Study on NC Compliant Bonnet Tool Abrasive Polishing Based on Magnetorheological Torque Servo

2010 ◽  
Vol 443 ◽  
pp. 411-416 ◽  
Author(s):  
Yong Jie Shi ◽  
Di Zheng ◽  
Jian Ming Zhan ◽  
Long Shan Wang ◽  
Xiao Feng Liu ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Contact Pressure ◽  
Applied Load ◽  
Initial Pressure ◽  
Radius Of Curvature ◽  
Hertz Theory ◽  
Factors Affecting ◽  
Polishing Force ◽  
Polishing Tool ◽  
Polishing Efficiency

In this paper, a NC compliant abrasive polishing system was developed based on a magnetorheological torque servo (MRT), using a bonnet as the polishing tool. The MRT was uesd to provide a load acting on bonnet tool to produce the polishing force. In order to find the factors affecting the polishing quality, the models of the applied load, polishing force and contact pressure between the bonnet and the part were established based on Hertz theory, and the factors affecting the contact pressure were analyzed. Theoretical analysis indicated that there was a significant effect of the applied load, the initial pressure of the bonnet and the radius of curvature of the part on contact pressure. Experiments were carried out to verify the validity of the models, and experiment results showed that the roughness of the part was improved greatly and the polishing efficiency could be controlled by changing the initial pressure of the bonnet and applied load.

Effects of Curvature on Material Removal in NC Polishing of Aspheric Part

2012 ◽  
Vol 428 ◽  
pp. 28-32
Author(s):  
Di Zheng ◽  
Yong Jie Shi ◽  
Yuan Wang ◽  
Xiao Jun Zhao ◽  
Lun Pan ◽  
...  
Keyword(s):  
Material Removal Rate ◽  
Material Removal ◽  
Removal Rate ◽  
Radius Of Curvature ◽  
Removal Rates ◽  
Hertz Theory ◽  
Polishing Force ◽  
Polishing Pressure

The objective of this paper is to investigate the effect of radius of curvature on the material removal in the NC polishing of aspheric part. The models of polishing pressure and material removal rates were established based on Preston equation and Hertz theory. The material removal rates was analyzed. Experiments were carried out. Results showed that the material removal rate varies with the variations of the curvature under a constant polishing force and velocity, and the part can not be polished uniformly.

Modeling and Analysis of NC Compliant Abrade Polishing for Surface of Revolution

2010 ◽  
Vol 97-101 ◽  
pp. 4057-4060
Author(s):  
Yong Jie Shi ◽  
Di Zheng ◽  
Jian Ming Zhan ◽  
Long Shan Wang
Keyword(s):  
Contact Pressure ◽  
Hertz Theory ◽  
Modeling And Analysis ◽  
Head Posture ◽  
Surface Of Revolution ◽  
Polishing Force ◽  
The Impact

In this paper, a compliant tool was designed for abrade polishing parts with surface of revolution on general NC lathe. The tool can adapt itself automatically to the part’s surface. A magnetorheological torque servo driver (MRT) was developed to control independently the polishing force between the tool and the surface which determines the contact pressure and affects the polishing quality. The models of polishing force and contact pressure were established based on Hertz theory. The model of tool head posture was deduced. The impact of tool head posture and position on contact pressure was analyzed. The experiment results verified the validity of the compliant tool and models.

Factors Affecting the Learning of Foreign Language Vocabulary: Imagery Keyword Mediators and Phonological Short-Term Memory

1993 ◽  
Vol 46 (3) ◽  
pp. 533-558 ◽  
Author(s):  
Nick Ellis ◽  
Alan Beaton
Keyword(s):  
Theoretical Analysis ◽  
Foreign Language ◽  
Cognitive Processes ◽  
Short Term Memory ◽  
Vocabulary Learning ◽  
Short Term ◽  
Term Memory ◽  
Factors Affecting ◽  
Foreign Word ◽  
Lexical Factors

In order to investigate the cognitive processes involved in learning Foreign Language (FL) vocabulary, this study evaluates different methods of instruction. It demonstrates that keyword techniques are effective for receptive learning but that repetition is a superior strategy for learning to produce the foreign word. Performance is optimal when learners combine both strategies. The nature of the keyword is crucial–-whereas imageable noun keywords promote learning, verb keywords actually impede it. A theoretical analysis of the roles of phonological short-term memory, imagery, and lexical factors in FL vocabulary learning is presented.

scholarly journals Optimization of the Polishing Efficiency and Torque by Using Taguchi Method and ANOVA in Robotic Polishing

