CZ25629U1 - System of instrumented measuring of indenter indentation parameters - Google Patents

Description

Technical field

The technical solution relates to a system of instrumented measurement of indentor indentation parameters comprising a test specimen loading mechanism and a measuring device provided with a displacement sensor and a load sensor.

Background Art

The classical methods of measuring the mechanical properties of materials are time consuming and expensive, requiring the production of special test samples. The most widespread mechanical tests are the tensile test, the bend test and the hardness test. The usual output of these tests are the graphical dependencies between the stress and strain of the test material. There are non-destructive methods and devices to perform a rapid assessment of material properties with sufficient accuracy, including methods of automated indent indentation. These methods are used in the development of new materials and equipment, the assessment and timely estimation of possible deviations in their performance during operation. The basic properties that are found are hardness, modulus of elasticity, yield strength, breaking strength, as well as elastic and plastic deformation energy, hardening exponent and grain size.

The hardness measurement is based on the indentation process where the indentor penetrates the surface of the sample to be examined and the hardness number is then determined by the geometric indentation parameters, depending on the applied load. The basic geometrical parameters are the Brinell imprint diameter, the Vickers diagonal, or the Rockwell indentation depth. Techniques that determine correlation between hardness number and basic mechanical properties are well known in engineering practice and have been standardized, eg, GOST 18835-73, GOST 22762-77. Theoretical and experimental studies show that the indentation test gives the most objective results of the determined mechanical properties of materials and coatings, using not only one hardness value at a given load, but continuous recording of the load and unloading process parameters, the so-called load-depth curve [Anisimov Evgeniy, Puchnin Maxim : Reduction of Elastic Module of Titanium Alloy Ti-6A1-4V by Quenching, in Book of Abstracts, Local Mechanical Properties, 2012, Slovak Republic, ISBN 978-80-553-1163-0, Puchnin Maxim, Anisimov Evgeniy: The Method of Accounting of Elastic Deformation Occur During the Automated Packing Test, in Conferences Proceedings, COMAT, 2012, Czech Republic, ISBN 978-80-87294-34-5]. This method is called instrumented material testing by indentor injection. The load-depth curve then describes the characteristic behavior of the material under the influence of elastic, elastic-plastic and plastic deformation [ASTM WK381, US 6 718 820 (Kwon) 13.04.2004],

The measuring device used for indentor pressing testing includes a load sensor, a displacement sensor [PCT / KR02 / 01351 (Lee) 18.07.2002, PCT / IB2005 / 002275 (Beghini) 01.08.2005, US 2009/0107221 Al (Ernst) 30.04. 2009]. There are various methods of indentor loading, such as hydraulic [US 4 059 990 (Glover) 29.11.1977], pneumatic [US 4,182,164 (Fohey) January 8, 1980, US 2,839,917 (Webster) June 24, 1958, US 4,534,212 (Targosz) 13.08. 1985], electromechanical [US 4 611 487 (Krenn) 16.09.1986, US 6 718 820 (Kwon) 13.04.2004, PCT / IB2005 / 002275 (Beghini) 01/08/2005, US 7,066,013 B2 (Wu) US 2011/0132078 Al (Wu) June 9, 2011] using electric motors with gear gear [US 4,635,471 (Rogers) January 13, 1987] or with belt drive [US 5,616,857 (Merck) April 1, 1997], electromagnetically or piezoelectric elements [US 4,304,123 (Ashinger) December 8, 1981, US 6,026,677 (Bonin) February 22, 2000], mechanical using weights [U.S. Pat. No. 3,367,174 (Affri) February 6, 1968, U.S. Pat. 1978], crank and lever mechanisms [US 4 435 976 (Edward) 13.03.1984, US 4,535,623 (Gilberto) 20.08.1985, US 4,182,164 (Fohey) 08/01/1980, US 2009/0107221 Al (Ernst) 30/04/2009, EP 2 345 884 A2 (Sawa) January 6, 2011], Hydraulic [US 4 059 990 (Glover) November 29, 1977] and spring-loaded [US 4 312 220 (Borgersen) January 26, 1982] load meters, piezoelectric elements [US 6,026,677 (Bonin) 22.02.2000], capacitive [US 7 066 013 B2 (Wu) 27.06.2006, US 2011/0132078 Al (Wu) June 9, 2011] and strain gauge sensors [US

