scholarly journals Removal mechanism of machinable ceramics and theoretical model of cutting force in turning operation

2019 ◽  
Vol 10 (2) ◽  
pp. 429-436
Author(s):  
Tao Liu ◽  
Lianjie Ma ◽  
Ye Wang ◽  
Wei Bai ◽  
Hao Chang
Keyword(s):  
Theoretical Model ◽  
Cutting Force ◽  
Cutting Speed ◽  
Propagation Path ◽  
Removal Mechanism ◽  
System A ◽  
Predicted Values ◽  
Experimental Values ◽  
Turning Test ◽  
Good Agreement

Abstract. The removal mechanism of machinable ceramics in turning was studied, and a theoretical model of cutting force based on energy theory was proposed. Based on the turning test of machinable ceramics and kinematics analysis of the tool-workpiece system, a model of tool-workpiece contact zone considering the tool tip arc radius was established. The crack propagation path and three stages of the crack development were analyzed from the stress perspective. Then the energy of the crack system was studied, and the brittle fracture energy which is more suitable for brittle materials was put forward. Based on the principle of energy conservation, a correction theoretical model of cutting force was established, which was verified by turning experiments of machinable ceramics. The results indicated that the predicted values of the model were in good agreement with the experimental values. Both theoretical model and experimental results demonstrated that the cutting force decreased as cutting speed increased, and increased as cutting depth and feed rate increased. This model enabled an in-depth understanding of the interaction action between the cutting tool and work materials involved in the turning of machinable ceramics.

Prediction of the Condensation Coefficient on Horizontal Integral-Fin Tubes

1985 ◽  
Vol 107 (2) ◽  
pp. 369-376 ◽  
Author(s):  
R. L. Webb ◽  
T. M. Rudy ◽  
M. A. Kedzierski
Keyword(s):  
Surface Tension ◽  
Theoretical Model ◽  
Surface Tension Force ◽  
Tension Force ◽  
Condensation Coefficient ◽  
Film Drainage ◽  
Predicted Values ◽  
Experimental Values ◽  
Fin Tubes

A theoretical model is developed for prediction of the condensation coefficient on horizontal integral-fin tubes for both high and low surface tension fluids. The model includes the effects of surface tension on film drainage and on condensate retention between the fins. First, the fraction of the tube circumference that is flooded with condensate is calculated. Typically, the condensation coefficient in the flooded region is negligible compared to that of the unflooded region. Then the condensation coefficient on the unflooded portion is calculated, assuming that surface tension force drains the condensate from the fins. The model is used to predict the R-11 condensation coefficient on horizontal, integral-fin tubes having 748, 1024, and 1378 fpm. The predicted values are within ±20 percent of the experimental values.

Theoretical Model of the Spanwise Mixing Caused by Periodic Incoming Wakes

1994 ◽  
Author(s):  
K. Imanari
Keyword(s):  
Experimental Data ◽  
Theoretical Model ◽  
Turbulent Diffusion ◽  
Axial Flow ◽  
Single Stage ◽  
Mixing Coefficients ◽  
Predicted Values ◽  
Good Agreement ◽  
Axial Flow Compressors

A theoretical model is proposed for the spanwise mixing caused by periodic incoming wakes in the context of turbulent diffusion in axial-flow compressors prior to repeating-stage conditions. The model was used to predict the spanwise mixing coefficients across a stator of a single-stage compressor without IGVs. The correctness of the theory was demonstrated by the results that the predicted values were in good agreement with the associated experimental data.

Influence of Particle Size on Machinability Behavior in Turning of AA6061-AlN Composites

2019 ◽  
Vol 6 (1) ◽  
pp. 53-74
Author(s):  
Arumugam Mahamani
Keyword(s):  
Surface Roughness ◽  
Cutting Force ◽  
Flank Wear ◽  
Cutting Speed ◽  
Dimensional Accuracy ◽  
Reinforced Composite ◽  
Current Article ◽  
Machining Rate ◽  
Particle Reinforced Composite ◽  
Turning Test

Machinability of the composites and achieving the dimensional accuracy in addition to surface finish at an economic machining rate is still the topic for numerous researchers. The current article describes the variation in machinability characteristics of AA6061-AlN composites under various sizes of reinforcements. Cutting speed, cutting depth and feed rate are preferred to perform the turning test. Cutting force, surface roughness and flank wear are identified to appraise the machinability characteristics. For an identical machining condition, the nano particle reinforced composite has less surface roughness and minimal flank wear and a greater cutting force than the other composites. An increment in cutting speed raises the flank wear and declines the surface roughness and cutting force for all composites. The findings from the experimental investigation help to utilize the turning process for machining the composites with various sizes of reinforcement at the economic rate of machining without compromising the surface quality.

Influence of the Contact Pressure on the Rolling Resistance Moments in Dry Ball-Race Contacts

2014 ◽  
Vol 658 ◽  
pp. 305-310
Author(s):  
Alina Corina Dumitrascu ◽  
Gelu Ianus ◽  
Dumitru Olaru
Keyword(s):  
Theoretical Model ◽  
Contact Pressure ◽  
Rotational Speed ◽  
Ball Bearing ◽  
Rolling Resistance ◽  
Theoretical Models ◽  
Hertzian Contact ◽  
Experimental Methodology ◽  
Experimental Values ◽  
Good Agreement

Based on a theoretical model and an experimental methodology for defining the rolling resistance moments in a modified thrust ball bearing having only 3 balls, the authors experimentally investigated the influence of the Hertzian contact pressure on rolling resistance moments between a ball and a race. The experiments were realized with balls having diameters between 1.588 mm and 4.762 mm with maximum Hertzian pressure between 0.2GPa and 1GPa, operating for rotational speed between 60rpm to 210 rpm. The experiments evidenced that the measured values of the rolling resistance moments have higher values that the theoretical hysteresis and curvature rolling resistance moments for low contact pressure. By increasing of the contact pressure to 1GPa the experimental values for rolling resistance moments are in good agreement with the theoretical models.

scholarly journals Effects of Parameters on Solvent Extraction of Oil From Sandbox (Hura Crepitans) Seed Oil Using 2^4 Factorial Design

2021 ◽  
Vol 15 ◽  
pp. 48-55
Author(s):  
Owhor Sampson Chisa ◽  
J. D. Amine ◽  
Abdul Gambo Alim ◽  
Luka Bobby Shakarau ◽  
Isaiah Kehinde Ogbobame ◽  
...  
Keyword(s):  
Solvent Extraction ◽  
Seed Oil ◽  
Hydraulic Press ◽  
Biodiesel Production ◽  
Extraction Temperature ◽  
Physiochemical Properties ◽  
Hura Crepitans ◽  
Predicted Values ◽  
Experimental Values ◽  
Good Agreement

The present work deals with the production of biodiesel from Sandbox (Hura crepitans) seed oil and the optimization of the parameters that influence the transesterification of Sandbox (Hura crepitans)seed oil into biodiesel using Response Surface Methodology. Hura crepitans oil was obtained from by using hydraulic press for Mechanical and n-hexane for solvent extraction. Esterification was done using methanol and sodium hydroxide. A total of 48 experiments using Central Composite Design were carried out. The R-Squared, Adequate Precision, Predicted and Adjusted R-Squared values were 0.9367, 19.219, 0.8576 and 0.9070 respectively. The result of the extraction of oil, physiochemical properties, and optimization process shows that sandbox (Hura crepitans) seed oil has characteristics that are more favorable to biodiesel production. The optimal conditions for extraction of oil from sandbox seed oil were given as alcohol/ oil ratio of 5.0, catalyst amount of 20 g/ml, extraction temperature of 60 ºC, and extraction time of 45.01 minutes, with the predicted oil yield as 97.33% respectively which shows that the experimental values are in good agreement with predicted values.

scholarly journals Estimation of Activity Interaction Parameters in Fe-S-j Systems

Entropy ◽  
2018 ◽  
Vol 20 (10) ◽  
pp. 808 ◽  
Author(s):  
Tianhua Ju ◽  
Xueyong Ding ◽  
Yingyi Zhang ◽  
Weiliang Chen ◽  
Xiangkui Cheng ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Excess Entropy ◽  
Geometric Model ◽  
Calculation Model ◽  
Interaction Parameters ◽  
Mixing Enthalpy ◽  
Predicted Values ◽  
Experimental Values ◽  
Activity Interaction Parameter ◽  
Good Agreement

It is important to know the activity interaction parameters between components in melts in the process of metallurgy. However, it’s considerably difficult to measure them experimentally, relying still to a large extent on theoretical calculations. In this paper, the first-order activity interaction parameter (esj) of j on sulphur in Fe-based melts at 1873 K is investigated by a calculation model established by combining the Miedema model and Toop-Hillert geometric model as well as considering excess entropy and mixing enthalpy. We consider two strategies, with or without using excess entropy in the calculations. Our results show that: (1) the predicted values are in good agreement with those recommended by Japan Society for Promotion of Science (JSPS); and (2) the agreement is even better when excess entropy is considered in the calculations. In addition, the deviations of our theoretical results from experimental values eS(exp)j-eS(cal)j depend on the element j’s locations in the periodic table.

An Analytical Examination of the Combustion of a Turbulent Jet in an Environment of Air Containing a Premixed Fuel or a Diluent

1995 ◽  
Vol 117 (3) ◽  
pp. 234-238 ◽  
Author(s):  
P. Wierzba ◽  
G. A. Karim ◽  
I. Wierzba
Keyword(s):  
Flame Length ◽  
Turbulent Jet ◽  
Simple Analytical Model ◽  
Flammability Limits ◽  
Gaseous Fuels ◽  
Gaseous Environment ◽  
Fuel Jet ◽  
Predicted Values ◽  
Experimental Values ◽  
Good Agreement

A simple analytical model for the mixing and combustion of an axisymmetric turbulent gaseous fuel jet discharging into a co-flowing streaming gaseous environment of an auxiliary fuel and/or a diluent homogeneously mixed with air is presented. A number of gaseous fuels and diluents are considered. It is shown that the combustion characteristics of a fuel jet can be modified significantly by the presence of a relatively small amount of a fuel in the surrounding air at concentrations well below the corresponding local flammability limits. Correlative procedures are presented for estimating changes in the flame length, the size of the combustion zone, and the blowout limits with changes in the type and concentration of the fuel in the surroundings. Predicted values showed generally good agreement with the corresponding experimental values.

Modeling and investigation of cutting force for SiCp/Al composites during ultrasonic vibration-assisted turning

2021 ◽  
pp. 095440892110607
Author(s):  
Jieqiong Lin ◽  
Chao Wang ◽  
Mingming Lu ◽  
Jiakang Zhou ◽  
Shixin Zhao ◽  
...  
Keyword(s):  
Prediction Model ◽  
Cutting Force ◽  
Ultrasonic Vibration ◽  
Cutting Speed ◽  
Machining Process ◽  
Depth Of Cut ◽  
Cutting Force Prediction ◽  
Force Prediction ◽  
Depth Direction ◽  
Experimental Values

The machining process of SiCp/Al composites is considerably difficult because of the addition of ceramic particles. As an effective machining method, ultrasonic vibration-assisted turning is used to process SiCp/Al composites, which can effectively reduce the cutting force, improve the surface quality, and reduce the tool wear. This study developed a cutting force prediction model for ultrasonic vibration-assisted turning of SiCp/Al composites, which comprehensively considers the instantaneous depth of cut and the instantaneous shear angle. This model divides the cutting force into the chip formation force considering the instantaneous depth of cut, the friction force considering the influence of SiC particles at tool-chip interface, the particle fracture force, and the ultrasonic impact force in the cutting depth direction. By comparing the predicted value of the main cutting force with the experimental values, the results present the same trend, which verifies the feasibility of the cutting force prediction model. In addition, the influence of vibration amplitude, depth of cut, and cutting speed on the main cutting force is analyzed. The systematic cutting experiments show that ultrasonic vibration-assisted turning can significantly reduce the cutting force and improve the machinability of SiCp/Al composites.

A Thermodynamic Analysis of the Rich Flammability Limits of Fuel-Diluent Mixtures in Air

1995 ◽  
Vol 117 (3) ◽  
pp. 239-242 ◽  
Author(s):  
S. O. Bade Shrestha ◽  
I. Wierzba ◽  
G. A. Karim
Keyword(s):  
Atmospheric Temperature ◽  
Flammability Limit ◽  
Flammability Limits ◽  
Wide Range ◽  
Temperature And Pressure ◽  
The Rich ◽  
Predicted Values ◽  
Experimental Values ◽  
Good Agreement ◽  
Propane Butane

A simple approach is described for the calculation of the rich flammability limits of fuel-diluent mixtures in air for a wide range of initial temperatures based only on the knowledge of the flammability limit of the pure fuel in air at atmospheric temperature and pressure conditions. Various fuel-diluent mixtures that include the fuels methane, ethylene, ethane, propane, butane, carbon monoxide, and hydrogen, and the diluents nitrogen, carbon dioxide, helium, and argon have been considered. Good agreement is shown to exist between predicted values of the rich flammability limits and the corresponding available experimental values for the fuel-diluent mixtures.

scholarly journals Modeling of Hydrodynamics in a 25 mm ϕ Pulsed Disk and Doughnut Column

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Rajnish Kumar ◽  
D. Sivakumar ◽  
Shekhar Kumar ◽  
U. Kamachi Mudali
Keyword(s):  
Slip Velocity ◽  
Drop Size ◽  
Absolute Error ◽  
Model Parameters ◽  
Dispersed Phase ◽  
Acid System ◽  
Hydrodynamic Parameters ◽  
Predicted Values ◽  
Experimental Values ◽  
Good Agreement

The hydrodynamic parameters, namely, dispersed phase holdup and flooding throughput, have been investigated in 25 mm diameter pulsed disk and doughnut column (PDDC), in no mass transfer conditions. In this work, using existing correlations on plate pulsed columns, the dispersed phase holdup and the flooding throughput are empirically modelled well using the slip velocity concept. A good agreement is observed between experimental values and predicted values obtained from empirical correlation. The experimental data for dispersed phase holdup and flooding throughput has been modelled using the Van Delden model to describe the hydrodynamics characteristics of a PDDC and necessary adjustable parameters for drop size distribution and dispersed phase holdup are updated for 30% TBP-nitric acid system. The model parameters were estimated by minimizing the absolute error between experimental and theoretical values of flooding throughput and holdup data. It was found that the measured values and observed trends could be described accurately using this model after fitting holdup and flooding data. The error between the experimental and theoretical values of flooding throughput and holdup was found to be less than 10%.

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