scholarly journals Precision analysis of forced-oscillation device: numerical modelling and experimental investigations

2020 ◽  
Vol 17 (6) ◽  
pp. 980-992
Author(s):  
Hui Li ◽  
Jing Lin ◽  
Jinghuai Gao ◽  
Yanbin He ◽  
Dehua Han ◽  
...  
Keyword(s):  
Stress State ◽  
Forced Oscillation ◽  
Simulated Data ◽  
Static Friction ◽  
Experimental Investigations ◽  
Frequency Dependent ◽  
Large Measurement ◽  
Solid Foundation ◽  
Large Measurement Error ◽  
Elastic Characteristics

Abstract Investigating the stress state of a sample-standard column in forced-oscillation apparatus is critical to clearly quantify measurement credibility, offering insights into revealing intrinsic frequency-dependent elastic characteristics of a rock sample. To investigate the effects of the jointing condition, the location of strain gauges and device resonance on the stress state of a sample-standard column, we experiment with a typical forced-oscillation setup numerically and experimentally at frequencies of 2–800 Hz. Overall, the numerical model captures the primary features of the forced-oscillation device, which makes the simulated data fit well with the measured results. Meanwhile, based on the configuration of the sample-standard column with variable static friction in jointing contacts, the simulated results also indicate that mechanical contacts of the sample-standard-vibrator assembly lead to stress concentration, resulting in coordinate-dependent strains on both the sample and standard. Additionally, strain magnitude is also frequency-dependent, causing a relatively large measurement error on the elasticity of the sample at higher frequencies. Ultimately, numerical results not only optimize measurement workflow but also create a solid foundation for the interpretation of measured data.

Theoretical and experimental investigations of the stress state of elastic cylinders with grooves

1983 ◽  
Vol 19 (10) ◽  
pp. 862-866
Author(s):  
Yu. N. Nemish ◽  
Yu. I. Vologzhaninov ◽  
A. I. Zirka ◽  
N. M. Bloshko
Keyword(s):  
Stress State ◽  
Experimental Investigations ◽  
Elastic Cylinders

The Association of Stock Distribution Announcements and Earnings Performance

1988 ◽  
Vol 3 (2) ◽  
pp. 113-132 ◽  
Author(s):  
David T. Doran ◽  
Robert Nachtmann
Keyword(s):  
Forecast Error ◽  
Control Sample ◽  
Earnings Forecasts ◽  
Earnings Expectations ◽  
Future Earnings ◽  
Earnings Information ◽  
Unexpected Earnings ◽  
Large Measurement ◽  
Stock Dividends ◽  
Large Measurement Error

This paper analyzes the association of unexpected earnings with stock dividend and stock split announcements. Unexpected earnings are modeled as the percentage deviation of actual earnings from expected. Value Line's earnings forecasts are used as a surrogate for the market's timely expectation of future earnings. The primary findings are: (1) postdistribution earnings realizations are greater than expected; and (2) deviations of realized earnings from expected are (a) directly related to the size of the stock distribution and (b) inversely related to the level of market anticipation of the event. Further, distribution size may be a proxy for market anticipation in that small distributions (stock dividends) are dominated by anticipated events and large distributions (stock splits) by unanticipated events. These findings are robust across samples that control for large measurement error due to small levels of forecasted earnings, and event contamination due to the simultaneous announcement of firm-related events. Examination of analysts' forecasts immediately following the event indicates a significant upward revision in earnings expectations. This finding, coupled with an analysis of a control sample of Value Line earnings forecasts, indicates that the observed unexpected earnings are not the result of systematic Value Line forecast error. Therefore, the paper provides support for the notion that stock distribution announcements convey future earnings information.

