value of induced voltage in flux leakage pick-up coils was calculated by axisymmetric 2D magnetostatic finite element analysis made by ferromagnetic rod to simulate the wire rope. Meanwhile, voltage induced by changes in eddy current magnetic field was calculated by a 2D transient linear motion finite element analysis. All numerically calculated results were compared with the measured ones on a geometrically similar ferromagnetic rod. Also, we have presented the measured results carried out by newly re-designed magnetic head on real steel wire rope with anomalies.