scholarly journals Evaluation of the error of indirect measurements of physical-mechanical characteristics of materials by dynamic indentation method

2020 ◽  
Vol 65 (4) ◽  
pp. 487-495
Author(s):  
O. V. Matsulevich ◽  
A. P. Kren ◽  
T. A. Pratasenia ◽  
M. N. Delendik
Keyword(s):  
Elastic Modulus ◽  
Measurement Error ◽  
Mechanical Characteristics ◽  
Experimental Studies ◽  
Strain Hardening Exponent ◽  
Dynamic Indentation ◽  
Indentation Method ◽  
Indirect Measurements ◽  
Accuracy Of Measurements ◽  
Wide Range

The metrological problems of measuring the physic and mechanical characteristics of materials by dynamic indentation are considered. It is shown that the estimation of measurement error demanding the creation of the reference blocks is ineffective due to the wide variety of controlled materials and a wide range of changes in their properties. A technique has been developed for evaluating the accuracy of measurements based on the errors of individual parameters included in the calculation equation, i.e. by determining the error of indirect measurements. The technique is based on the estimation of the boundaries of the random error of the measured characteristics of the material and the non-excluded systematic errors of the parameters that are used for the calculations of needed characteristics. The results of experimental studies are presented, indicating that due to the different character of the dependencies of hardness and elastic modulus, the error in measuring the elastic modulus exceeds the error in measuring hardness. In addition, it was found that the error in measuring the characteristics of materials by the dynamic indentation method exceeds the measurement error by the static indentation method and can be reduced by increasing the accuracy of the equipment used for the registration of impact process. The obtained values of the physic and mechanical characteristics of the materials and the values of the measurement error show that the dynamic indentation method can effectively solve the problem of non-destructive testing of hardness, elastic modulus, and strain hardening exponent of metals and products with an appropriate error.

scholarly journals Error estimation of the physical and mechanical characteristics measurements by indentation

2018 ◽  
Vol 9 (3) ◽  
pp. 263-271
Author(s):  
A. P. Kren ◽  
O. V. Matsulevich ◽  
M. N. Delendik
Keyword(s):  
Measurement Error ◽  
Error Estimation ◽  
Evaluation System ◽  
Mechanical Characteristics ◽  
Physical And Mechanical Properties ◽  
Strain Hardening Exponent ◽  
Indirect Measurements ◽  
Static Indentation ◽  
Indentation Methods ◽  
Physical And Mechanical Characteristics

The active application in the practice of testing the indentation methods, in particular to measure the physical and mechanical properties of metals, polymers, biological technologies demands to development techniques for the measurement error estimation. At the same time existing traditional measurement error evaluation system, based on the using of the reference blocks, is not always suitable for use in testing and research laboratories. The aim of this work was development the technique for estimating the indirect measurements error of materials physical and mechanical characteristics that can be applied in practice and based on the existing standards. Checking of the proposed approach using the experimental values of the hardness and elastic modulus obtained during static indentation for various metals.It is shown that since the initial information about the material is an indentation curve representing the dependence of the load versus penetration depth of the indenter into the material tested, then it is better to confirm the metrological characteristics of the indentation measuring devices using the applied force and achieved displacement, but to estimate the accuracy of determining the properties through the error of indirect measurements. The equations for calculating the hardness and modulus of elasticity are derived. It allows to determine the component value most influencing the error magnitude. The calculation of error on the base of the value of boundary of a random and non-exclusive systematic error was carrying out.The advantage of the developed technique is the fact that the measurement of the physical and mechanical characteristics is based on the experimental data and does not require the creation of the additional metrological assurance. The proposed approach seems appropriate to extend for the determination of the measurement error of other characteristics: the yield point, the strain hardening exponent, creep, relaxation, determined by the indentation methods.

scholarly journals Peculiarities of structure state and mechanical characteristics in ion-plasma condensates of quasibinary system borides W2B5-TiB2

2006 ◽  
Vol 38 (1) ◽  
pp. 63-72 ◽  
Author(s):  
O.V. Sobol ◽  
O.N. Grigoryev ◽  
YU.A. Kunitsky ◽  
S.N. Dub ◽  
A.A. Podtelezhnikov ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Mechanical Characteristics ◽  
Hexagonal Lattice ◽  
Element Composition ◽  
Cubic Lattice ◽  
Ion Plasma ◽  
Nano Crystalline ◽  
Wide Range ◽  
Quasibinary System ◽  
Structure State

In order to create high-durable, wear-resistant materials for a wide range of functional applications, comparative investigations of the structure and mechanical characteristics of ion-plasma Ti-W-B nano-crystalline condensates were carried out. The range of condensation rates 0.11?0.25nm/s was found to be critical for the coatings obtained from the target with 80 vol% W2B5-20 vol% TiB2. Below this, a phase with a cubic lattice (W,Ti)B0.7?1.2(O,N,C)0.3?0.2 formed, while over this range, a solid solution (W,Ti)B2 with a hexagonal lattice and element composition close to the sputtered target was observed. The structure state of the material changed from cluster-crystalline (under low sputter potentials U=0.6?1.0 kV) to textured- crystalline (under U>2.2 kV). Structure perfection improvement with U increase results in higher hardness and elastic modulus of condensates. The conditions of cluster component formation and its effect on hardness and elastic modulus of condensates are discussed. .

scholarly journals EVALUATION OF METALLIC MATERIALS PLASTICITY BY DYNAMIC INDENTATION METHOD

2017 ◽  
pp. 81-87 ◽  
Author(s):  
V. A. Rudnitsky ◽  
A. P. Kren ◽  
G. A. Lantsman
Keyword(s):  
Elastic Modulus ◽  
Metallic Materials ◽  
Dynamic Indentation ◽  
Indentation Method ◽  
Dynamic Hardness

