Kinematics and Efficiency Analysis of the Planetary Roller Screw Mechanism

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Steven A. Velinsky ◽  
Baeksuk Chu ◽  
Ty A. Lasky
Keyword(s):  
Elastic Deformation ◽  
Carrying Capacity ◽  
Kinematic Analysis ◽  
Efficiency Analysis ◽  
Ball Screw ◽  
Load Carrying Capacity ◽  
Equilibrium Conditions ◽  
Load Carrying ◽  
Roller Screw ◽  
Screw Mechanism

This paper analyzes the kinematics and the efficiency of the planetary roller screw mechanism (RSM) to provide a fundamental basis to support its various applications. The mechanical structure and practical advantages are presented in comparison with the conventional ball screw mechanism (BSM). Kinematic analysis involves derivation of the angular and axial motions, as well as the development of the slip pattern between the contacting components. Results show that for any motion of the RSM slip always occurs. Kinematic analysis including elastic deformation is also presented. The load carrying capacity and efficiency of the RSM are derived based on geometric and equilibrium conditions, and the results are compared with the BSM.

scholarly journals Contact Analysis and Static Load Carrying Capacity of Planetary Roller Screw Mechanism

2020 ◽  
Author(s):  
Nam Su Kim ◽  
Kyongho Kim ◽  
Sinhyok Jong
Keyword(s):  
Finite Element ◽  
Contact Stress ◽  
Carrying Capacity ◽  
Static Load ◽  
Load Capacity ◽  
Load Carrying Capacity ◽  
Elastic Plastic ◽  
Load Carrying ◽  
Roller Screw ◽  
Screw Mechanism

Abstract This paper aims to investigate the contact characteristics and static load carrying capacity of planetary roller screw mechanism (PRSM). Compared to the ball screw mechanism, the advantages of the PRSM are high stiffness, high load capacity, long travel life and compact structure, etc., since the PRSM possesses more contact points than ball screws in a comparable size. The actuated load is carried through the threaded surface contacts of the screw, the rollers and the nut and the contact characteristics of these components are very important for studying the wear, transmission accuracy and efficiency of a PRSM. Prior work has neglected to take a fundamental approach towards understanding the elastic-plastic contact characteristics of threaded surfaces under high loads and it is closely related to the static load carrying capacity of PRSM. Accordingly, in this paper, the contact characteristics of PRSM under the different working loads are modeled based on Hertz contact theory and the calculation formulas between normal force of thread turns and the elastic-plastic contact stress and deformation are derived. Then, it goes further to derive a calculation method of static load carrying capacity of PRSM based on simplified model of static load distribution. Finally, a verification model is developed by finite element method (FEM) to perform contact stress and strain analysis of PRSM. Besides, through the comparison of the results between the theory model and ANSYS Workbench finite element model verify the reliability of the theory.

Deformation Effects on the Load Carrying Capacity of the Barrel Bearing in Axial Piston Pumps and Motors

2006 ◽  
Author(s):  
Peter A. J. Achten ◽  
Marc P. A. Schellekens
Keyword(s):  
Elastic Deformation ◽  
Carrying Capacity ◽  
Thrust Bearing ◽  
Pressure Profile ◽  
Load Carrying Capacity ◽  
Axial Piston Pumps ◽  
Load Carrying ◽  
Face Seals ◽  
Axial Piston Machine ◽  
Axial Piston

Most hydrostatic pumps and motors apply mechanical face seals, often also acting as a thrust bearing. The load carrying capacity of these bearings is very much dependent on the pressure profile generated in the sealing gap. Previous research, outside pumps and motors, has already shown that the gap pressure profile is largely influenced by small radial deformations of the seal lands. This paper discusses the elastic deformation of pump components and the effects of these deformations on the load carrying capacity of a barrel in an axial piston machine.

Effect of surface roughness and elastic deformation on the performance of a magnetic fluid-based squeeze film in rotating porous annular plates

2014 ◽  
Vol 66 (3) ◽  
pp. 490-497
Author(s):  
Mukesh E. Shimpi ◽  
Gunamani Deheri
Keyword(s):  
Elastic Deformation ◽  
Magnetic Fluid ◽  
Carrying Capacity ◽  
Type Equation ◽  
Squeeze Film ◽  
Rotational Inertia ◽  
Load Carrying Capacity ◽  
Content Type ◽  
Annular Plates ◽  
Load Carrying

Purpose – The purpose of this paper is to study and analyse the behaviour of a magnetic fluid-based squeeze film between rotating transversely rough porous annular plates, taking the elastic deformation into consideration. Design/methodology/approach – The stochastic film thickness characterizing the roughness is considered to be asymmetric with non-zero mean and variance and skewness while a magnetic fluid is taken as the lubricant. The associated stochastically averaged Reynolds-type equation is solved with appropriate boundary conditions to obtain the pressure distribution, which in turn is used to derive the expression for the load-carrying capacity. Findings – It is observed that the roughness of the bearing surfaces affects the performance adversely, although the bearing registers an improved performance owing to the magnetic fluid lubricant. Also, it is seen that the deformation causes reduced load-carrying capacity. The bearing can support a load even in the absence of flow, unlike the case of conventional lubricants. Originality/value – The originality of the paper lies in the fact that the negative effect of porosity, deformation and standard deviation can be minimized to some extent by the positive effect of the magnetic fluid lubricant in the case of negatively skewed roughness by suitably choosing the rotational inertia and aspect ratio. This effect becomes sharper when negative variance occurs.

