Drill Bit Design Features that Initiate and Reduce High Frequency Torsional Oscillations

2021 ◽  
Author(s):  
Reed W. Spencer ◽  
John A. Bomidi ◽  
Xu Huang
Keyword(s):  
High Frequency ◽  
Torsional Oscillation ◽  
Low Frequency ◽  
Depth Of Cut ◽  
Drill Bit ◽  
Drilling Rig ◽  
Rock Types ◽  
Frequency Changes ◽  
Tangential Acceleration ◽  
Torque Values

Abstract This paper reports the development of and the results of high frequency torsional oscillation (HFTO) tests performed on full-sized PDC drill bits and single cutters in a drilling laboratory. The research team used a pressurized laboratory drilling rig to test different drill bit designs in new and worn conditions. These tests were performed in different rock types, at different revolution per minute (RPM), weight on bit (WOB) and depth of cut (DOC) values. High frequency drill stem torque (5120 Hz) and in-bit tangential acceleration (1400 Hz) data were recorded, along with all other drilling parameters. Spectrograms of torque data were plotted to identify frequency changes in time. The torque data was filtered to remove the low frequency behavior and focus on the HFTO behavior. The high frequency torque signal correlates well with in-bit tangential accelerations. Root mean square (RMS) values of this filtered torque signal were calculated and plotted vs average WOB, depth of cut, and torque values. Sharp and worn bit geometry, were dull graded on a per cutter basis and were input to a 3D drilling modeling software and correlated with test data in order to determine the DOC at which wear flats or cutting faces engage the rock and cause changes in HFTO behavior. The main results from this research are 1) a lab test and data analysis were developed that can measure a drill bit's propensity to initiate HFTO vibrations in the BHA, 2) HFTO RMS high-pass filtered torque values generally increase with DOC, 3) bits in the new state show more HFTO behavior if cutter design is more aggressive, and 4) wear flat engagement causes high HFTO behavior.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

scholarly journals Small-Scale Drilling Test Rig For Investigation of Axial Excitation On The Drilling Process

2018 ◽  
Vol 148 ◽  
pp. 16001
Author(s):  
A. Austefjord ◽  
S. Blaylock ◽  
I. Forster ◽  
M. Sheehan ◽  
C. Wright
Keyword(s):  
High Frequency ◽  
High Speed ◽  
Low Frequency ◽  
Advanced Technology ◽  
Small Scale ◽  
Drilling Process ◽  
Generation Process ◽  
Rock System ◽  
Drilling Rig ◽  
Axial Excitation

This paper describes the design, construction and operation of a small-scale drilling rig for the purpose of investigation of the effect of axial excitation on the drilling process. The rig is bench top in size and has been designed to drill small rock samples, whilst at the same allowing axial excitation to be induced into the drilling process. The rig has been designed to drill the rock without any drilling fluids – so allowing improved observation of the chip generation process. Additionally, the drilling weight on bit is applied via masses, so allowing greater representation of the dynamic behavior of the drilling process – i.e. capturing more natural frequencies. The results from the rig have been obtained over two frequency ranges – low frequency (0-50 Hz) and high frequency (50-250 Hz). Results show that improved rate of penetration is obtained with axial excitation – with low and high frequency optima occurring. These optima can be related to the behavior of the string in the two frequency ranges – in the low frequency range, the entire string acts in unison; whereas at high frequency, only the bit/rock system is active. As a result, it is concluded that for low frequency operation, only information about the drill string is required to optimize performance; whereas for high frequency operation, information about the bit/rock system is required to optimize performance. Observation of the chip generation process via high speed video has shown that during axial excitation, regular shaped bricks are ejected when compared with the typical wedge- shaped chips that are normally ejected during the drilling process. It is concluded that, during the axial excitation process, the chips are being ejected via a levering action, so allowing a more efficient and quicker process. MIT [1] provided background classes, project guidance and project review as part of an NOV/MIT advanced technology program. Larger scale lab tests and/or field tests are required to verify/validate these conclusions.

scholarly journals Wave Propagation in Rocks – Investigating the Effect of Rheology

2020 ◽  
Author(s):  
Tamás Fülöp
Keyword(s):  
Wave Propagation ◽  
High Frequency ◽  
Space Dimension ◽  
Low Frequency ◽  
Elastic Behaviour ◽  
Frequency Limit ◽  
Dispersion Error ◽  
Rock Types ◽  
Velocity Prediction ◽  
Symplectic Schemes

Rocks exhibit beyond-Hookean, delayed and damped elastic, behaviour (creep, relaxation etc.). In many cases, the Poynting–Thomson–Zener (PTZ) rheological model proves to describe these phenomena successfully. A forecast of the PTZ model is that the dynamic elasticity coefficients are larger than the static (slow-limit) counterparts. This prediction has recently been confirmed on a large variety of rock types. Correspondingly, according to the model, the speed of wave propagation depends on frequency, the high-frequency limit being larger than the low-frequency limit. This frequency dependence can have a considerable influence on the evaluation of various wave-based measurement methods of rock mechanics. As experience shows, commercial finite element softwares are not able to properly describe wave propagation, even for the Hooke model and simple specimen geometries, the seminal numerical artefacts being instability, dissipation error and dispersion error, respectively. This has motivated research on developing reliable numerical methods, which amalgamate beneficial properties of symplectic schemes, their thermodynamically consistent generalization (including contact geometry), and spacetime aspects. The present work reports on new results obtained by such a numerical scheme, on wave propagation according to the PTZ model, in one space dimension. The simulation outcomes coincide nicely with the theoretically obtained phase velocity prediction.