The method of plasticity test of metallic materials realized by means of a dynamic dimpling of material by a spherical tip is offered. The measured value of plasticity is defined by a ratio of plastic and complete deformations in the formed indentation which considers influence of an elastic modulus of material. The dependence connecting plasticity and dynamic hardness of materials is received. Experiments on metals from 70 to 380 GPA having an elastic modulus and hardness up to 62 HRC are made.

scholarly journals Diagnostics of steel structures with the dynamic non-destructive method

2019 ◽  
Vol 279 ◽  
pp. 02003 ◽  
Author(s):  
Alexey Beskopylny ◽  
Andrey Veremeenko ◽  
Alexander Shilov
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Mechanical Characteristics ◽  
Steel Structures ◽  
Dynamic Indentation ◽  
Lower Strength ◽  
Indentation Method ◽  
Element Analysis ◽  
Railway Bridges ◽  
Non Destructive

The method of the assessment of steel structures mechanical properties is considered with the nondestructive test by conical indentation. The nondestructive evaluating of the steel mechanical properties in real structures is widely spread in many applied problems. Dynamic indentation method is one of the most effective because of compatibility and accuracy. For this purpose, the static and dynamic problem of axisymmetric elastic-plastic truncated cone indentation is solved, and the results are compared with finite element analysis and experimental data. The method of nondestructive evaluating of mechanical characteristics is suggested and devise of the realization of the method is tested at real structures. The method is tested on steel railway bridges that are being operated for more than 60 years. As a result, zones with lower strength values were identified, and recommendations for strengthening the design were given.

Evaluation of the accuracy indicators in determination of the coating thickness by crater grinding method

2020 ◽  
Vol 86 (7) ◽  
pp. 39-44
Author(s):  
K. V. Gogolinsky ◽  
A. E. Ivkin ◽  
V. V. Alekhnovich ◽  
A. Yu. Vasiliev ◽  
A. E. Tyurnina ◽  
...  
Keyword(s):  
Coating Thickness ◽  
Functional Dependence ◽  
Measurement Procedure ◽  
Metrological Certification ◽  
Measuring Instruments ◽  
Properties Of Coatings ◽  
Special Equipment ◽  
Grinding Method ◽  
Accuracy Of Measurements ◽  
Wide Range

Thickness is one of the key indicators characterizing the quality and functional properties of coatings. Various indirect methods (electromagnetic, radiation, optical) most often used in practice to measure thickness are based on the functional dependence of a particular physical parameter of the system «base – coating» on the coating thickness. The sensitivity of these procedures to the certain properties of coatings imposes the main restriction to the accuracy of measurements. Therefore, the development and implementation of the approaches based on direct measurements of geometric parameters of the coating appears expedient. These methods often belong to the class of «destructive» and, in addition to measuring instruments, require the use of special equipment. To ensure the uniformity of measurements in the laboratory or technological control, these methods are isolated as a separate procedure (method) and must undergo metrological certification in accordance with GOST R 8.563–2009. We present implementation, metrological certification and practical application of the method for measuring thickness of coatings by crater-grinding method. The principles of technical implementation of test equipment, measurement procedure and calculation formulas are described. The results of evaluating the accuracy indicators of the proposed procedure by calculation and experimental methods are presented. In both cases, the relative error did not exceed 6%. The applicability of the developed technique is shown for a wide range of coating materials (from soft metals to superhard ceramics) of different thickness (with from units to hundreds of micrometers). Apart from the goals of process control and outgoing inspection, the method can be recommended as a reference measurement procedure for calibration of measures and adjusting samples for various types of thickness gauges.

scholarly journals Image Statistics Preserving Encrypt-then-Compress Scheme Dedicated for JPEG Compression Standard

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 421
Author(s):  
Dariusz Puchala ◽  
Kamil Stokfiszewski ◽  
Mykhaylo Yatsymirskyy
Keyword(s):  
Statistical Analysis ◽  
Image Encryption ◽  
Experimental Studies ◽  
Quality Measures ◽  
Input Image ◽  
Jpeg Compression ◽  
Image Statistics ◽  
Compression Stage ◽  
Wide Range ◽  
The Impact

In this paper, the authors analyze in more details an image encryption scheme, proposed by the authors in their earlier work, which preserves input image statistics and can be used in connection with the JPEG compression standard. The image encryption process takes advantage of fast linear transforms parametrized with private keys and is carried out prior to the compression stage in a way that does not alter those statistical characteristics of the input image that are crucial from the point of view of the subsequent compression. This feature makes the encryption process transparent to the compression stage and enables the JPEG algorithm to maintain its full compression capabilities even though it operates on the encrypted image data. The main advantage of the considered approach is the fact that the JPEG algorithm can be used without any modifications as a part of the encrypt-then-compress image processing framework. The paper includes a detailed mathematical model of the examined scheme allowing for theoretical analysis of the impact of the image encryption step on the effectiveness of the compression process. The combinatorial and statistical analysis of the encryption process is also included and it allows to evaluate its cryptographic strength. In addition, the paper considers several practical use-case scenarios with different characteristics of the compression and encryption stages. The final part of the paper contains the additional results of the experimental studies regarding general effectiveness of the presented scheme. The results show that for a wide range of compression ratios the considered scheme performs comparably to the JPEG algorithm alone, that is, without the encryption stage, in terms of the quality measures of reconstructed images. Moreover, the results of statistical analysis as well as those obtained with generally approved quality measures of image cryptographic systems, prove high strength and efficiency of the scheme’s encryption stage.

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