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US 9 304 463 (Vandeijagt) 27.01.1976, US 4 304 123 (Ashinger) 08.12.1981, US 4 611 487 (Krenn) 16.09.1986, US 6 718 820 (Kwon) 13.04.2004, US 2011/0132078 Al (Wu) June 9, 2011] are used to measure load values. Methods based on laser optics [US 5,616,857 (Merck) April 1, 1997, US 6,026,677 (Bonin) 22.02.2000, PCT / KR02 / 01351 (Lee) July 18, 2002, PCT / IB2005 / 002275 (Beghini) 01.08. 2005, US 6,755,075 B2 (Nagashima) January 29, 2004] and electro-optical drives [US 4 312 220 (Borgersen) January 26, 1982], capacitive [US 7,066,013 B2 (Wu) 27/06/2006, US 2011/0132078 Al (Wu) June 9, 2011], potentiometric [EP 2 390 649 Al (Sakuma) January 18, 2010] Electromagnetic [US 4 159 640 (Lévéque) July 3, 1979, US 4 182 164 (Fohey) January 8, 1980, US 4,435 976 (Edward) March 13, 1984, US 4,534,212 (Targosz) August 13, 1985, US 6,718,820 (Kwon) April 13, 2004, US 4,034,603 (Leeb) July 12, 1977], piezoelectric [US 6,026,677 (Bonin) 22.02.2000] and strain gauge sensors [Degtyarev VI, Lagveshkin V.Ya. Are often used to record the penetration depth, or current linear displacement, of the indent during the indentation test, or the current linear displacement of the indent during the indentation test, is often used to record the penetration depth or the current linear displacement of the indentation test. .

The accuracy of measuring the total linear displacement of the indentor depends on the sensitivity of the indentation depth sensor, which has its resolution and allows the recording of a definite number of values at a given displacement. Problems of accuracy of recording of small indentor shifts are usually solved by means of laser optics or electromagnetic systems. The accuracy of the measurement depends not only on the discretion of the recorded value, but also on the distance of the sensor from the indentor. The larger number of elements between the sensor and the indentor increases the measurement error because the measurement itself is then influenced by the stress-strain states of these elements depending on the load conditions, the number of cycles and the atmospheric parameters, in particular pressure and temperature. The displacement sensor is often part of the load mechanism and the process of correct interpretation of results is complicated during the indentation [US 2 839 917 (Webster) 24.06.1958, US 4,159,640 (Levéque) 3.07.1979, US 4 435 976 (Edward) 13.03.1984 U.S. Pat. No. 3,367,174 (Affri) June 6, 1968, U.S. Pat. No. 4,245,496 (January 20, 1981, U.S. Pat. No. 4,312,220) January 26, 1982, U.S. Pat. No. 4,534,212 (Targosz) August 13, 1985, U.S. Pat. No. 075 B2 (Nagashima) 29.01.2004, US 7 066 013 B2 (Wu) June 27, 2006], Existing devices that implement an instrumented indentation method with high accuracy and repeatability of the measurement process have larger dimensions [US 5,616,857 (Merck) 01.04 .1997, US 2011/0132078 Al (Wu) June 9, 2011], are often limited by the range of load used [US 4,159,640 (Levéque) July 3, 1979, US 4,304,123 (Ashinger) December 8, 1981, US 4,611,487 ( September 16, 1986, US 6,026,677 (Bonin) February 22, 2000, PCT / KR02 / 01351 (Lee) July 18, 2002, US 6,718,820 (Kwon) April 13, 2004, US 2009/0107221 Al (Ernst) 30.04 [US 4 534 212 (Targosz) 13.08.1985, US 4,535,623 (Gilberto) August 20, 1985, PCT / KR02 / 01351 (Lee) July 18, 2002, US 6,755,075 B2 (Nagashima) 29.01 .2004], measures total linear indent feed. There are also known difficulties in identifying failure initiation parameters from load-depth and stress dependencies in the measurement of coating properties [PCT / US00 / 09940 (White) April 13, 1999, N.H. Faisal, J.A. Steel The Use of Acoustic Emission to Characterize Fracture Behavior During Vickers Indentation of HVOF Thermally Sprayed WC-Co Coatings, Journal of Thermal Spray Technology, Vol. 18 (4), p.525-535, (2009), Markus G.R. Sause, Daniel SchultheiB. Acoustic emission investigation of coating fracture and delamination in hybrid carbon fiber reinforced plastic structures, Journal of Acoustic Emission, 26, p. .1989].

Ashinger [US 4,304,123 (Ashinger), Dec. 8, 1981] describes the possibility of using strain gauge sensors that are attached to a flexible arm to register low load and displacement values of the indent. The measurement of higher indentation parameter values is described by [Degtyarev V.I., Lagveshkin V.Ya. Perenosnaya tenzometricheskaya golovka dlya opredeleniya mehanicheskih svoystv metallov vdavlivaniem, Izmeritelnaya tehnika, 1982, nomer 5, USSR, ISSN 0368-1025]. Napetschnig [US 4 245 496 (Napetschnig) 20.01.1981] proposes a vertical positioning of the flexible arm. In Fohey [U.S. Pat. No. 4,182,164 (Fohey) January 8, 1980], a short displacement measuring circuit is realized, where only the indentor and the indentor are loaded, which is the lowest number of elements found between the sensor and the indentor that are deformed. Borgersen [US 4 312 220 (Borgersen) January 26, 1982] leverages the load parameter reading.

