scholarly journals Calculation of Friction Force for Slurry Pipe Jacking considering Soil-Slurry-Pipe Interaction

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Yichao Ye ◽  
Limin Peng ◽  
Weichao Yang ◽  
Yang Zou ◽  
Chengyong Cao
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Normal Force ◽  
Analytical Formula ◽  
Design Parameters ◽  
Soil Slurry ◽  
New Approach ◽  
Friction Resistance ◽  
Pipe Jacking ◽  
Effective Friction

This paper aims to provide a new approach to predict the friction resistance of slurry pipe jacking. Friction force usually constitutes the main component of jacking force. It can be calculated by multiplying an effective friction coefficient and the normal force acting on the external surface of the pipe. This effective friction coefficient is introduced to reflect the effect of contact state of pipe soil slurry, highly affected by the effect of lubrication and the interaction of pipe soil slurry. Firstly, by making some reasonable assumptions, the analytical formula of the effective friction coefficient is obtained, in which the critical quantity of contact (contact angle or width) is calculated by using the Persson contact model. Then, the analytical formula of normal force of circular pipeline is derived, which needs to determine the vertical soil pressure. To allow for a better prediction, three typical silo models are introduced and compared. Finally, a method for calculating the friction resistance of slurry pipe jacking is established. The main difference from the existing method is that this method takes into full consideration the influence of lubrication, soil properties (such as internal friction angle, cohesion, and void ratio), and design parameters (such as buried depth, overcut, and pipe diameter). By using reasonable silo models, the predicted results are in good agreement with the measured values collected from 10 in situ cases, which proves that the new approach can provide accuracy prediction of friction resistance for slurry pipe jacking with various soil conditions, and it may help for better future design and less construction costs.

scholarly journals Prediction of Friction Resistance for Slurry Pipe Jacking

2019 ◽  
Vol 10 (1) ◽  
pp. 207
Author(s):  
Yichao Ye ◽  
Limin Peng ◽  
Yang Zhou ◽  
Weichao Yang ◽  
Chenghua Shi ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Friction Coefficient ◽  
Normal Force ◽  
Design Parameters ◽  
Soil Slurry ◽  
New Approach ◽  
New Model ◽  
Friction Resistance ◽  
Pipe Jacking ◽  
Effective Friction

Friction resistance usually constitutes one of the two main components for the calculation of required jacking force. This paper provides a new approach to predict the friction resistance of slurry pipe jacking. First, the existing prediction equations and their establishment methods and essential hypotheses used were carefully summarized and compared, providing good foundations for the establishment of the new model. It was found that the friction resistance can be uniformly calculated by multiplying an effective friction coefficient and the normal force acting on the external surface of the pipe. This effective friction coefficient is introduced to reflect the effect of contact state of pipe-soil-slurry, highly affected by the effect of lubrication and the interaction of pipe-soil-slurry. The critical quantity of pipe-soil contact angle (or width) involved may be calculated by Persson’s contact model. Then, the equation of normal force was rederived and determined, in which the vertical soil stress should be calculated by Terzaghi’s silo model with parameters proposed by the UK Pipe Jacking Association. Different from the existing prediction models, this new approach has taken into full consideration the effect of lubrication, soil properties (such as internal friction angle, cohesion, and void ratio), and design parameters (such as buried depth, overcut, and pipe diameter). In addition, four field cases and a numerical simulation case with various soils and design parameters were carefully selected to check out the capability of the new model. There was greater satisfaction with the measured data as compared to the existing models and the numerical simulation approach, indicating that the new approach not only has higher accuracy but is also more flexible and has a wider applicability. Finally, the influence of buried depth, overcut, and pipe diameter on the friction resistance and lubrication efficiency were analyzed, and the results can be helpful for the future design.

Rolling Contact Between Rigid Cylinder and Semi-Infinite Elastic Body With Sliding and Adhesion

2007 ◽  
Vol 129 (3) ◽  
pp. 481-494 ◽  
Author(s):  
S. Hao ◽  
L. M. Keer
Keyword(s):  
Friction Coefficient ◽  
Normal Force ◽  
Analytic Solutions ◽  
Rolling Contact ◽  
Resistance Force ◽  
Surface Adhesion ◽  
Friction Resistance ◽  
Rigid Cylinder ◽  
Steady State Rolling ◽  
Adhesion Friction

Based on a hybrid superposition of an indentation contact and a rolling contact an analytical procedure is developed to evaluate the effects of surface adhesion during steady-state rolling contact, whereby two analytic solutions have been obtained. The first solution is a Hertz-type rolling contact between a rigid cylinder and a plane strain semi-infinite elastic substrate with finite adhesion, which is a JKR-type rolling contact but without singular adhesive traction at the edges of the contact zone. The second solution is of a rolling contact with JKR singular adhesive traction. The theoretical solution indicates that, when surface adhesion exists, the friction resistance can be significant provided the external normal force is small. In addition to the conventional friction coefficient, the ratio between friction resistance force and normal force, this paper suggests an “adhesion friction coefficient” which is defined as the ratio between friction resistance force and the sum of the normal force and a function of maximum adhesive traction per unit area, elastic constant of the substrate, and contact area that is characterized by the curvature of the roller surface.

