scholarly journals Briquetting of structurally inhomogeneous porous materials

2020 ◽  
Vol 65 (2) ◽  
pp. 205-214
Author(s):  
O. M. Dyakonov
Keyword(s):  
Porous Body ◽  
Pressure Coefficient ◽  
Energy Condition ◽  
Contact Friction ◽  
Equilibrium Equations ◽  
Friction Forces ◽  
Pressing Process ◽  
Deformation Work ◽  
Pressure Stress ◽  
Force Calculation

The work is devoted to solving the axisymmetric problem of the theory of pressing porous bodies with practical application in the form of force calculation of metallurgical processes of briquetting small fractional bulk materials: powder, chip, granulated and other metalworking wastes. For such materials, the shape of the particles (structural elements) is not geometrically correct or generally definable. This was the basis for the decision to be based on the continual model of a porous body. As a result of bringing this model to a two-dimensional spatial model, a closed analytical solution was obtained by the method of jointly solving differential equilibrium equations and the Guber–Mises energy condition of plasticity. The following assumptions were adopted as working hypotheses: the normal radial stress is equal to the tangential one, the lateral pressure coefficient is equal to the relative density of the compact. Due to the fact that the problem is solved in a general form and in a general formulation, the solution itself should be considered as methodological for any axisymmetric loading scheme. The transcendental equations of the deformation compaction of a porous body are obtained both for an ideal pressing process and taking into account contact friction forces. As a result of the development of a method for solving these equations, the formulas for calculating the local characteristics of the stressed state of the pressing, as well as the integral parameters of the pressing process are derived: pressure, stress, and deformation work.

scholarly journals Force calculation of the process of briquetting powder, chip and other bulk materials

2019 ◽  
pp. 118-125
Author(s):  
O. M. Dyakonov
Keyword(s):  
Porous Body ◽  
Pressure Coefficient ◽  
Energy Condition ◽  
Contact Friction ◽  
Equilibrium Equations ◽  
Bulk Materials ◽  
Friction Forces ◽  
Pressing Process ◽  
Deformation Work ◽  
Force Calculation

The work is devoted to solving the axisymmetric problem of the theory of pressing porous bodies with practical application in the form of force calculation of metallurgical processes of briquetting small fractional bulk materials: powder, chip, granulated and other metalworking wastes. For such materials, the shape of the particles (structural elements) is not geometrically correct or generally definable. This was the basis for the decision to be based on the continual model of a porous body. As a result of bringing this model to a two-dimensional spatial model, a closed analytical solution was obtained by the method of jointly solving differential equilibrium equations and the Guber-Mises energy condition of plasticity. The following assumptions were adopted as working hypotheses: the radial shear stress is equal to the tangential one, the lateral pressure coefficient is equal to the relative density of the compact. Due to the fact that the problem is solved in a general form and in a general formulation, the solution itself should be considered as methodological for any axisymmetric loading scheme. The transcendental equations of the deformation compaction of a porous body are obtained both for an ideal pressing process and taking into account contact friction forces. As a result of the development of a method for solving these equations, the formulas for calculating the local characteristics of the stressed state of the pressing, as well as the integral parameters of the pressing process are derived: pressure, stress, and deformation work.

Dynamical Modeling of Gear Transmission Considering Gearbox Casing

2018 ◽  
Author(s):  
Yang Luo ◽  
Natalie Baddour ◽  
Ming Liang
Keyword(s):  
Dynamic Models ◽  
Signal Propagation ◽  
Gear Transmission ◽  
Gear System ◽  
Dynamical Model ◽  
Contact Friction ◽  
Dynamical Response ◽  
Dynamic Simulations ◽  
Friction Forces ◽  
Frequency Domains

Much research has been carried out to investigate the dynamical response of a gear system because of its importance on vibration feature analysis. It is well known that the gearbox casing is one of the most important components of the gear system and plays an important role in signal propagation. However, its effects have widely been neglected within the dynamic simulations and few dynamic models have considered the gearbox casing when modeling a gear transmission. This paper proposes a gear transmission dynamical model with the consideration of the effects of gearbox casing. The proposed dynamical model incorporates TVMS, a time-varying load sharing ratio, as well as dynamic tooth contact friction forces, friction moments and dynamic mesh damping coefficients. The proposed gear dynamical model is validated by comparison with responses obtained from experimental test rigs under different speed conditions. Comparisons indicate that the responses of the proposed dynamical model are consistent with experimental results, in both time and frequency domains under different rotation speeds.