2020 ◽  
Vol 10 (3) ◽  
pp. 824
Author(s):  
Imran Mohsin ◽  
Kai He ◽  
Zheng Li ◽  
Feifei Zhang ◽  
Ruxu Du
Keyword(s):  
Surface Roughness ◽  
Taguchi Method ◽  
Signal To Noise Ratio ◽  
Surface Friction ◽  
Surface Finishing ◽  
Polished Surface ◽  
Machining Parameters ◽  
Regression Equations ◽  
Polishing Force ◽  
Polishing Efficiency

Surface finishing and polishing are important quality assurance processes in many manufacturing industries. A polished surface (low surface roughness) is linked with many useful properties other than providing an appealing gloss to the product, such as surface friction, electrical and chemical resistance, thermal conductivity, reflection, and product life. All these properties require an efficient polishing system working with the best machining parameters. This study analyzed the effects of the different input polishing parameters on the polishing efficiency and torque in the robotic polishing system for the circular-shaped workpieces (such as ring, cylinder, sphere, cone, etc.) by using the Taguchi method and analysis of variance (ANOVA). A customized rotatory passive gripper is designed to hold the watch bezel during polishing. Under the design of experiments (DOE) technique, Taguchi’s L 18 array is selected to find the optimized process parameters for polishing efficiency (based on surface roughness) and torque. Experimental results with the statistical analysis by signal-to-noise ratio and ANOVA (95% confidence level) confirms that the polishing force and tool speed are the most influencing parameter for polishing efficiency in the system. Linear regression equations are modeled for the polishing efficiency and torque. Finally, a confirmation test is conducted for the validation of the experimentation results against actual results.

On the Nature of O-Rings in Contact With Rough Surfaces

1988 ◽  
Vol 110 (4) ◽  
pp. 632-637 ◽  
Author(s):  
W. E. Warren ◽  
J. G. Curro ◽  
D. E. Amos
Keyword(s):  
Theoretical Analysis ◽  
Root Mean Square ◽  
Contact Pressure ◽  
Contact Force ◽  
Rough Surfaces ◽  
Fundamental Importance ◽  
Elastic Behavior ◽  
Surface Irregularity ◽  
Mean Square ◽  
Irregular Surfaces

This work provides a theoretical analysis of the elastic behavior of an O-ring compressed between two rigid plates with irregular surfaces. Relations between deflection, contact force and contact pressure are obtained. The contact pressure, which is of fundamental importance in establishing criteria for effective sealing, is dependent upon both the amplitude and wavelength of the surface irregularity. This analysis suggests that surfaces in contact with O-ring seals should be characterized by the root mean square slope Δq in addition to the usual Ra which depends on amplitude only.

An investigation into contact pressure distribution in bolted joints

2014 ◽  
Vol 228 (18) ◽  
pp. 3405-3418 ◽  
Author(s):  
JT Stephen ◽  
MB Marshall ◽  
R Lewis
Keyword(s):  
Pressure Distribution ◽  
Contact Pressure ◽  
Applied Load ◽  
Plate Thickness ◽  
Operating Conditions ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Contact Pressure Distribution ◽  
Engineering Structures ◽  
Peak Value

Bolted joints are widely used in modern engineering structures and machine designs due to their low cost and reliability when correctly selected. Their integrity depends on quantitative representation of the contact pressure distribution at the interface during design. Because of the difficulty in reaching and assessing clamped interfaces with traditional experimental methods, presently bolted joint design and evaluation is based on theoretical analysis, with assumptions to quantify pressure distribution at the clamped interface, which may not represent their true operating conditions. The present work utilises a non-intrusive ultrasonic technique to investigate and quantify the pressure distribution in bolted joints. The effect of variation in plate thickness on the contact pressure distribution at bolted interfaces under varying axial loads is investigated. While it was observed that the contact pressure at the interface increases as the applied load increases, the distance from the edge of the bolt hole at which the distribution becomes stable is independent of the applied load on the bolted joint. However, the contact pressure distribution was observed to vary with the plate thickness. Although the variation in the peak value of the average contact pressure distribution in bolted joints does not depend on the plate thickness, the distance from the edge of bolt hole at which the value of the distribution becomes stable increases as the plate thickness is increased. It was also observed that the edge of the bolt head affected the position of the peak value of the contact pressure distribution at the interface, though its effect was dependent on plate thickness. Furthermore, a model based on a Weibull distribution has been proposed to fit the experimental data and a good correlation was observed.

Optimization of Radial Cams with Translating Roller Follower through Genetic Algorithms

2015 ◽  
Vol 783 ◽  
pp. 83-94
Author(s):  
Alberto Borboni
Keyword(s):  
Genetic Algorithm ◽  
Genetic Algorithms ◽  
Contact Pressure ◽  
Optimization Problem ◽  
Optimization Method ◽  
Optimization Process ◽  
Radius Of Curvature ◽  
Design Problems ◽  
Computational Optimization ◽  
Different Types

In this work, the optimization problem is studied for a planar cam which rotates around its axis and moves a centered translating roller follower. The proposed optimization method is a genetic algorithm. The paper deals with different design problems: the minimization of the pressure angle, the maximization of the radius of curvature and the minimization of the contact pressure. Different types of motion laws are tested to found the most suitable for the computational optimization process.

Stress Analysis in the Combination of Footplate and Caisson Foundation

2016 ◽  
Vol 845 ◽  
pp. 89-93
Author(s):  
Niken Silmi Surjandari ◽  
Yusep Muslih Purwana ◽  
Rensia Erlyana Majid
Keyword(s):  
Bearing Capacity ◽  
Stress Analysis ◽  
Plane Strain ◽  
Contact Pressure ◽  
Applied Load ◽  
Low Cost ◽  
Strain Condition ◽  
Conservative Approach ◽  
Depth Variation ◽  
Properties Of Soil

Currently, the combined footplate-caisson foundation has been used for some projects. This type of foundation is one of the chosen low cost foundations for the structure supporting medium load when the bearing capacity of conventional foundation is not sufficient. The inserted caisson underneath the footing enables to increase its performance; has a better bearing capacity and lower settlement. Unfortunately, the theoretical basic regarding this foundation is not available so that the design tends to use a conservative approach. For this reason, the study on footplate-caisson foundation is essential to obtain the information of its performances. In this study, the combined footplate-caisson was numerically modelled in plane-strain condition as a foundation resting on clay. The footplate was modelled in the depth variation of 0.75 m up to 1.5 m in fixed width of 1.5 m x 1.5 m; whereas the caisson was modelled in depth variation of 0.75 up to 4.5 m in fixed diameter of 1.0 m. The properties of soil and foundation are presented in the paper. The applied load on the model was varied from 60 kPa up to 1000 kPa. The result of the study indicates that the presence of caisson contributes to the decrease in contact pressure in footplate. The percentage of the contribution depends on the dimension of each element and the depth of caisson.

Plastic Yield Conditions for Adhesive Contacts

2008 ◽  
Author(s):  
Yu-Chiao Wu ◽  
George G. Adams
Keyword(s):  
Applied Load ◽  
Contact Theory ◽  
Hertz Contact ◽  
Hertz Theory ◽  
Yield Load ◽  
Plastic Yield ◽  
Curve Fit ◽  
Axis Of Symmetry ◽  
Adhesive Contacts ◽  
Yield Conditions

The Hertz contact theory allows the onset of yielding to be predicted for those contacts in which the effect of adhesion can be neglected. However in microscale contacts, such as those which occur in MEMS, yielding will occur for lower loads than predicted by the Hertz theory. For such cases, the JKR, DMT, and Greenwood-Johnson theories extend the Hertz theory to include the effect of adhesion. The present study provides yield conditions for the JKR, DMT, and Greenwood-Johnson theories of adhesion. Attention is first focused on the initiation of yield along the axis of symmetry of the contact. The results show that the critical loads for the three adhesion theories are close together, but differ significantly from that predicted by Hertz. In fact it is possible for yielding to occur due to adhesion alone, without an external applied load. A curve-fit formula is given to express the yield load as a function of an adhesion parameter for different Poisson’s ratios. Results are also obtained for the onset of plastic deformation away from the axis of symmetry using the Greenwood-Johnson theory of adhesion.

Stress intensity factors and fatigue life of beams in reversed bending

1997 ◽  
Vol 32 (6) ◽  
pp. 401-409 ◽  
Author(s):  
R Moobola ◽  
D A Hills ◽  
D Nowell
Keyword(s):  
Fatigue Life ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Applied Load ◽  
Intensity Factors ◽  
Transverse Cracks ◽  
Factors Affecting ◽  
Distribution Of Dislocations ◽  
Representative Material

Two problems concerning the propagation of transverse cracks through beams are studied with a crack modelled as a distribution of dislocations. The first consists of a surface breaking normal crack present in reversing bending, where it is shown that for deep cracks two cycles of loading are experienced for each cycle of applied load. The second is an initially buried normal crack, where stress intensity factors affecting propagation both towards the surface and into the beam are evaluated. The effect on the life of each of these components is then considered for a representative material.

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