3D magnetovision scanner as a tool for investigation of magnetomechanical principles. J. Kaleta, D. Lewandowski, P. Wiewiórski - PDF

Solid State Phenomena Vol. 154 (2009) pp Online available since 2009/Apr/16 at (2009) Trans Tech Publications, Switzerland doi: /www.scientific.net/ssp D magnetovision

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Solid State Phenomena Vol. 154 (2009) pp Online available since 2009/Apr/16 at (2009) Trans Tech Publications, Switzerland doi: /www.scientific.net/ssp D magnetovision scanner as a tool for investigation of magnetomechanical principles J. Kaleta, D. Lewandowski, P. Wiewiórski Wroclaw University of Technology, Institute of Materials Science and Applied Mechanics, Smoluchowskiego 25, Wrocław , Poland Keywords: magnetomechanical effects, NDE, magnetovision, magnetovision camera Abstract. The study was aimed at designing a system for measuring the distribution of magnetic field around different magnetic objects including Smart Magnetic Materials. A new type of 3D camera for monitoring the magnetic field intensity was constructed. The measurement principle is based on internal magnetics properties of materials and the reverse magnetostriction effect (also called the Villari effect). No external magnetizing field is assumed; the entire magnetic effect is due to magnetomechanical principles. A new generation of Honeywell magnetosensors were applied to measure field intensity in 3D. Small size of measurement area (1.5 mm 3 ) allows quasi-local measurement of magnetic field. In the measurement head also Hall probes were alternately used. The aim of this stage of research was to construct the set for measurement of strength of a very weak magnetic field (10 A/m) around the magnetic objects. In scanner construction three axes for displacement in directions consistent with sensor axis were applied, which permits measuring magnetic field vector in geometrical coordination. Specialized software for data acquisition, processing and visualization of magnetic field vector has been written. In preliminary parts of the work magnetic scanner system allows determination of correspondence between mechanical and magnetic quantities. Main applications for this type of system are: reverse magnetostriction and magnetostriction in smart magnetic materials and composites, martensitic transformation induces plastic strain in shape memory alloys, NDT investigation, identification of local plastic deformation and texture of ferromagnetic materials, magnetic polygraphy and others. Measuring system may be used both as an entirely autonomous system as well as an integrated one, also through joint control with a typical mechanical testing systems for static and fatigue tests. Introduction Various devices for optical visualization are commonly used in techniques (optoelectronic cameras) and for thermal visualization (thermal infrared imagining cameras). In recent years there have been attempts at visualization of the magnetic field by means of the so-called scanners and magnetovision cameras. These devices make it possible to work out a new method from groups NDT and NDE called magnetovision, which has a number of very important applications in technology and medicine. All ferromagnetic materials can be an object of experiments. Most interesting area of applications of magnetovision is connected with making use of the inverted magnetostriction (also referred to as Villari effect and examining Smart magnetic materials [1,6]. The present scientific and engineering aim of such experiments is also identification of physical models of Villari effect, which would allow determining the deformation field on the basis of vector s components of the magnetic field intensity. The reasons presented above provided the present authors with motivation for creating the third generation scanner - magnetovision camera featuring the most up-to-date achievements in the whole range of sensors, software and mechanics. For over a decade in the team the present writers recruit from, a few generations of cameras and scanners have been developed, which ensure a magnetic image of materials exposed to various kinds of treatment, mechanic load specters and phase transformations. Earlier works present the basics of new diagnostic technique called magnetovision and point out the possibility of developing All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, (ID: , Pennsylvania State University, University Park, United States of America-04/06/14,22:47:56) 182 Smart Materials for Smart Devices and Structures measuring apparatus (magnetovision). The earlier works also present metrological properties of the effect [2,3,5,6], the possibility of application in