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.

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.

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.

scholarly journals A New Approach to Modeling Slip and Work Input for Centrifugal Compressors

2020 ◽  
Author(s):  
Herbert M. Harrison ◽  
Nicole L. Key
Keyword(s):  
Absolute Error ◽  
New Method ◽  
Design Parameters ◽  
Analysis Tool ◽  
New Approach ◽  
New Model ◽  
Error Band ◽  
Slip Factor ◽  
Work Input ◽  
Impeller Geometry

Abstract A new method of modeling slip factor and work input for centrifugal compressor impellers is presented. Rather than using geometry to predict the behavior of the flow at the impeller exit, the new method leverages governing relationships to predict the work input delivered by the impeller with dimensionless design parameters. The approach incorporates both impeller geometry and flow conditions and, therefore, is inherently able to predict the slip factor both at design and off-design conditions. Five impeller cases are used to demonstrate the efficacy of the method, four of which are well documented in the open literature. Multiple implementations of the model are introduced to enable users to customize the model to specific applications. Significant improvement in the accuracy of the prediction of slip factor and work input is obtained at both design and off-design conditions relative to Wiesner’s slip model. While Wiesner’s model predicts the slip factor of 52% of the data within ±0.05 absolute error, the most accurate implementation of the new model predicts 99% of the data within the same error band. The effects of external losses on the model are considered, and the new model is fairly insensitive to the effects of external losses. Finally, detailed procedures to incorporate the new model into a meanline analysis tool are provided in the appendices.

scholarly journals A New Approach to Modeling Slip and Work Input for Centrifugal Compressors

2020 ◽  
Author(s):  
Herbert Harrison ◽  
Nicole L. Key
Keyword(s):  
Absolute Error ◽  
New Method ◽  
Design Parameters ◽  
Analysis Tool ◽  
New Approach ◽  
New Model ◽  
Error Band ◽  
Slip Factor ◽  
Work Input ◽  
Impeller Geometry

Abstract A new method of modeling slip factor and work input for centrifugal compressor impellers is presented. Rather than using geometry to predict the behavior of the flow at the impeller exit, the new method leverages governing relationships to predict the work input delivered by the impeller with dimensionless design parameters. The approach incorporates both impeller geometry and flow conditions and, therefore, is inherently able to predict the slip factor both at design and off-design conditions. Five impeller cases are used to demonstrate the efficacy of the method, four of which are well documented in the open literature. Multiple implementations of the model are introduced to enable users to customize the model to specific applications. Significant improvement in the accuracy of the prediction of slip factor and work input is obtained at both design and off-design conditions relative to Wiesner's slip model. While Wiesner's model predicts the slip factor of 52% of the data within ±0.05 absolute error, the most accurate implementation of the new model predicts 99% of the data within the same error band. The effects of external losses on the model are considered, and the new model is fairly insensitive to the effects of external losses. Finally, detailed procedures to incorporate the new model into a meanline analysis tool are provided in the appendices.

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.

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.

An optimal wheel-torque control on a compliant modular robot for wheel-slip minimization

Robotica ◽  
2015 ◽  
Vol 35 (2) ◽  
pp. 463-482 ◽  
Author(s):  
Avinash Siravuru ◽  
Suril V. Shah ◽  
K. Madhava Krishna
Keyword(s):  
Friction Coefficient ◽  
Normal Force ◽  
Experimental Studies ◽  
Traction Force ◽  
Static Stability ◽  
Wheel Speed ◽  
Torque Control ◽  
Modular Robot ◽  
Wheel Slip ◽  
Wheel Torque

SUMMARYThis paper discusses the development of an optimal wheel-torque controller for a compliant modular robot. The wheel actuators are the only actively controllable elements in this robot. For this type of robots, wheel-slip could offer a lot of hindrance while traversing on uneven terrains. Therefore, an effective wheel-torque controller is desired that will also improve the wheel-odometry and minimize power consumption. In this work, an optimal wheel-torque controller is proposed that minimizes the traction-to-normal force ratios of all the wheels at every instant of its motion. This ensures that, at every wheel, the least traction force per unit normal force is applied to maintain static stability and desired wheel speed. The lower this is, in comparison to the actual friction coefficient of the wheel-ground interface, the more margin of slip-free motion the robot can have. This formalism best exploits the redundancy offered by a modularly designed robot. This is the key novelty of this work. Extensive numerical and experimental studies were carried out to validate this controller. The robot was tested on four different surfaces and we report an overall average slip reduction of 44% and mean wheel-torque reduction by 16%.

Heat Exchange Calculation of a Regenerative Air Heater with Numerical Simulation Method

2013 ◽  
Vol 860-863 ◽  
pp. 1416-1419
Author(s):  
Ri Guang Wei ◽  
Zhen Xiao Qu ◽  
Jian Qiang Gao
Keyword(s):  
Numerical Simulation ◽  
Simulation Method ◽  
Calculation Model ◽  
Design Parameters ◽  
Practical Calculation ◽  
Air Preheater ◽  
Air Heater ◽  
Pulverized Coal Boiler ◽  
Set Up ◽  
Coal Boiler

According to the structure and working principle of rotary air preheater,the heat transfer calculation model is set up with reasonable simplification. Combining with the design parameters of the rotary air preheater of a 400 t/h pulverized coal boiler unit ,the results of practical calculation show that the said thermodynamic calculation method not only has higher precision of calculation,but also can get the temperature distributions of the gas, air and heat surface in each cross-section of the rotary air preheater. The result of numerical simulation calculation tallies well with the original designed data. It can be used for the heat calculation both two-sectorial and three-sectorial air heater; it can be used for performance analysis of the regenerative air heater.

A Self-Actuating Traction-Drive Speed Reducer

2004 ◽  
Vol 127 (4) ◽  
pp. 631-636 ◽  
Author(s):  
Donald R. Flugrad ◽  
Abir Z. Qamhiyah
Keyword(s):  
Friction Coefficient ◽  
Normal Force ◽  
Drive System ◽  
Traction Drive ◽  
Sliding Motion ◽  
Output Torque ◽  
Speed Reducer ◽  
Rolling Elements ◽  
Drive Speed ◽  
High Output

Traction-drive speed reducers offer certain advantages over geared speed reducers. In particular, they generally run quieter than geared units and provide an opportunity for higher efficiency by eliminating sliding motion between contacting elements. In order to generate a sufficiently high output torque, some means must be provided to create a normal force between the rolling elements. This normal force, along with the friction coefficient, enables the device to transmit torque from one rolling member to the next. The speed reducer proposed here is designed so that the configuration of the rolling elements creates the needed normal force in response to the torque exerted back on the system by the downstream loading. Thus the device is self-actuating. Since the normal force is only present when needed, the rolling elements of the device can readily be disengaged, thus eliminating the need for a separate clutch in the drive system. This feature can be exploited to design a transmission with several distinct speed ratios that can be engaged and disengaged in response to changing speed requirements.

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