The Decay of Highly Skewed Flows in Ducts

1975 ◽  
Vol 97 (1) ◽  
pp. 85-92 ◽  
Author(s):  
B. Quinn
Keyword(s):  
Velocity Profile ◽  
Pressure Coefficient ◽  
Point Of View ◽  
Local Pressure ◽  
Friction Forces ◽  
Arbitrary Section

The development of a very nonuniform or skewed velocity profile in passing through a diffuser has been examined from the point of view of velocity components induced by line vortices. Account is taken of the effect of dissipation and straining on the strengths of the vortices and the intensities of the induced velocities. Changes with the integrated momentum of the perturbation velocities contribute to the local pressure in the duct, or diffuser, along with friction forces and area changes. An expression is derived for the pressure coefficient of a highly skewed profile flowing through a duct of arbitrary section. The results of experiments with an ejector apparatus are presented and found to support the analytical conclusions. In contrast with slightly skewed flows, diffusion will not inhibit the decay of highly skewed profiles.

Experimental Validation of a 2D Bristle Friction Force Model

2010 ◽  
Author(s):  
Steven Fillmore ◽  
Jianxun Liang ◽  
Ou Ma
Keyword(s):  
Friction Model ◽  
Contact Friction ◽  
Force Model ◽  
Tangential Plane ◽  
Stick Slip ◽  
Friction Forces ◽  
Body Contact ◽  
Point Of Interest ◽  
Experimental Effort ◽  
Sliding Regimes

This paper describes an experimental effort designed to validate a general 2D bristle contact friction model. The model extends the 1D integrated bristle friction model to a 2D space by allowing the “bristle spring” to not only stretch along the direction of the bristle displacement but also rotate due to the instantaneous direction change of the velocity or motion trend in the common tangential plane of the contacting surfaces involved at the point of interest. The model is capable of simulating frictional behaviour in both sliding and sticking regimes occurring in general 3D rigid-body contact. With such an extension, the resulting friction model can be readily used to compute 3D contact friction forces in both sticking and sliding regimes. Two experiments were designed and implemented to validate the new 2D bristle model. The experiments were able to passively produce common frictional phenomena such as sliding, sticking, and stick-slip.

Effect of contact friction forces in compressive tests of specimens

1983 ◽  
Vol 15 (10) ◽  
pp. 1486-1487
Author(s):  
V. I. Koval' ◽  
Yu. B. Gnuchii ◽  
V. S. Morganyuk
Keyword(s):  
Contact Friction ◽  
Friction Forces ◽  
Compressive Tests

Intelligent Modeling of Contact Mechanics and Friction Dynamics

2005 ◽  
Author(s):  
R. Marumo
Keyword(s):  
Contact Mechanics ◽  
Dynamic Models ◽  
Sliding Friction ◽  
Dynamic Modelling ◽  
Contact Friction ◽  
Friction Forces ◽  
Intelligent Modeling ◽  
Adhesion Contact ◽  
Frictional Forces ◽  
Friction Dynamics

This paper considers the investigations into adhesion, contact mechanics metal erosion effects, wear and tare as a result of the effects of frictional forces. Mechanical components rely on friction for the transformation and delivery of energy from point A to point B. This requires the knowledge of combined energies as well as their associated dynamic models and ancillary parameters. Adhesion, contact, friction and wear are major problems limiting both the fabrication yield and lifetime of any devices. Since it is the area of real contact, which determines the sliding friction, adhesion interaction may strongly affect the friction force even when no adhesion can be detected in a pull-off experiment. Therefore a good scientific dynamic modelling of friction forces is a prerequisite for the understanding and monitoring of friction adverse effect on mechanical systems for good maintenance purposes.