Elastic Deformation Effects on the Thermo-Hydrodynamic Aspect of Porous Journal Bearings

2014 ◽  
Vol 353 ◽  
pp. 275-279
Author(s):  
S. Boubendir ◽  
Salah Larbi ◽  
R. Bennacer
Keyword(s):  
Elastic Deformation ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Maximum Pressure ◽  
Load Carrying Capacity ◽  
Static Characteristics ◽  
Governing Equations ◽  
Load Carrying ◽  
Variation Parameter ◽  
Viscosity Variation

In this paper, the effects of porous bush elastic deformation on the static characteristics of finite porous journal bearing are investigated using Darcy’s law. The modified Reynolds equation applied to thermo-hydrodynamic problems is modified by considering the viscosity variation along the film thickness. The film pressure distribution and other characteristics such as the load carrying capacity and attitude angle are obtained by solving the governing equations numerically. Obtained results showed that deformation is considerable in the maximum pressure zone, and the elastic deformation will decrease the load carrying capacity. The viscosity variation parameter tends also to decrease the load carrying capacity.

Steady-state performance of a circular journal bearing lubricated with a non-Newtonian fluid considering the elastic deformation of the liner

2019 ◽  
Vol 233 (9) ◽  
pp. 1389-1396
Author(s):  
Boualem Chetti ◽  
Hamid Zouggar
Keyword(s):  
Friction Coefficient ◽  
Elastic Deformation ◽  
Power Law ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Load Carrying Capacity ◽  
Static Characteristics ◽  
Load Carrying ◽  
Power Law Index

In this work, a numerical study of the effect of elastic deformation on the static characteristics of a circular journal bearing operating with non-Newtonian fluids obeying to the power law model is presented. The modified Reynolds equation has been derived taking into consideration the effect of non-Newtonian behavior of the fluids. To obtain the pressure distribution, the Reynolds equation has been solved using finite difference technique with appropriate iterative technique incorporating Reynolds boundary conditions. The static performance characteristics for finite-width journal bearing in terms of the load-carrying capacity, the attitude angle, friction coefficient, and the side leakage have been studied for various values of the non-Newtonian power law index n and the elastic coefficient. The results show that the increase of the power law index produces a higher load-carrying capacity, a higher side leakage, a lower attitude angle, and a lower friction coefficient. From this study, it can be concluded that the elastic deformation has an important influence on the static characteristics of the journal bearing lubricated with a non-Newtonian fluid, and this influence is more significant for the journal bearing operating at larger values of the eccentricity ratio.

scholarly journals Magnetic Fluid-Based Squeeze Film Behaviour in Curved Porous-Rotating Rough Annular Plates and Elastic Deformation Effect

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
M. E. Shimpi ◽  
G. M. Deheri
Keyword(s):  
Elastic Deformation ◽  
Magnetic Fluid ◽  
Carrying Capacity ◽  
Random Variable ◽  
Squeeze Film ◽  
Rotational Inertia ◽  
Load Carrying Capacity ◽  
Annular Plates ◽  
Load Carrying ◽  
Transverse Roughness

Efforts have been directed to study and analyze the squeeze film performance between rotating transversely rough curved porous annular plates in the presence of a magnetic fluid lubricant considering the effect of elastic deformation. A stochastic random variable with nonzero mean, variance, and skewness characterizes the random roughness of the bearing surfaces. With the aid of suitable boundary conditions, the associated stochastically averaged Reynolds' equation is solved to obtain the pressure distribution in turn, which results in the calculation of the load-carrying capacity. The graphical representations establish that the transverse roughness, in general, adversely affects the performance characteristics. However, the magnetization registers a relatively improved performance. It is found that the deformation causes reduced load-carrying capacity which gets further decreased by the porosity. This investigation tends to indicate that the adverse effect of porosity, standard deviation and deformation can be compensated to certain extent by the positive effect of the magnetic fluid lubricant in the case of negatively skewed roughness by choosing the rotational inertia and the aspect ratio, especially for suitable ratio of curvature parameters.

The Effect of Elastic Deformation on the Load-Carrying Capacity of Textured Sliding Surfaces

2015 ◽  
Vol 736 ◽  
pp. 7-12
Author(s):  
Bo Zhang ◽  
Jing Qiu Wang ◽  
Xiao Lei Wang
Keyword(s):  
Numerical Simulation ◽  
Elastic Modulus ◽  
Elastic Deformation ◽  
Surface Texture ◽  
Carrying Capacity ◽  
Simulation Analysis ◽  
Soft Materials ◽  
Load Carrying Capacity ◽  
Sliding Surfaces ◽  
Load Carrying

In order to study the differences in load-carrying capacity of surface-textured soft materials and stiff materials, a theoretical hydrodynamic model considering elastic deformation is developed for numerical simulation analysis. Minimum oil film thickness at a certain load is computed as an index to evaluate the load-carrying capacity of textured sliding surfaces made of soft materials and stiff materials. The results show that the elastic modulus affects greatly on the load-carrying capacity. In the case of the surface texture with a dimple aspect of 0.05, textured soft materials has a higher load-carrying capacity than that of the stiff materials. In the case of the surface texture with a dimple aspect of 0.01 and only under high loads, textured stiff materials provides a better load-carrying capacity than that of the soft materials.

Analysis of a circular journal bearing lubricated with micropolar fluids including EHD effects

2014 ◽  
Vol 66 (2) ