A Study of Acoustic Emission Produced by Strength Test on Bio-Ceramics: The Dependency of Roughness on Mechanical and AE Characteristics

2009 ◽  
Author(s):  
Mitsuyuki Nakayama ◽  
Hideto Suzuki
Keyword(s):  
Surface Roughness ◽  
Acoustic Emission ◽  
Mechanical Characteristics ◽  
Strength Test ◽  
Mechanical Parameters ◽  
Average Roughness ◽  
Living Body ◽  
The Third ◽  
As Stress ◽  
Fine Ceramics

Recently, ceramics has been using widely as living body material. It is called “bioceramics”. Both strength and elasticity of a living body material need almost three times larger than that of elaborate bone. However, it is difficult to satisfy the condition. So bioceramics is inferior to an elaborate bone. The purpose of this research is to obtain a basic data for improving the mechanical characteristics of bioceramics by the Acoustic Emission (AE) method. It was discussed how average roughness depends on mechanical characteristic and AE parameter of bioceramics. The following results were obtained. The first, the bioceramics showed a positive correlation between sound velocity and Kurtosis, that is one of the important parameter for the surface roughness. The second, it was clarified that same relation was obtained between Kurtosis and such mechanical parameters as stress, Young’s modulus and hardness. The third, these results were in accordance with the theory of fracture mechanics for fine ceramics reported independently by Rice and Aoki.

A Study of Acoustic Emission Produced by Strength Test on Bio-Ceramics: Dependency of AE Duration Time and Mean Frequency on the Material Property

2007 ◽  
Author(s):  
Mitsuyuki Nakayama
Keyword(s):  
Acoustic Emission ◽  
Phase Transformation ◽  
Young’S Modulus ◽  
Material Property ◽  
Mechanical Characteristics ◽  
Young's Modulus ◽  
Tetragonal Zirconia ◽  
Strength Test ◽  
Mean Frequency ◽  
Duration Time

Comparing the mechanical characteristics of bio-ceramics with a elaborate bone, there are two important conditions required for biomaterial. First, the strength must be three times larger than that of a elaborate bone. Second, Young’s modulus must be two or three times larger than that. However, still the biomaterial hasn’t developed which satisfies these conditions. The purpose of this research is to improve the strength of bio-ceramics. It was discussed how the duration time and mean frequency of acoustic emission (AE) parameters depend on time. These parameters are calculated with AE wave on breaking test of a bio-ceramics. The following main results were obtained. First, AE generating pattern is changed by the property of the materials. Second, in tetragonal zirconia polycrystals (TZP), the phase transformation has affected AE parameters. Consequently, it was shown that AE parameters had the material dependability.

The Surface-Roughness of Bearing-Surfaces and its Relation to Oil Film Thickness at Breakdown

1949 ◽  
Vol 161 (1) ◽  
pp. 73-79 ◽  
Author(s):  
A. Cameron
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Hydrodynamic Theory ◽  
Quantitative Relation ◽  
Metal Contact ◽  
Initial Contact ◽  
Frictional Drag ◽  
Average Roughness ◽  
Finished Steel ◽  
Oil Film

In this paper the relation of surface roughness of bearing surfaces to allowable film thickness is studied quantitatively with a simple Michell pad apparatus. The pads used were faced with white metal and ran against mild steel collars. The lubricants studied were water, soap solution, paraffin, and light oil. There was little difference in the frictional behaviour of any of the lubricants, except that the aqueous lubricants would not run with very finely finished steel surfaces. The onset of metal to metal contact was detected by an increase in the frictional drag, and also by the change in electrical conductivity between the pad and collar—an extremely sensitive method. The paper shows that there is, at any rate for this system, a quantitative relation between the total surface roughness of the rubbing surfaces and the calculated oil film thickness both at the initial metal to metal contact and seizure. Initial contact occurs when the outlet film thickness, calculated from normal hydrodynamic theory, falls to three times the maximum surface roughness and seizure occurs when it is double the average roughness.