fatigue process tests, in tests of breaking and texture and in athermal martensitic transformations. Not only can the system presented below be easily put to the uses described earlier, it has even a wider range of applications. The setup of the magnetic scanner The scheme of the system called Magscanner is presented in Figure 1, and Figure 2 presents its front view. The system consists of the following elements: mobile system of control and operation of the experiment consisting of the IBM computer T30 with a docking station, and service of full-size PCI cards, advanced control system ADDI-DATA APCI8001, mainly used in robotics scanner XYZ, advanced device adapted also for work with mechanical testing machines MTS. Guaranteed resolution of the measurement head scanning movement 2160 DPI. Working area of scanning: 410mm x 180mm x 200mmm, A) Magscaner/Maglab v X Megscaner 6DOF 3D manipulator Operator's control panel Acquisition system DT9804 Mobile Magscaner BT magnetics USB dockstation Contol unit sensor Bluetooth M CCD IBM 2631 PCI Multi-axis, 64 bit processor-controlled ADDI-DATA APCI8001 notebook IBM T30 P4-M 2,4GHz DB-50 Wireless USB WUSB of XYZ scanner XYZ scanner Z axis subsystem camera Z Y stepper driver Power supply system with additional ACU pack AVR controlled cycle loading analyzer, phase detector BT DGH ACQ DC motor Rotational axis subsystem HBM AE101 B) DB-50 to XYZ scanner Tensile testing subsystem Figure 1. Practical realization of the mobile magnetovision system adapted for complex tasks of determining of the magnetic field distribution in different applications A) applied measurement heads and their structure B). Solid State Phenomena Vol measurement head in the shape of triaxial measurement head based on Honeywell HMC105 magnetoresistors. These heads are easy to replace and measurements can also be made with Philips KMZ magnetoresistors as well as Hall elements made by Allegro Microsystems. A probe with sensors moves along the examined object at a constant distance (usually mm) from it, data acquisition system Data Translation (DT9804) with the so-called trigger for measurement and defining of the carriage positions, software dedicated to Magscanner/Maglab operating the whole of the system and ensuring results visualization. This package allows export of results to parameter systems CAD and visualization of the magnetic field vector 3D space, rotary axis designed for analysis of the magnetic field distribution around the axisymmetric elements cylinders and pipes. Main emphasis was laid on the possibility of quick tests done with a view to the scanner s use in industry, breaker a device enabling precise measurements of the magnetic field and mechanical values for materials in the shape of foil in tests of static breaking. Resolution of scanning movement of the beam equals 0.25 micrometers. Thanks to the use of the HBM AE101 class 0.1% amplifier it was possible to attain a large resolution of the force measurement in the range up to 500N. Measuring parameters of the scanner and measurement head Main parameters of the signal acquisition, their processing results visualization have been set out below: range of the magnetic field measurement - depending on head up to 100mT (hallotrons) scanning speed up to points /sec, scanning resolution max DPI (0.02mm) max. magnitude of XY map of magnetic field 20 million points (20000x1000), card sampling frequency DT khz, at 16-bit resolution. Fig. 1 presents the scheme of a measurement head with Hall elements. An integrated probe was made by sticking three measurement elements together (for Hx, Hy, Hz components respectively), each of which has its own independent conditioning system. Concentration on a small surface of a complete measurement setup of the magnetic field based on Hall effect allows quasi-point measurements, essential for the cylinder surface being analyzed. The measurement resolution attained equaled 100 T, in the linear range of the sensor 100mT. Figure 2. View of the Magscanner (ver. 2007) system, in which control-measurement part of the XY scanner (A), breaker (B), XY scanner (C) and mobile position of the magnetovision camera (D) 184 Smart Materials for Smart Devices and Structures Selected examples of the scanner s applications Examples of the scanner s applications and earlier versions of the magnetovision camera were presented in our earlier papers. Three cases have been chosen to illustrate its uses. In the first two magnetoresistors were used in order to perform measurements, and in the materials under examination occurred Hall effect. Magnetic field changes were very small of the order of earth background magnetic field. Figure 3 shows the results of the Villari effect