Geklebte Schneidsegmente im unterbrochenen Schnitt*/Adhesively bonded cutting segments in intermittent cutting – Examples for their application in circular sawing of aluminum

2018 ◽  
Vol 108 (06) ◽  
pp. 466-472
Author(s):  
M. Stroka ◽  
F. Schumpp ◽  
M. Schneider
Keyword(s):  
Stress State ◽  
Experimental Investigations ◽  
Turning Process ◽  
Adhesively Bonded ◽  
The Real ◽  
Circular Saw ◽  
Circular Sawing ◽  
Sawing Process ◽  
Intermittent Cutting ◽  
Model Approach

Der Beitrag stellt Untersuchungen zu geklebten Schneidsegmenten für Kreissägeanwendungen vor. Die tatsächliche Beanspruchung des Sägeprozesses wird dabei durch einen Modellversuch abgebildet, der den Sägeprozess auf einen Drehprozess mit unterbrochenem Schnitt überträgt. So können mit geringem Aufwand vereinfachte, geklebte Proben in der Zerspanung anwendungsbezogen untersucht werden. Die Versuche wurden mit hartmetallbestückten Proben an Aluminiumwerkstücken durchgeführt.   The article presents experimental investigations of adhesively bonded cutting segments for circular saw blades. The real stress state is reproduced by a model approach which transfers the sawing process to a turning process with intermittent cutting. This allows for easily investigating the use of adhesively bonded specimens in machining. The experiments were performed with carbide-tipped specimens on aluminum workpieces.

Improving the method for determining the dust penetration of textile materials for the human protective equipment manufacture

2020 ◽  
Vol 2 (102) ◽  
pp. 49-54
Author(s):  
A.A. Avahumian ◽  
N.M. Zashchepkina
Keyword(s):  
Road Dust ◽  
Test Sample ◽  
Measuring System ◽  
Negative Effects ◽  
Textile Materials ◽  
Information Measuring ◽  
Information Measuring System ◽  
Large Measurement ◽  
Accuracy Of Measurement ◽  
Large Measurement Error

Purpose: Improving the accuracy of determining the coefficient of dust permeability of textile materials and protective products from them. Design/methodology/approach: The problem solution of human protection from the negative effects of road dust is to improve the quality control procedures of textile materials using modern measurement methods. A methodology has been developed for investigating the dust penetration coefficient of materials based on the use of a television informationmeasuring system (TIMS). Findings: The methodology for determining the dust permeability of textile materials through the use of a television information-measuring system has been improved, by increasing the accuracy of measurement and determining the patterns of the influence of structure on the permeability of textile materials. Research limitations/implications: Improving methods of quality control of textile materials through the use of modern methods of measuring techniques is by solving an important problem of human protection from the negative effects of road dust. Known methods do not take into account the forceful effect of the airflow on the structure of the test sample, which is essential for textile materials that are easily deformed, which affects the objectivity of the results. Significant inconvenience, complexity, and duration of the test process give a large measurement error. Practical implications: The methodology for determining the dust permeability of textile materials through the use of a television information-measuring system has been improved. This system allows an increase in the accuracy of measurements by 15%, and the availability of software to increase the speed of displaying the results of investigations on the screen. Originality/value: The main disadvantages of methods and means of determining the dust permeability of textile materials - is the inability to determine the duration and dynamics of the process of dust retention. Known methods do not take into account the force of air flow on the structure of the test sample, which is significant, especially for materials that are easily deformed, which affects the objectivity of the results. Significant inconveniences, complexity and duration of the test process give a large measurement error. A scientific novelty is the development of a modern and completely new method for determining the permeability of textile materials using a television information - measuring system, by increasing the accuracy of measurement and determining the patterns of influence of the structure of textile materials on dust permeability.

scholarly journals Influence of grinding zones on the tooth root bending strength of case carburized gears

2021 ◽  
Author(s):  
Karl Jakob Winkler ◽  
Thomas Tobie ◽  
Karsten Stahl
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Bending Strength ◽  
Decisive Role ◽  
Experimental Investigations ◽  
Tooth Root ◽  
Industrial Practice ◽  
Application Range ◽  
Residual Stress State ◽  
Root Area