Environmental Variability and Settlement Changes on the Pajarito Plateau, New Mexico

1991 ◽  
Vol 56 (2) ◽  
pp. 315-332 ◽  
Author(s):  
Janet D. Orcutt
Keyword(s):  
New Mexico ◽  
High Frequency ◽  
Environmental Variability ◽  
Low Frequency ◽  
Pajarito Plateau ◽  
Poor Understanding ◽  
Frequency Changes ◽  
Using Data ◽  
Settlement Changes ◽  
Northern Rio Grande

Recent studies have shown a relation between low- and high-frequency environmental variability and aspects of culture. This paper uses low-frequency alluvial and hydrological changes on the Colorado Plateaus and high-frequency changes in moisture availability for the northern Rio Grande between A.D. 1150 and A.D. 1600 to derive expectations for changes in settlement organization on the Pajarito Plateau. The expectations are evaluated using data on the distribution of population and field houses in elevation zones. Changes in population size and aggregation also are reviewed. Low-frequency processes especially appear to have played a role in settlement change until A.D. 1450. After this date, settlement does not conform to expectations. Reasons for this are suggested, including a poor understanding of low- frequency processes, conflict, and human-induced environmental degradation.

Some chemical and physical aspects of muscle contraction and relaxation

1950 ◽  
Vol 137 (886) ◽  
pp. 63-70 ◽  
Keyword(s):  
Action Potential ◽  
Muscle Contraction ◽  
Muscle Cell ◽  
High Frequency ◽  
Low Frequency ◽  
High Frequency Current ◽  
Fast Decrease ◽  
Frequency Changes ◽  
Contraction And Relaxation ◽  
Frequency Current

We have been interested in three questions in relation to the problem which is under discussion to-day: the impedance changes, the pH changes and the protein changes during muscle contraction and relaxation. (a) Impedance changes With high-frequency current, we were not able to find any change in the conductivity of the muscle cell (Dubuisson 1935, 1936, 1937 a ). This confirms the earlier discoveries of MacClendon (1929) and Hartree (1933). At low frequency, changes were found due to modifications of some interfaces in the muscle cell. There is first of all a very fast decrease of impedance ( a wave) which occurs before the contraction and which is synchronous with the action potential (figure 8). Some years later, K. S. Cole (1938) found the same phenomenon in nerve.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

Efeitos do Método Pilates sobre a variabilidade da frequência cardíaca, flexibilidade e variáveis antropométricas em indivíduos sedentários

2016 ◽  
Vol 17 (1) ◽  
pp. 66
Author(s):  
Maria Lina Silva Leite
Keyword(s):  
High Frequency ◽  
Low Frequency

O objetivo deste estudo foi avaliar os efeitos do Método Pilates sobre a variabilidade da frequência cardíaca, na flexibilidade e nas variáveis antropométricas em indivíduos sedentários. O presente estudo contou com 14 voluntárias do sexo feminino, na faixa etária entre 40 e 55 anos, que realizaram 20 sessões de exercícios do Método Pilates, duas vezes por semana, com duração de 45 minutos cada sessão, dividida em três fases: repouso, exercício e recuperação. As variáveis estudadas foram: os dados antropométricos, flexibilidade avaliada utilizando o teste de sentar-e-alcançar com o Banco de Wells, e intervalos R-R usando um cardiotacômetro. O processamento dos sinais da frequência cardíaca foi efetuado em ambiente MatLab 6.1®, utilizando a TWC. Os dados coletados foram submetidos ao teste de normalidade de Shapiro Wilk e foi utilizado o teste de Wilcoxon e Anova One Way (α = 0,05). Nos resultados, observou-se que não houve diferenças significativas entre os valores antropométricos e de frequência cardíaca, porém houve aumento da flexibilidade com o treinamento. Comparando a primeira e a vigésima sessão com relação aos parâmetros low frequency (LF), high frequency (HF), e relação LF/HF, não houve diferença na fase de repouso e foram constatadas diferenças significativas de LF (p = 0,04) e HF (p = 0,04) na fase de exercício e diferença significativa de LF/HF (p = 0,05) na fase de recuperação. Comparando os parâmetros nos períodos de repouso, exercícios e recuperação durante a primeira sessão e durante a vigésima sessão, não houve diferença significativa nos parâmetros LF, HF e LF/HF. Pode-se concluir que, em relação à flexibilidade, foi observada uma melhora significativa, enquanto a análise da frequência cardíaca caracterizou a intensidade do exercício de 50% da capacidade funcional das voluntárias. Em relação aos parâmetros LF, HF e LF/HF foram observados um aumento da variabilidade da frequência cardíaca, provavelmente produto da atividade do Método Pilates. A Transformada Wavelet (TWC) mostrou-se um Método adequado para as análises da variabilidade da frequência cardíaca.Palavras-chave: frequência cardíaca, Transformada Wavelet, Pilates.

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