Study of the dynamic hardness of structural metal materials

2020 ◽  
Vol 86 (1) ◽  
pp. 57-61
Author(s):  
Aleksandr V. Ilinskiy ◽  
Alexey V. Fedorov ◽  
Ksenia A. Stepanova ◽  
Igor U. Kinzhagulov ◽  
Igor O. Krasnov
Keyword(s):  
Comparative Analysis ◽  
Standard Deviation ◽  
Energy Approach ◽  
Metallic Materials ◽  
Sample Standard Deviation ◽  
Dynamic Indentation ◽  
Dynamic Hardness ◽  
Structural Metal ◽  
Metal Materials ◽  
Hardness Values

The mechanical properties of structural metallic materials are the most important indicators of their quality. Different methods (i.e., the methods of Shore, Brinell, Rockwell, Leeb, Vickers, method of instrumental indentation, and others) are currently used for determination of the hardness — one of the most important mechanical characteristics of structural metal materials. Among them is the method of dynamic indentation first developed at the Institute of Applied Physics of the National Academy of Sciences of Belarus. With the goal of further developing of the method of dynamic indentation, we propose the procedures aimed at increasing the accuracy of assessing the hardness of structural metallic materials: parameters of the contact interaction of the indenter with the sample material (Brinell hardness values) were measured using a dynamic indentation (DI) device; the values of surface and volumetric dynamic hardness were calculated taking into account the characteristics obtained using a DI device; a comparative analysis of hardness estimates obtained by different approaches was carried out. As a result of the comparative analysis of the methods, as well as their experimental testing, it was shown that an increase in the accuracy of hardness assessment can be achieved by using the «energy» approach based on assessing the ratio of the total work to the volume of the recovered indentation upon dynamic indentation of structural metal materials. The use of the «energy» approach provided obtaining the sample standard deviation of the volumetric dynamic hardness values, which, in turn, was significantly lower than the sample standard deviation of the surface dynamic hardness values and data of the dynamic indentation device, which directly affects an increase in the accuracy of hardness estimation during dynamic indentation of structural metal materials. Proceeding from the «energy» approach, a new algorithm for processing the initial signal is proposed when the dynamic hardness is determined using a dynamic indentation device.

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.

Nucleic Acid Molecules Prepared by Monolayer Techniques

1972 ◽  
Vol 30 ◽  
pp. 178-179
Author(s):  
Dimitrij Lang
Keyword(s):  
Electron Microscopy ◽  
Standard Deviation ◽  
Nucleic Acid ◽  
Cytochrome C ◽  
Nucleic Acids ◽  
Contour Length ◽  
Sample Standard Deviation ◽  
Molecular Weights ◽  
Length Measurements ◽  
Protein Monolayer

The success of the protein monolayer technique for electron microscopy of individual DNA molecules is based on the prevention of aggregation and orientation of the molecules during drying on specimen grids. DNA adsorbs first to a surface-denatured, insoluble cytochrome c monolayer which is then transferred to grids, without major distortion, by touching. Fig. 1 shows three basic procedures which, modified or not, permit the study of various important properties of nucleic acids, either in concert with other methods or exclusively:1) Molecular weights relative to DNA standards as well as number distributions of molecular weights can be obtained from contour length measurements with a sample standard deviation between 1 and 4%.

Comparative Analysis of the Exposure and Surgical Freedom of the Endoscopic Extended Minipterional Craniotomy and the Transorbital Endoscopic Approach to the Anterior and Middle Cranial Fossae

2018 ◽  
Vol 17 (2) ◽  
pp. 174-181 ◽  
Author(s):  
Raywat Noiphithak ◽  
Juan C Yanez-Siller ◽  
Juan M Revuelta Barbero ◽  
Raymond I Cho ◽  
Bradley A Otto ◽  
...  
Keyword(s):  
Comparative Analysis ◽  
Standard Deviation ◽  
Minimally Invasive ◽  
Vertical Axis ◽  
Endoscopic Approach ◽  
Extended Version ◽  
Specific Approach ◽  
Significant Difference ◽  
Surgical Application ◽  
The Mean