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The essence of the technical solution

The aforementioned drawbacks are largely eliminated by an instrumented indentor indentation parameter measurement system comprising a test specimen loading mechanism and a measuring device provided with a displacement sensor and a load transducer according to the present invention. The essence of this is that the measuring device comprises a housing in which a spring adapter and a displacement sensor are provided with a strain gauge and a deformation strip and a load sensor provided with deformation tapes, a cylinder and a rod extending from the indentor located in the holder to the displacement sensor, it has a lid and an acoustic emission sensor for measuring the acoustic signal that is registered by the analogue amplifier and stored in the computer.

The loading mechanism can be a Brinell, Vickers, Rockwell hardness tester, a universal tearing machine, a lever mechanism with its own load source or a piezoelectric element.

The measuring system is based on automatic indentor indentation, which has a reliable, easy to manufacture and operable adapter for measuring the main indentation parameters, such as load (P) and depth (h). Due to its design, the measuring device does not load the displacement sensor, designed to record depth indications (h) during indentor indentation, and allows recording of indentation parameters (mV) with greater accuracy compared to devices that have a longer measuring circuit. The measuring device is compact and can be used in conjunction with a variety of measuring systems, such as a tearing machine and a hardness tester, thus extending their capabilities and optimizing the indentation process. Determination of mechanical properties is based on indentation parameters. Various indentors are available, such as Brinell, Vickers, Knoop, Berkovich, Rockwell. The graphical dependence of the load depth indicates the deformation behavior of the material during the load cycle.

The load transducer is a replaceable dynamometer that contains deformation tapes for measuring small load values, larger load values are measured with a stiffer dynamometer element, cylinder. By increasing the total deformation range measured by the load cell by the deformation strips, the strain level of the strain gauge sensors is increased and thus the detection accuracy of the low load values, which allows to increase the recording frequency of the registered signal (mV) at the same sensitivity of the measuring elements, strain gauge sensors. Load sensors of several types have been developed to optimize the process of measuring load values during indentation.

The measurement system allows continuous measurement of electrical signals (mV), which corresponds to changes in measured depth of indentation (h) and applied load (P) values during indentation, where the hardness number is evaluated according to load-depth and stress-strain dependencies obtained from registered signals. other mechanical properties such as modulus of elasticity, yield strength, breaking strength, as well as elastic and plastic energy, reinforcement exponent, grain size.

Explanation of the drawings in the drawings

The technical solution will be described in more detail on a specific embodiment with the aid of the attached drawings. FIG. 1 is an exemplary instrumented measuring system. FIG. 2 shows an exemplary measuring device. FIG. 3 illustrates the location of the acoustic emission sensor in the housing cover. FIG. 4 (a) illustrates a variation of the load of the measuring device using a hardness tester. FIG. 4 (b) illustrates a variation of the load of the measuring device by means of a tearing machine. FIG. 4 (c) illustrates a variant load of the measuring device by means of a piezoelectric element. FIG. 4 (d) illustrates a variant load of the measuring device by means of a lever-operated load mechanism. FIG. 5 illustrates a typical load-depth indentation curve that includes load values (N) and depths (mm).

Examples of technical solutions

The objectives and advantages of the present technical solution are described in detail in the following text and supplemented with pictorial documentation.

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The instrumented measuring system comprises a computer 1, an analog signal amplifier 2, a test sample 3, a measuring device 4 and a loading mechanism 5. The measuring device comprises a housing 6, an adapter 7, a spring 8, a capsule 9, a strain gauge 10, a deformation strip 11, a lever 12, dynamometer 13, deformation strip 14, cylinder 15, rod 16, indent holder 17, indentor 18, housing cover 19, acoustic emission sensor 20, test sample 21.

FIG. 4 there are shown various load variants of the measuring device 4 by means of a hardness tester 26, a tearing machine 27, a piezoelectric element 28 and by a lever transmission load mechanism 30.

FIG. 5, a typical load-depth indentation curve is shown that includes load values (N) and depths (mm).

As shown in FIG. 1, the measuring system is designed to perform an indentation test and includes a test sample 3 tested by a measuring device 4 that generates signals during the indentation process at a load generated by the load mechanism 5 registered by the analog signal amplifier 2 and stored in the computer 1.