In Situ: A Novel Approach for the Production of Micro Holes

2010 ◽  
Vol 126-128 ◽  
pp. 885-890
Author(s):  
K.P. Somashekhar ◽  
N. Ramachandran ◽  
Jose Mathew
Keyword(s):  
Surface Roughness ◽  
Process Parameters ◽  
Feed Rate ◽  
Machining Parameters ◽  
Average Roughness ◽  
Arithmetic Average ◽  
Quantitative Correlation ◽  
Good Surface ◽  
Novel Approach ◽  
Micro Holes

This work is on the preparation of microelectrodes for μ-EDM operation using μ-WEDG process. Electrodes of Ø500 μm are fabricated with various discharge energy machining conditions. Effects of gap voltage, capacitance & feed rate on the surface finish of the electrodes and overcut of the thus produced micro holes are investigated. The profile of microelectrodes is measured using surface roughness tester with 2μm stylus interfaced with SURFPAK software. The study demonstrated that for brass electrodes an arithmetic average roughness value as low as 1.7μm and an overcut of 3 µm could be achieved. The significant machining parameters are found using ANOVA. Surface of the produced microelectrodes are examined using Scanning Electron Microscope. μ-WEDG process parameters could be adjusted to achieve good surface integrity on microelectrodes. Experimental results showed that the surface roughness of microelectrodes depended primarily on feed rate of the electrode. The observations showed the clear and quantitative correlation existing between the micrometer level surface quality and process parameters. The resulting microelectrodes are found to be of exceptionally high quality and could be used for μ- EDM operation on different types of work materials.

Experiment on Surface Roughness and Acoustic Emission Signal in Infeed Period of Cylindrical Plunge Grinding

2013 ◽  
Vol 690-693 ◽  
pp. 2442-2445 ◽  
Author(s):  
Hao Lin Li ◽  
Hao Yang Cao ◽  
Chen Jiang
Keyword(s):  
Surface Roughness ◽  
Acoustic Emission ◽  
Acoustic Emission Signal ◽  
Feed Rate ◽  
Grinding Process ◽  
Experiment Research ◽  
Plunge Grinding ◽  
Emission Signal ◽  
Ae Signal ◽  
Ae Signals

This work presents an experiment research on Acoustic emission (AE) signal and the surface roughness of cylindrical plunge grinding with the different infeed time. The changed infeed time of grinding process is researched as an important parameter to compare AE signals and surface roughnesses with the different infeed time in the grinding process. The experiment results show the AE signal is increased by the increased feed rate. In the infeed period of the grinding process, the surface roughness is increased at first, and then is decreased.

High Frequency Acoustic Signal Analysis for Internal Surface Pipe Roughness Classification

2011 ◽  
Vol 83 ◽  
pp. 249-254
Author(s):  
Z. M. Hafizi ◽  
Che Ku Eddy Nizwan ◽  
M.F.A. Reza ◽  
M.A.A. Johari
Keyword(s):  
Surface Roughness ◽  
Acoustic Emission ◽  
Control Valve ◽  
Internal Surface ◽  
Corrosion Monitoring ◽  
Emission Analysis ◽  
Pressure Water ◽  
Pipe Roughness ◽  
The Time Domain ◽  
Roughness Classification

This research highlights a method of acoustic emission analysis to distinguish the internal surface roughness of pipe. Internal roughness of pipe indicates the level of corrosion occurring, where normally it is difficult to be monitored online. Acoustic Emission (AE) technique can be used as an alternative solution for corrosion monitoring in pipes, especially for complex pipelines that are difficult to achieve by other monitoring devices. This study used a hydraulic bench to provide fluid flow at two different pressures in pipes with different internal surface roughness (rough and smooth). The main source of acoustic emission was from activity in the control valve, coupled with high pressure water flow friction on the surface of the pipe. The signal from these sources was detected by using the AED-2000V instrument and assisted by the Acoustic Emission Detector (AED) software. The time domain parameter; root mean square, RMS amplitude were processed and compared at different pressures for each type of internal pipe roughness at ten different locations. It was observed that a unitless Bangi number, AB, derived from RMS values, can be used for discriminating different level of internal surface roughness. Internal surface pipe can still be considered as smooth if AB value is above 1.0.

scholarly journals Comparison of Polishing Methods Used in Extrinsic Discolouration of Primary Teeth in Terms of Surface Roughiness 

2021 ◽  
Author(s):  
Burcu Duman ◽  
Salih Doğan
Keyword(s):  
Surface Roughness ◽  
Primary Teeth ◽  
Plaque Formation ◽  
Tooth Surface ◽  
Primary Tooth ◽  
Average Roughness ◽  
Primary Molar ◽  
Biofilm Growth ◽  
Tooth Discoloration ◽  
Significant Difference