AbstractBACKGROUNDNumerous minimally invasive approaches to the skull base have been successively developed. Knowledge of the surgical nuances of a specific approach may facilitate approach selection. This study sought to compare the nuances of an extended version of the minipterional craniotomy (EMPT) with those of the transorbital endoscopic approach (TOEA) to the anterior and middle cranial fossae (ACF and MCF, respectively).OBJECTIVETo quantitatively analyze and compare the area of exposure and surgical freedom between EMPT and TOEA to the ACF and MCF.METHODSEMPT and TOEA were carried out in 5 latex-injected cadaveric heads, bilaterally (10 sides). For each approach, the area of exposure, surgical freedom, and angle of attack were obtained with neuronavigation and statistically compared.RESULTSNo significant difference was found between the mean area of exposure of EMPT and TOEA at the ACF and MCF (P = .709 and .317, respectively). The mean exposure area at the ACF was of 13.4 ± 2.6 cm2 (mean ± standard deviation) and 13.0 ± 1.9 cm2 for EMPT and TOEA, respectively. Except for the crista galli, EMPT afforded a larger area of surgical freedom at all targets. EMPT also achieved significantly greater attack angles in vertical axis except to the crista galli. The horizontal attack angles to all targets were similar between approaches.CONCLUSIONEMPT and TOEA offer a comparable area of exposure at the ACF and MCF in the cadaver; however, the instrument maneuverability afforded by EMPT is superior. Further studies are necessary to better define their precise surgical application.

Effects of dynamic indentation on the mechanical response of materials

2008 ◽  
Vol 23 (6) ◽  
pp. 1604-1613 ◽  
Author(s):  
M.J. Cordill ◽  
N.R. Moody ◽  
W.W. Gerberich
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Mechanical Response ◽  
Length Scale ◽  
Polycrystalline Nickel ◽  
Dynamic Indentation ◽  
Crystalline Materials ◽  
Fused Quartz ◽  
Hardness Values ◽  
Measured Hardness

Dynamic indentation techniques are often used to determine mechanical properties as a function of depth by continuously measuring the stiffness of a material. The dynamics are used by superimposing an oscillation on top of the monotonic loading. Of interest was how the oscillation affects the measured mechanical properties when compared to a quasi-static indent run at the same loading conditions as a dynamic. Single crystals of nickel and NaCl as well as a polycrystalline nickel sample and amorphous fused quartz and polycarbonate have all been studied. With respect to dynamic oscillations, the result is a decrease of the load at the same displacement and thus lower measured hardness values of the ductile crystalline materials. It has also been found that the first 100 nm of displacement are the most affected by the oscillating tip, an important length scale for testing thin films, nanopillars, and nanoparticles.

Alveolar pressure inhomogeneity during low-frequency oscillation of excised canine lobes

1990 ◽  
Vol 69 (1) ◽  
pp. 155-161 ◽  
Author(s):  
D. O. Warner
Keyword(s):  
Standard Deviation ◽  
Lung Volume ◽  
Vital Capacity ◽  
Low Frequency ◽  
Absolute Amount ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Sample Standard Deviation ◽  
Time Constants ◽  
Cyclic Changes

To quantify the inhomogeneity of alveolar pressures (PA) during cyclic changes in lung volume similar to those present during spontaneous breathing, inhomogeneity of PA was measured with an alveolar capsule technique in six excised canine lungs. The lungs were ventilated by a quasi-sinusoidal pump with a constant end-expiratory lung volume and tidal volumes of 10, 20, and 40% of vital capacity at breathing frequencies ranging from 5 to 45 breaths/min. Inhomogeneity of PA was quantified as the sample standard deviation of pressures measured in three capsules. A component of inhomogeneity in phase with flow and a smaller component out of phase with flow were present. The in-phase component increased approximately linearly with flow. The ratio of inhomogeneity to flow was smaller at large tidal volumes and, at the two higher tidal volumes studied, the ratio was greater during inspiration than during expiration. If these data are interpreted in terms of a simple circuit model, this degree of inhomogeneity implies an approximately twofold variation in regional time constants. Despite these considerable differences in time constants, the absolute amount of inhomogeneity as defined by the sample standard deviation of the three PA's was small (maximum 0.57 +/- 0.32 cmH2O at the highest breathing frequency and tidal volume) because airway resistance in the canine lung was small.