As documented in FIG. 2, when the load is applied to the adapter 7 by the loading mechanism 5, the adapter 7 begins to move in the housing 6 of the measuring device 4. The housing 6 is pressed against the sample 21 by the lid 19 with the spring 8. The load is further transferred from the adapter 7 to the dynamometer 13 which the indentor 18 pushes the sample sample 21 through the indentor holder 17. The rod 16 moves with the indent 18 and causes the deflection strip to be deflected by the multiplier lever 12. In the initial position where the indentor 18 lies on the surface of the sample 21, the rod 16 is pressed against the indent 18 by the deformation strip 11 over the multiplier lever 12. The lever 12 has in its lower part a ball cup 22 serving to center the rod 16. The rod 16 is provided with a guide lip which limits its axial movement, thereby protecting the contents of the capsule 9 and preventing the rod 16 from falling out during the replacement of the indent 18.

At the beginning of the indentation process, in the low load area, the deformation strips 14 of the dynamometer 13 deform first elastically, then the elastic deformation is transferred to the stiffer dynamometer element 13 - cylinder 15. The basket type dynamometer strips 14, which are in a more deformed state than cylinder 15, increase the discretion of the signal generated by the strain gauges 10, thereby achieving greater accuracy in measuring small loads. The larger loads are then registered by the tensometric sensors 10 of the roller 15. The signal generated by the strain gauges 10 is recorded by the analog signal amplifier 2 and stored in the computer 1. The opening at the top of the dynamometer 13 serves to position the capsule 9 and provides the necessary space for moving parts of the measuring device 4 during the indentation process. Another modification of dynamometer 13 is a cylindrical dynamometer, which has a simpler design and is intended mainly for measuring larger loads. The strain gauge sensors 10 are in this case located on its outer surface.

The displacement sensor capsule 9 is intended not only to measure the displacement of the indent 18 and to prevent mechanical damage to its contents, but also to capture the dynamometer 13 even after the measuring device 4 has been unloaded and during the replacement of the inductor 18. The capsule 9 is a separate element of the measuring device 4, providing easy access to its content, repair or replacement in case of damage. The strain gauge sensor signal 10 connected to the Π deformation tape. the lever type is generated by deflection of the deformation tape H by the applied load and is continuously registered by the analog signal amplifier 2 and stored in the computer 1. The deformation tape 11 pressed by the lever 12 to the upper part of the capsule 9 by means of the rod 16 serves to increase the discretion of the signal generated by the strain gauge 10 which are connected to the deformation tape U_. The ball cup 22 on the underside of the lever serves to center the bar 16. Using the proposed lever system of the capsule 9, the accuracy of measuring the small feeds of the indent 18 during the test is increased.

The measuring device also includes an acoustic emission sensor 20, thereby extending its capabilities. For example, determining the load parameters that correspond to limit states and material failure are not always possible when studying the properties of systems as a substrate / coating. This problem is solved by the present solution by recording an acoustic emission signal (mV) during the indentation that is generated by the test material 21 when the limit states are reached and is registered by the analog signal amplifier 2 and stored in the computer 1. During the indentation, the acoustic signal may be generated by material failure

Or in the course of its phase transformations. The acoustic emission sensor 20 is located on the deformation strip 12 in the displacement sensor capsule 9 directly above the spherical cup 22. The acoustic emission sensor 20 is located in the housing cover 19 of the measuring device 4 to increase its sensitivity to processes running under the indentor 18 in the material 21 being examined.

The measuring system is used together with a loading mechanism 5 which is connected to the measuring device 4 by means of an adapter 7. In FIG. 4 (a), a variant of the use of a hardness tester 26 as a loading mechanism 5 is shown. 4 (b) shows a variant of the use of a tear machine 27 as a loading mechanism 5. In FIG. 4 (c), a variant of the use of piezoelectric element 28 as a loading mechanism 5 is shown. Fig. 4 (d) shows a variant of a load mechanism 5 with a lever transmission 29. As an actual load mechanism 30, e.g. an electric motor can be used.

Industrial usability

The measuring system for non-destructive indentor testing by this technical solution can be used in test rooms, laboratories and the like.

Claims (2)

PROTECTION REQUIREMENTS A measuring system for inductor indentation non-destructive testing, comprising a load mechanism (5) of a test sample (3) and a measuring device (4) provided with a displacement sensor (9) and a load sensor (13), characterized in that the measuring device (4) comprising a housing (6) housing an adapter (7) with a spring (8) and a displacement sensor (9) provided with a strain gauge sensor (10) and a deformation strip (11) and a load sensor (13) provided with deformation stripes (14), a cylinder (15) and a rod (16) extending from the indentor (18) disposed in the holder (17) to the displacement sensing (9), the housing having a lid (19) and an acoustic emission sensor (20) for measuring the acoustic signal; saving it to a computer (1). The measuring system according to claim 1, characterized in that the loading mechanism (5) consists of a Brinell, Vickers, Rockwell hardness tester (26), a universal tear-off machine (27), a lever mechanism (29) with its own load source or piezoelectric element (28).