A constitutive model for entangled polydisperse linear flexible polymers with entanglement dynamics and a configuration dependent friction coefficient. Part I: Model derivation

2018 ◽  
Vol 62 (1) ◽  
pp. 121-134 ◽  
Author(s):  
D. W. Mead ◽  
S. Monjezi ◽  
J. Park
Keyword(s):  
Friction Coefficient ◽  
Constitutive Model ◽  
Entanglement Dynamics ◽  
Flexible Polymers ◽  
Model Derivation

scholarly journals Sensitivity Analysis of Johnson-Cook Material Constants and Friction Coefficient Influence on Finite Element Simulation of Turning Inconel 718

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3121 ◽  
Author(s):  
Xiaoli Qiu ◽  
Xianqiang Cheng ◽  
Penghao Dong ◽  
Huachen Peng ◽  
Yan Xing ◽  
...  
Keyword(s):  
Residual Stress ◽  
Sensitivity Analysis ◽  
Finite Element ◽  
Friction Coefficient ◽  
Constitutive Model ◽  
Cutting Force ◽  
Inconel 718 ◽  
Coulomb Friction ◽  
Cutting Conditions ◽  
Simulation Results

The Johnson-Cook (J-C) constitutive model, including five material constants (A, B, n, C, m), and the Coulomb friction coefficient (μ) are critical preprocessed data in machining simulations. Before they become reliable preprocessed data, investigating these parameters’ effect on simulation results benefits parameter-selecting. This paper aims to investigate the different influence of five settings of the J-C constitutive equation and Coulomb friction coefficient on the turning simulation results of Inconel 718 under low-high cutting conditions, including residual stress, chip morphology, cutting force and temperature. A three-dimensional (3-D) finite element model was built, meanwhile, the reliability of the model was verified by comparing the experiment with the simulation. Sensitivity analysis of J-C parameters and friction coefficient on simulation results at low-high cutting conditions was carried out by the hybrid orthogonal test. The results demonstrate that the simulation accuracy of Inconel 718 is more susceptible to strain hardening and thermal softening in the J-C constitutive model. The friction coefficient only has significant effects on axial and radial forces in the high cutting condition. The influences of the coefficient A, n, and m on the residual stress, chip thickness, cutting force and temperature are especially significant. As the cutting parameters increase, the effect of the three coefficients will change visibly. This paper provides direction for controlling simulation results through the adjustment of the J-C constitutive model of Inconel 718 and the friction coefficient.

scholarly journals A constitutive model with microstructure evolution for flow of rate-independent granular materials

2011 ◽  
Vol 682 ◽  
pp. 590-616 ◽  
Author(s):  
JIN SUN ◽  
SANKARAN SUNDARESAN
Keyword(s):  
Friction Coefficient ◽  
Constitutive Model ◽  
Granular Materials ◽  
Simple Shear ◽  
Evolution Equations ◽  
Complex Loading ◽  
Dem Simulations ◽  
Particle Level ◽  
Complex Rheology ◽  
Using Data

A constitutive model is developed for the complex rheology of rate-independent granular materials. The closures for the pressure and the macroscopic friction coefficient are linked to microstructure through evolution equations for coordination number and fabric. The material constants in the model are functions of particle-level properties and are calibrated using data generated through simulations of steady and unsteady simple shear using the discrete element method (DEM). This model is verified against DEM simulations at complex loading conditions.

Research of Safe Speed at Snow on Freeway Based on Braking Model of Stopping Sight Distance

2012 ◽  
Vol 209-211 ◽  
pp. 837-840
Author(s):  
Jian Jun Wang ◽  
Fa Yao Xu ◽  
A Jin Ma
Keyword(s):  
Friction Coefficient ◽  
Surface Friction ◽  
Calculation Model ◽  
Driving Safety ◽  
Adhesion Coefficient ◽  
Distance Analysis ◽  
Sight Distance ◽  
Snow Condition ◽  
Model Derivation ◽  
Stopping Sight Distance

The brake model derivation based on the kinematics of the stopping sight distance analysis, considering the freeway visibility and road surface friction coefficient, put forward freeway safety speed calculation model in snow condition, reach maximum safe speed of snow freeway in a different visibility and road adhesion coefficient snow condition, provide a management reference for freeway snow driving safety.

scholarly journals A non-homogeneous constitutive model for human blood. Part 1. Model derivation and steady flow

2008 ◽  
Vol 617 ◽  
pp. 327-354 ◽  
Author(s):  
MIGUEL MOYERS-GONZALEZ ◽  
ROBERT G. OWENS ◽  
JIANNONG FANG
Keyword(s):  
Blood Flow ◽  
Cell Migration ◽  
Constitutive Model ◽  
Human Blood ◽  
Axisymmetric Flow ◽  
Healthy Human ◽  
Small Vessels ◽  
Model Derivation ◽  
Model Features ◽  
Fahraeus Effect

The earlier constitutive model of Fang & Owens (Biorheology, vol. 43, 2006, p. 637) and Owens (J. Non-Newtonian Fluid Mech. vol. 140, 2006, p. 57) is extended in scope to include non-homogeneous flows of healthy human blood. Application is made to steady axisymmetric flow in rigid-walled tubes. The new model features stress-induced cell migration in narrow tubes and accurately predicts the Fåhraeus–Lindqvist effect whereby the apparent viscosity of healthy blood decreases as a function of tube diameter in sufficiently small vessels. That this is due to the development of a slippage layer of cell-depleted fluid near the vessel walls and a decrease in the tube haematocrit is demonstrated from the numerical results. Although clearly influential, the reduction in tube haematocrit observed in small-vessel blood flow (the so-called Fåhraeus effect) does not therefore entirely explain the Fåhraeus–Lindqvist effect.

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