Abstract BackgroundSurface roughness is one of the main factors affecting bacterial adhesion, biofilm growth, plaque formation and coloration on the tooth surface. Improper polishing may increase roughness or not contribute to a reduction in roughness while removing biofilms on tooth surfaces. The aim of this study is to examine the effects of different polishing pastes applied to the enamel of primary teeth on the surface roughness through AFM, which enables a more detailed examination of the measurements, and to evaluate the roughness changes created by the paste on the surface. MethodsIn the present study, in order to compare polishing made using Septodent Détartrine, Kerr Cleanic, Shofu Mersaage Regular under the recommendations of the companies in addition to the application of pumice with a rubber brush, a total of 88 samples with 22 samples in each group were created using 88 primary molar teeth. Before and after polishing, roughness measurements and visualizations were performed with atomic force microscopy (AFM). After polishing, Ra (average roughness) values, which express the surface roughness of the re-scanned samples, were calculated so that the samples were the same as the first scanning. For statistical analysis, Shapiro-Wilk normality test and generalized linear models tests were applied and p <0.05 was considered as statistically significantResultsIn the groups; while there was no significant difference in terms of roughness values ​​(Ra) within the group (p> 0.05), a statistically significant reduction in roughness (Ra) was observed on the sample surfaces after polishing in all groups compared to the baseline (p <0.05). According to the data obtained; all polishing methods used in the treatment of primary tooth discoloration can reduce the plaque formation and thus the amount of recoloring by reducing the surface roughness at a similar level.ConclusionAccordingly, it has been observed that the current polishing pastes do not provide a significant advantage over the traditional polishing method (polishing brush with pumice) in terms of surface roughness in removing discoloration in primary teeth.

Effects of a stylus on the surface roughness determination in a contact method for paper and paperboard

2019 ◽  
Vol 34 (4) ◽  
pp. 442-452 ◽  
Author(s):  
Hyun Seok Jeong ◽  
Young Chan Ko ◽  
Hyoung-Jin Kim
Keyword(s):  
Surface Roughness ◽  
Surface Characterization ◽  
Paper Industry ◽  
Surface Friction ◽  
Thickness Measurement ◽  
Mean Deviation ◽  
Contact Method ◽  
Average Roughness ◽  
Practical Applications ◽  
Type Contact

Abstract Surface characterization is important and has many applications in the paper industry. It includes both surface roughness and surface friction. In determining the surface roughness of paper and paperboard, non-contact methods such as air-leak methods In characterizing the surface roughness of paper and paperboard, it has been a common practice that the average roughness with the coefficient of variation (COV) has been conventionally determined. This practice, however, this runs the risk of drawing wrong conclusions since two different surfaces having the same average roughness and COV can exhibit totally different properties. To avoid such mistake, a stylus-type contact method has been developed to determine surface roughness of paper and paperboard such as printing & writing (P&W), kraft and liners. In this method, surface roughness profile has been generated to determine its variability which has been defined as the mean deviation from the roughness average, referred to as MDRA. In determining the MDRA, it is noted that thickness measurement is not required. In this method, stylus shape and size, contact force of the stylus to the surface, scan speed and resolution have been identified as the key parameters of generating stable surface roughness profiles. It has been further identified that the optimal conditions on these parameters should depend on paper grade. It is suggested that a stylus-type contact method should be used to determine surface roughness of paper and paperboard to help determine their practical applications such as printing, coating and embossing.

scholarly journals Experimental Research on the Mechanical Characteristics and the Failure Mechanism of Coal-Rock Composite under Uniaxial Load

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Ke Yang ◽  
Zhen Wei ◽  
Xiaolou Chi ◽  
Yonggang Zhang ◽  
Litong Dou ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Acoustic Emission ◽  
Elastic Modulus ◽  
Crack Propagation ◽  
Failure Mechanism ◽  
Poisson’S Ratio ◽  
Mechanical Characteristics ◽  
Poisson's Ratio ◽  
Energy Value ◽  
Coal Rock

Due to the influence of the component structure and combination modes, the mechanical characteristics and failure modes of the coal-rock composite show different characteristics from the monomer. In order to explore the effect of different coal-rock ratios on the deformation and the failure law of the combined sample, the RMT rock mechanics test system and acoustic emission real-time monitoring system are adopted to carry out uniaxial compression tests on coal, sandstone, and three kinds of combined samples. The evolution rules of the mechanical parameters of the combined samples, such as the uniaxial compressive strength, elastic modulus, and Poisson’s ratio, are obtained. The expansion and failure deformation characteristics of the combined sample are analyzed. Furthermore, the evolution laws of the fractal and acoustic emission signals are combined to reveal the crack propagation and failure mechanism of the combined samples. The results show that the compressive strength and elastic modulus of the combined sample increase with the decrease of the coal-rock ratios, and Poisson’s ratio decreases with the decrease of the coal-rock ratios. The strain softening weakens at the postpeak stage, which shows an apparent brittle failure. The combined sample of coal and sandstone has different degrees of damages under load. The coal is first damaged with a high degree of breakage, with obvious tensile failure. The acoustic emission energy value presents different stage characteristics with increasing load. Crackling sound occurs in the destroy section before the sample reaches the peak, along with small coal block ejection and the partial destruction. The energy value fluctuates violently, with the appearance of several peaks. At the postpeak stage, the coal samples expand rapidly with a loud crackling sound in the destroy section, and the energy value increases dramatically. The crack propagation induces the damage in the sandstone; when the energy reaches the limit value, the instantaneous release of elastic energy leads to the overall structural instability.

Analysis and Prediction of Surface Integrity in Machining: A Review

2014 ◽  
Vol 610 ◽  
pp. 1002-1020 ◽  
Author(s):  
Yuan Gao ◽  
Xin Huang ◽  
Ming Jie Lin ◽  
Zheng Guo Wang ◽  
Rong Lei Sun
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Residual Stresses ◽  
Surface Integrity ◽  
Material Properties ◽  
Cutting Parameters ◽  
Mechanical Parameters ◽  
Factors Affecting ◽  
Grain Size And Shape

Surface integrity is widely used for evaluating the quality of machined components. It has a set of various parameters which can be grouped as: (a) topography parameters such as surface roughness, textures and waviness (b) mechanical parameters such as residual stresses and hardness, and (c) metallurgical state such as microstructure, phase transformation, grain size and shape, inclusions etc. Surface roughness and residual stresses are among the most significant parameters of surface integrity, so that it is worth investigating them particularly. Many factors affect the surface integrity of machined components, including cutting parameters, tool parameters, material properties and vibrations. We can make prediction and optimization for surface integrity by taking advantage of these factors. This paper reviews previous studies and gives a comprehensive summary of surface integrity in the following order: introduction of surface integrity, main parameters of surface integrity, factors affecting surface integrity, prediction and optimization for surface integrity.

Characterization and Laboratory Simulation of Turbine Airfoil Surface Roughness and Associated Heat Transfer

1998 ◽  
Vol 120 (2) ◽  
pp. 337-342 ◽  
Author(s):  
D. G. Bogard ◽  
D. L. Schmidt ◽  
M. Tabbita
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Free Stream ◽  
Laboratory Simulation ◽  
Roughness Effects ◽  
Average Roughness ◽  
Airfoil Surface ◽  
Free Stream Turbulence

The physical characteristics of surface roughness observed on first-stage high-pressure turbine vanes that had been in service for a long period were investigated in this study. Profilometry measurements were utilized to provide details of the surface roughness formed by deposits of foreign materials on different parts of the turbine vane. Typical measures of surface roughness such as centerline average roughness values were shown to be inadequate for characterizing roughness effects. Using a roughness shape parameter originally derived from regular roughness arrays, the turbine airfoil roughness was characterized in terms of equivalent sand-grain roughness in order to develop an appropriate simulation of the surface for laboratory experiments. Two rough surface test plates were designed and fabricated. These test plates were evaluated experimentally to quantify the heat transfer rate for flow conditions similar to that which occurs on the turbine airfoil. Although the roughness levels on the two test plates were different by a factor of two, both surfaces caused similar 50 percent increases in heat transfer rates relative to a smooth surface. The effects of high free-stream turbulence, with turbulence levels from 10 to 17 percent, were also investigated. Combined free-stream turbulence and surface roughness effects were found to be additive, resulting in as much as a 100 percent increase in heat transfer rate.

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