Infuence of the Friction Force, the Tooth Correction Coefficient and the Normal Force Radial Component in the Form Factor and the Stress in the Feet of Spur Gear’s Teeth

2005 ◽  
Author(s):  
Aisman Quinones ◽  
Rafael Goytisolo ◽  
Jorge Moya ◽  
Roger Ocampo
Keyword(s):  
Form Factor ◽  
Friction Coefficient ◽  
Friction Force ◽  
Stress Fracture ◽  
Normal Force ◽  
Radial Component ◽  
Simultaneous Action ◽  
Favourable Effect ◽  
Correction Coefficient ◽  
Number Of Teeth

In this paper, a theoretical research is made on the influence of the friction force, the correction coefficient of the tooth and the radial component of the normal force in the Form Factor applicable to the stress on spur gears’ teeth. The Industrial Standards AGMA, ISO and DIN use the Lewis factor as the Form Factor but it doesn’t consider the above mentioned effects. The Standard GOST uses a Form Factor that considers the effect of the correction coefficient of the tooth and the radial component of the normal strength, but it doesn’t include the effect of the friction force. In this paper, a Mathematical Model is developed that incorporates all those effects. The obtained values of the form factors were represented graphically in function of the number of teeth, the correction coefficient and the friction coefficient. A graph is drawn for the driver gear and the driven gear, in which a remarkable influence of the simultaneous action of friction and correction coefficients is appreciated. In this new approach, it is found that the correction coefficients needed to optimize the resistance to the stress fracture of the teeth, in dependence of the values of the friction coefficient, should be greater that those used in the traditional approach. On the other hand, it has always been considered that gears with small number of teeth are the weakest with respect to stress fracture; however, in multiplying transmissions it is possible for driver gears with high number of teeth to be the weakest gear, given the favourable effect of the friction force on Form Factor in the driven gear and unfavourable in the driver gear. For the validation of the obtained results the Program of Finite Elements Analysis COSMOS Design Start 4.0 was used, obtaining very good results. Using FEA and Multiple Lineal Regression, a new expression for the calculation of the stress concentration coefficient in the feet of the tooth, in function of the number of teeth and of the correction coefficient, was found: kσMEF=1.497+0.126−0.003933Z

Influence of Vibration on Interface Friction of Pile-Soil System

2011 ◽  
Vol 243-249 ◽  
pp. 6079-6082
Author(s):  
Xiao Peng Li ◽  
Tao Li ◽  
Ze Liang Duan ◽  
Bang Chun Wen
Keyword(s):  
Friction Coefficient ◽  
Friction Reduction ◽  
Structure Parameters ◽  
Vibration Acceleration ◽  
Soil System ◽  
Interface Friction ◽  
Soil Particles ◽  
Friction Resistance ◽  
Change Tendency ◽  
Effective Friction

Based on the model of effective friction coefficient, the change tendency of effective friction coefficient under different harmonic forces and the method of improving its decrease rate have been studied. The model of vibratory piling machine has been taken as a research object for friction reduction, and the stress of soil particles and the situation of friction resistance on pile surface have been analyzed while sinking the pile. The effect on interface friction of pile-soil system under vibration, caused by the depth of pile sinking, pile structure parameters and vibration acceleration, has also been studied, so that an effective method of decreasing interface friction can be found. Thus, the sinking efficiency would be improved by being analyzed, evaluated and parameter optimized.

Effect of shape/size and distribution of microgeometries of textures on tribo-performance of crankpin bearing

2021 ◽  
pp. 135065012110105
Author(s):  
Nguyen Van Liem ◽  
Wu Zhenpeng ◽  
Jiao Renqiang
Keyword(s):  
Friction Coefficient ◽  
Friction Force ◽  
Contact Force ◽  
Distribution Density ◽  
Hydrodynamic Lubrication ◽  
Operating Conditions ◽  
Asperity Contact ◽  
Combined Model ◽  
Obvious Effect ◽  
Area Density