AbstractKnowledge of the expected tooth root bending strength plays a decisive role in the design of gear sets. Due to dimensional and shape changes resulting from distortion due to the heat treatment, unintentional, partial grinding in the tooth root area may occur, particularly in the application range of large gears. The influences of an unintentional grinding zone on the tooth root bending strength have not yet been clarified with sufficient accuracy. As a result, grinding zones lead to uncertainties when evaluating the tooth root bending strength and thus to a loss of time and cost in the field of industrial practice.This paper presents experimental investigations on the influence of grinding zones on the tooth root bending strength of case carburized gears. For the experimental investigations, there are three unground reference variants with different blasting treatments: non-blasted, mechanical cleaned by shot blasting and shot peened. The unground reference variants are examined regarding their tooth root bending strength. For the other test gear variants, different grindings zones are applied resulting in light and strong material removal by grinding. The variants with the different grinding zones are examined analogously regarding their tooth root bending strength and are subsequently compared to the reference variants.The results of the experimental investigations show that grinding zones can have diverse influences on the tooth root bending strength of case carburized gears– Non-blasted gears do not show changes regarding the tooth root bending strength with regard to light or strong grinding zones applied within this investigation.– Shot blasted (mechanical cleaned) gears show no change in the tooth root bending strength for light grinding zones (grinding application does not significantly alter the original residual stress state in the tooth root area).– Shot blasted (mechanical cleaned) gears show a reduction of the tooth bending strength of up to 20 % with regard to strong grinding zones (grinding application does significantly alter the original residual stress state in the tooth root area).– Shot peened gears show a behavior similar to that of shot blasted gears with reductions of the tooth root bending strength of up to 30 %.– Shot peening the strong grinding zones as a repair measure can increase the reduced tooth root bending strength again. However, for the investigated test gears, the resulting tooth root bending strength was below the shot blasted reference variant.The results of this paper help to evaluate the influence of grinding zones on the tooth root bending strength of case carburized gears more precisely compared to the generalized reductions of current standards and classifications. The results can be incorporated in standards such as DIN 3390 as well as ISO 6336 and can be applied in the field of industrial practice. Eventually, the findings help to reduce the current loss of time and cost caused by uncertainties regarding grinding zones.

Three-dimensional numerical modelling of the drained/undrained transition for frequency-dependent elastic moduli and attenuation

2019 ◽  
Vol 219 (1) ◽  
pp. 27-38 ◽  
Author(s):  
Chao Sun ◽  
Genyang Tang ◽  
Jianguo Zhao ◽  
Liming Zhao ◽  
Teng Long ◽  
...  
Keyword(s):  
Numerical Model ◽  
Boundary Conditions ◽  
Elastic Moduli ◽  
Forced Oscillation ◽  
Three Dimensional ◽  
Frequency Dependent ◽  
Measurement Results ◽  
D Model ◽  
Dispersion And Attenuation ◽  
Oscillation Method

SUMMARY In fully fluid-saturated rocks, two common phenomena are documented both experimentally and theoretically for frequency-dependent elastic moduli and attenuation, that is, the drained/undrained transition and the relaxed/unrelaxed transition. When investigating these transitions with the forced oscillation method in the laboratory, it is crucial to consider the boundary differences between the laboratory and the underground. A 1-D poroelastic numerical model was previously established to describe these differences and their effects; however, the boundary conditions used in the model are actually different from the real experiment case, thus leading to inaccurate predication of the measurement results in a laboratory. In this paper, we established a 3-D poroelastic numerical model with a new set of boundary conditions that better represent the experiment conditions. Furthermore, the 3-D poroelastic modelling results were compared with laboratory measurements under the same boundary conditions, showing a much better fit than the 1-D model. Therefore, the 3-D model provides a more accurate and reliable approach to understand the regimes and transitions of elastic modulus dispersion and attenuation, and thus has great importance in interpreting the measurements of frequency-dependent properties of rocks in the laboratory.

scholarly journals Dynamic Preisach model identification applying FEM and measured BH curve

2014 ◽  
Vol 33 (6) ◽  
pp. 2043-2052 ◽  
Author(s):  
Miklós Kuczmann
Keyword(s):  
Dynamic Model ◽  
Model Identification ◽  
Simulated Data ◽  
Electrical Equipment ◽  
Field Analysis ◽  
Hysteresis Model ◽  
Frequency Dependent ◽  
Content Type ◽  
Analysis And Design ◽  
Preisach Hysteresis