An investigation into the dynamic indentation response of metallic materials

2016 ◽  
Vol 51 (18) ◽  
pp. 8310-8322 ◽  
Author(s):  
Jian Chen ◽  
Xiangru Shi ◽  
Ben D. Beake ◽  
Xinli Guo ◽  
Zengmei Wang ◽  
...  
Keyword(s):  
Metallic Materials ◽  
Dynamic Indentation ◽  
Indentation Response

The Use of Downton’s Estimator in Dual Response Surface Optimization

2012 ◽  
Author(s):  
Chuan Kim Ch’ng ◽  
Boon Chong Michael Khoo
Keyword(s):  
Standard Deviation ◽  
Response Surface ◽  
Mean Squared Error ◽  
Extreme Points ◽  
Robust Estimator ◽  
Sample Standard Deviation ◽  
Response Surface Optimization ◽  
Squared Error ◽  
Dual Response ◽  
Surface Optimization

Kaedah sambutan dual terdiri daripada dua sambutan bagi suatu cirian kualiti. Dua sambutan tersebut ialah sambutan min dan sambutan sisihan piawai (varians) yang dianggarkan daripada reka bentuk eksperimen selepas penyuaian model dijalankan. Sambutan sisihan piawai biasanya dianggar daripada sisihan piawai sampel. Kelemahan utama penganggar yang berdasarkan sisihan piawai sampel adalah ia mudah dipengaruhi oleh titik ekstrim. Bagi kes sedemikian, model yang tersuai berdasarkan sisihan piawai sampel adalah mungkin tidak jitu. Oleh itu, penggunaan pendekatan ini mungkin tidak dapat memberi titik kompromi yang betul. Dalam kertas kerja ini, suatu anggaran sisihan piawai berdasarkan penganggar Downton dicadangkan dalam pengoptimuman kaedah sambutan dual. Penganggar teguh kurang dipengaruhi oleh titik ekstrim berbanding dengan sisihan piawai sampel. Dalam hal ini, suatu model tersuai yang berdasarkan penganggar teguh akan memberikan keputusan yang lebih baik. Suatu contoh digunakan untuk mengilustrasikan kecekapan cadangan kami dalam pengoptimuman. Dalam contoh ini ralat kuasadua min (MSE) akan digunakan sebagai ciri pengoptimuman. Kata kunci: Penganggar Downton, pengoptimuman sambutan dual, ralat min kuasa dua, pengoptimuman, titik kompromi A dual response surface approach consists of two responses of a quality characteristic. These two responses are the mean response and the standard deviation (variance) response, which are estimated from an experimental design after performing a model fitting. The standard deviation response is usually estimated using the sample standard deviation. The main drawback of this estimator by means of sample standard deviation is that it is easily influenced by extreme points. For this case, the fitted model based on the sample standard deviation may not be accurate. Thus, the use of this approach may not produce the correct compromised setting. In this paper, an estimation of the standard deviation based on Downton’s estimator in a dual response surface optimization is proposed. A Downton estimator is a robust estimator of standard deviation. A robust estimator is less affected by extreme points compared to the sample standard deviation. Here, a model based on a robust estimator will give better results. An example is used to illustrate the effectiveness of our proposal in optimization. In this example, mean squared error (MSE) will be used as the optimization criterion. Key words: Downton’s estimator, dual response surface optimization, mean squared error, optimization, compromise setting

A non-contact method for determining the junction temperature of GaN-based blue light LED

2017 ◽  
Vol 31 (19-21) ◽  
pp. 1740023
Author(s):  
Guo Jie ◽  
Junshan Ma ◽  
Rao Feng
Keyword(s):  
Comparative Analysis ◽  
Standard Deviation ◽  
Blue Light ◽  
Junction Temperature ◽  
Contact Method ◽  
Forward Voltage ◽  
Spectral Parameters ◽  
Blue Led ◽  
Novel Method

A novel method to determine the junction temperature of GaN type blue light LED based on the spectral parameters is proposed. In this method, the relationships among LED junction temperature, centroid wavelength and FWHM are obtained in the lab, and then the junction temperature of operating LED of the same type can be derived from this relationship. A comparative analysis of the junction temperatures which are measured with the centroid wavelength-FWHM method and with the forward voltage method is performed. The standard deviation between these two methods is found to be about 2.3[Formula: see text]C. Therefore, the combination of centroid wavelength and FWHM can be used to determine the junction temperature of GaN-based blue LED.

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