measurement for Kirsh specimen exposed to cyclic load. A) B) C) Figure 3. Kirsch specimen and stress state (a model) A), the map of a deviator of stress state along load axis for Kirsch specimen (a model) B), The magnetovision image of the Kirsch specimen under load C) [2,4]. The second group of measurements was performed so as to check the usefulness of the magnetovision system for determining the magnetic field around objects submitted to technological procedures with a view to checking their correctness ( e.g. cutting, laser ablation, electro-discharge drilling, micro-layer plotting, quality of magnetic printing, etc.) Figure 4 contains selected examples. A) B) C) Figure 4. Examples of the use of the magnetic field stream disturbance for detection of changes on the ferromagnetic s surface A) - metal plate with drilled hole, B) - steel strip horizontally (changes of magentic field shows deformation and cutting edges), C) - vector field observed over thin cupper wire (current flow through it). In the third successive case (Fig. 5 and Fig. 6) composite magnetic rods made of strontium ferrite were the object of our experiments. The cylinder s diameter equaled 9.60 mm and its working length 220 mm. In order to verify the experimental method we used cylinders locally demagnetized but without mechanical defects and cylinders with introduced programmed mechanical defects in form of drilled holes, defects and an induced crack. Reference cylinders had neither mechanical defects nor demagnetized areas. To perform the measurement effectively we d=30,16 mm Solid State Phenomena Vol had to rearm the measurement head by having a three-axis Hall probe mounted on it. The probe moved at a constant distance (0.5 mm) from the cylinder. a) b) H unmagnetized zone A B C D 1 2 a) b) H cuting area holes d= 1[mm] [mm] Hx M H crack line 5mm 3 c) 4 M c) H A-D H A-D 40mT Z d) H A -C A -D H [ o] D Figure. 5 Results of tests for a cylinder subjected to a local influence of external magnetic field. a) magnetic field map b) distributions of magnetic field [H] for successive longitudinal cuts c) d) distributions of changes [H](l (mm), (angle)) for marked transverse cross sections and (on the right side) their image in polar coordinates. Figure 6. Results of tests for a cylinder subjected to local mechanical defects. a) The manner and place of applying mechanical defects, and magnetic field map [H] with marked crack place and its enlargement [next to] distributions of changes [H](l (mm), (angle)) for transverse cuts lying in the area of the opening 5mm and a detected crack. Conclusions 1. A new generation scanner (magnetovision camera) with the replaceable head containing magnetoresistors and Hall probes has been developed. 2. The scanner can find application as one of the NDE methods for testing the quality of diverse technological processes and for identification of cross models of magnetomechanical field. 3. The scanner system can be used as an entirely autonomic one and as commonly controlled together with a typical material testing systems for static and fatigue experiments Acknowledgment This research was carried out partially as part of Commissioned Project PBZ-KBN- 115/T08/2004 financed by the Ministry of Education and Science, the State Committee for Scientific Research. 186 Smart Materials for Smart Devices and Structures References [1] J. Kaleta, Magnetomechanical Effect in Fatigue Investigations of Ferromagnetics; Proc. of EUROMAT-2000, Tours, 7-9 November 2000, France, Vol.2, s ; 2000; Tours. [2] J. Kaleta, P. Wiewiórski, Magnetovision as a Tool for Investigation of Fatigue Process of Ferromagnetics; Proc. of Fatigue 2001, Sao-Paulo December; 7; 2001; Sao Paulo. [3] J. Kaleta, P. Wiewiórski, W. Wiśniewski, Badanie tekstury blach ferromagnetycznych z wykorzystaniem efektu Villariego, Sympozjum Mechaniki Zniszczenia Materiałów i Konstrukcji, 2003, Augustów. [4] J. Kaleta, R. Górecki, Metoda wizualizacji pól krzyżowych w tarczach obciążonych cyklicznie. Zmęczenie i mechanika pękania; Materiały XIX Sympozjum Zmęczenia i Mechanika Pękania; 2002; Bydgoszcz. [5] J. Kaleta, P. Wiewiórski, W. Wiśniewski, Magnetyczna pamięć historii odkształcania materiału ferromagnetycznego; IX Krajowa Konferencja Mechaniki Pękania. Kielce-Cedzyna, września Kielce: Wydaw. PŚwiętokrz s [6] J. Kaleta, P. Wiewiórski: Detekcja defektów w magnetycznych prętach kompozytowych z użyciem skanera o dużej rozdzielczości. Acta Mechanica et Automatica vol. 1, nr 1, s Smart Materials for Smart Devices and Structures /www.scientific.net/SSP.154 3D Magnetovision Scanner as a Tool for Investigation of Magnetomechanical Principles /www.scientific.net/SSP
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