Purpose – The purpose of this paper is to develop a viscous-type frequency dependent scalar Preisach hysteresis model and to identify the model using measured data and nonlinear numerical field analysis. The hysteresis model must be fast and well applicable in electromagnetic field simulations. Design/methodology/approach – Iron parts of electrical machines are made of non-oriented isotropic ferromagnetic materials. The finite element method (FEM) is usually applied in the numerical field analysis and design of this equipment. The scalar Preisach hysteresis model has been implemented for the simulation of static and dynamic magnetic effects inside the ferromagnetic parts of different electrical equipment. Findings – The comparison between measured and simulated data using a toroidal core shows a good agreement. A modified nonlinear version of TEAM Problem No. 30.a is also shown to test the hysteresis model in the FEM procedure. Originality/value – The dynamic model is an extension of the static one; an extra magnetic field intensity term is added to the output of the static inverse model. This is a viscosity-type dynamic model. The fixed-point method with stable scheme has been realized to take frequency dependent anomalous losses into account in FEM. This scheme can be used efficiently in the frame of any potential formulations of Maxwell's equations.

INFLUENCES OF AGGREGATION ON THE TWO-PHOTON FLUORESCENCE PROCESS

2013 ◽  
Vol 22 (01) ◽  
pp. 1350011 ◽  
Author(s):  
ZHIQIANG ZHOU ◽  
CHANGGUI LU ◽  
YIPING CUI
Keyword(s):  
Measurement Error ◽  
Cross Section ◽  
Correction Method ◽  
Photon Absorption ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Large Measurement ◽  
Two Photon Fluorescence ◽  
Photon Fluorescence ◽  
Large Measurement Error

Rhodamine B (RhB) is most often used as the reference in the two-photon induced fluorescence (TPIF) method to measure the two-photon absorption (TPA) cross-section. In this work, we investigate the influences of dimer formation, energy transfer and self-absorption on the two-photon fluorescence process. Those three effects will result in a large measurement error of the TPA cross-section. We thus provide a concentration gradient correction method by considering the above three processes to eliminate the measurement error.

scholarly journals Numerical and experimental assessment of the long-operated drill pipes destruction conditions

2020 ◽  
pp. 88-97
Author(s):  
O. Yu. Vytyaz ◽  
R. S. Hrabovskyi ◽  
V. I. Artym ◽  
V. V. Tyrlych ◽  
N. R. Hrabovska
Keyword(s):  
Stress Intensity ◽  
Stress State ◽  
Limit State ◽  
Drill Pipe ◽  
Crack Tip ◽  
Experimental Investigations ◽  
Technical Diagnostics ◽  
Drilling Fluids ◽  
Critical Crack ◽  
Drill Pipes

The cause of failures in the elements of the drill string when drilling deep wells is the occurrence and development of crack-like defects in the cross section. The generalized data of defectoscopy of long-term operated drill pipes conducted at the Ukrburgaz drilling rigs from 2015 to 2017, as well as numerous literature data show that such defects are formed at the bottom of corrosion ulcers that occur during operation under the influence of workloads and drilling fluids, in particular during tripping operations, both on the inner and outer surfaces of the drill pipe. During the tripping operations, under the influence of tensile loads, they being developed go up to the surface of the drill pipe, forming scouring, which ultimately leads to the destruction of the pipe. Using known analytical solutions, the stress state in the vicinity of the semieliptic crack located on both the outer and inner surfaces of the hollow cylinder under axial load was estimated and the corresponding stress intensity coefficients at the crack tip of these defects were determined. To predict the limit state of a drill pipe with a semieliptic crack, the analysis of crack parameters reflecting the local stress-strain state near the crack tip is performed. Using the finite-element method, the stress state around the vertex of the semieliptic crack was determined and on this basis the characteristics of fracture mechanics were calculated: J – integral and stress intensity coefficients. Diagrams of fracture risk assessment in the coordinates "depth of crack-like defect - depth of drilling - stress intensity factor" are offered, which make it possible to estimate the safe depth of both internal and external semieliptic crack-like defects detected by technical diagnostics taking into account results of experimental investigations of critical crack resintance. The admissible sizes of the studied defects depending on the depth of drilling are determined.

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