Analysis of Circular Braiding Process, Part 2: Mechanics Analysis of the Circular Braiding Process and Experiment

1999 ◽  
Vol 121 (3) ◽  
pp. 351-359 ◽  
Author(s):  
Q. Zhang ◽  
D. Beale ◽  
R. M. Broughton ◽  
S. Adanur
Keyword(s):  
Algebraic Equation ◽  
Kinematic Analysis ◽  
Equilibrium Equations ◽  
Friction Forces ◽  
Final Structure ◽  
Mechanics Model ◽  
Mechanics Analysis ◽  
Newton Raphson ◽  
Braided Structure ◽  
Raphson Method

The final structure of a braid is a consequence of force interactions among yarns in the convergent zone. In Part 1, the influence of friction forces on the final braided structure was discussed via kinematic analysis. A transformation from a 3-D cone to a 2-D plane was made for the mechanics analysis. A mechanics model is proposed in this paper to determine the braid angle by considering interlacing forces. Equilibrium equations for the braiding process are deduced. A Newton-Raphson method is used to solve the nonlinear algebraic equation set. Experiments have been conducted to produce braids at different machine speeds and with different tensions, and reveal that the mechanics model is potentially a better predictor of final braid structure than the kinematic analysis.

A Numerical Analysis for Piston Skirts in Mixed Lubrication—Part I: Basic Modeling

1992 ◽  
Vol 114 (3) ◽  
pp. 553-562 ◽  
Author(s):  
Dong Zhu ◽  
Herbert S. Cheng ◽  
Takayuki Arai ◽  
Kyugo Hamai
Keyword(s):  
Surface Profile ◽  
Mixed Lubrication ◽  
Contact Friction ◽  
Thermal Distortion ◽  
Surface Waviness ◽  
Piston Motion ◽  
Friction Forces ◽  
Crack Angle ◽  
Piston Skirts ◽  
Cylinder Bore

This paper presents a mathematical model for piston skirts in mixed lubrication. It takes into account the effects of surface waviness, roughness, piston skirt surface profile, bulk elastic deformation and thermal distortion of both piston skirts and cylinder bore on piston motion, lubrication and friction. The corresponding computer program developed can be used to calculate the entire piston trajectory and the hydrodynamic and contact friction forces as functions of crack angle under engine running conditions. This paper is the first part of a series of two papers. It gives basic information and some preliminary results. The second part will include the major results and discussions, focused on the influences of elastic and thermal deformations.

Design of Three New Cam-Based Constant-Force Mechanisms

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Javier López-Martínez ◽  
Daniel García-Vallejo ◽  
Francisco Manuel Arrabal-Campos ◽  
Jose Manuel Garcia-Manrique
Keyword(s):  
Compliant Mechanisms ◽  
Rolling Friction ◽  
Design Guidelines ◽  
Design Parameters ◽  
Constant Force ◽  
Equilibrium Equations ◽  
Constant Input ◽  
Friction Forces ◽  
Input Force ◽  
Cam Profile

Constant-force mechanisms are designed to keep a constant or nearly constant input force along a prescribed stroke of the mechanism. The implementation of this kind of mechanisms has been approached in literature using compliant mechanisms or through a certain combination of springs and nonlinear transmissions. In this work, three new constant-force mechanisms based on the use of springs, rollers, and cams are presented and analyzed. The rolling friction forces between the rollers and the cam are included in the force equilibrium equations and considered in the integration of the cam profile. The influence of the friction force on the input force as well as the design parameters involved is studied based on numerical techniques and simulations. In fact, the results evidence that to obtain a precise constant-force mechanism, rolling friction forces must be considered in the cam profile definition. The main design guidelines for the three constant-force mechanisms proposed are described.

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