The effect of the shape/size and distribution of microgeometries of textures on improving the tribo-performance of crankpin bearing is proposed. Based on a combined model of the slider-crank mechanism dynamic and hydrodynamic lubrication, the distribution density, area density, and shape of spherical textures, square-cylindrical textures, wedge-shaped textures, and a hybrid between spherical texture and square-cylindrical texture on the crankpin bearing's tribo-performance are investigated under different operating conditions of the engine. The tribological characteristic of the crankpin bearing is then evaluated via the indexes of the oil film pressure p, asperity contact force, friction force, and friction coefficient of the crankpin bearing. The research results show that the distribution density with n = 12 and m = 6, and area density with α = 30% of various microtextures have an obvious effect on ameliorating the crankpin bearings tribo-performance. Concurrently, at the mixed lubrication region, the shape of the square-cylindrical texture on improving the tribo-performance is better than the other shapes of the spherical texture, wedge-shaped texture, and spherical and square-cylindrical texture. Particularly, all the average values of the asperity contact force, friction force, and friction coefficient with a square-cylindrical texture are significantly reduced by 14.6%, 19.5%, and 34.5%, respectively, in comparison without microtextures. Therefore, the microtextures of the spherical texture applied on the bearing surface can contribute to enhance the durability and decrease the friction power loss of the engine.

scholarly journals Design of an Ultra-Wideband Microstrip-to-Slotline Transition on Low-Permittivity Substrate

Electronics ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 1329
Author(s):  
Jung Seok Lee ◽  
Gwan Hui Lee ◽  
Wahab Mohyuddin ◽  
Hyun Chul Choi ◽  
Kang Wook Kim
Keyword(s):  
Microstrip Line ◽  
Return Loss ◽  
Analytical Formula ◽  
Parameter Tuning ◽  
Ultra Wideband ◽  
Design Parameters ◽  
Analytical Line ◽  
Cross Sectional ◽  
Analysis And Design ◽  
Low Permittivity

Analysis and design of an ultra-wideband microstrip-to-slotline transition on a low permittivity substrate is presented. Cross-sectional structures along the proposed transition are analyzed using conformal mapping assuming quasi-TEM modes, attaining one analytical line impedance formula with varying design parameters. Although the slotline is a non-TEM transmission line, the transitional structures are configured to have quasi-TEM modes before forming into the slotline. The line impedance is optimally tapered using the Klopfenstein taper, and the electric field shapes are smoothly transformed from microstrip line to slotline. The analytical formula is accurate within 5% difference, and the final transition configuration can be designed without parameter tuning. The implemented microstrip-to-slotline transition possesses insertion loss of less than 1.5 dB per transition and return loss of more than 10 dB from 4.4 to over 40 GHz.

A novel technique for modeling friction behavior in knitted fabric simulation

2017 ◽  
Vol 29 (6) ◽  
pp. 776-792
Author(s):  
Vajiha Mozafary ◽  
Pedram Payvandy
Keyword(s):  
Friction Coefficient ◽  
Uniform Distribution ◽  
Friction Force ◽  
Experimental Result ◽  
Knitted Fabric ◽  
Friction Behavior ◽  
Content Type ◽  
Novel Technique ◽  
Fabric Structure ◽  
Fabric Surface

Purpose Fabric-object friction force is a fundamental factor in cloth simulation. A large number of parameters influence the frictional properties of fabrics such as fabric structure, yarn structure, and inherent properties of component fibers. The purpose of this paper is to propose a novel technique for modeling fabric-object friction force in knitted fabric simulation based on the mass spring model. Design/methodology/approach In this technique, unlike other studies, distribution of friction coefficient over the fabric surface is not uniform and depends on the fabric structure. The main reason for considering non-uniform distribution is that in various segments of fabric, contact percent of fabric-object is different. Findings The proposed technique and common methods based on friction coefficient uniform distribution are used to simulate the frictional behavior of knitted fabrics. The results show that simulation error values for proposed technique and common methods are 2.7 and 9.4 percent as compared with the experimental result, respectively. Originality/value In the existing methods of the friction force modeling, the friction coefficient of fabric is assumed uniform. But this assumption is not correct because fabric does not have an isotropic structure. Thus in this study, the friction coefficient distribution is considered based on fabric structure to achieve more of realistic simulations.

scholarly journals A thermal resistances-based approach for thermal-elastohydrodynamic calculations in point contacts

2017 ◽  
Vol 232 (11) ◽  
pp. 2088-2102 ◽  
Author(s):  
Eduardo de la Guerra Ochoa ◽  
Javier Echávarri Otero ◽  
Enrique Chacón Tanarro ◽  
Benito del Río López
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Thermal Effects ◽  
Good Accuracy ◽  
Computational Cost ◽  
Point Contact ◽  
Elastohydrodynamic Lubrication ◽  
Point Contacts ◽  
New Approach ◽  
Ball On Disc

This article presents a thermal resistances-based approach for solving the thermal-elastohydrodynamic lubrication problem in point contact, taking the lubricant rheology into account. The friction coefficient in the contact is estimated, along with the distribution of both film thickness and temperature. A commercial tribometer is used in order to measure the friction coefficient at a ball-on-disc point contact lubricated with a polyalphaolefin base. These data and other experimental results available in the bibliography are compared to those obtained by using the proposed methodology, and thermal effects are analysed. The new approach shows good accuracy for predicting the friction coefficient and requires less computational cost than full thermal-elastohydrodynamic simulations.

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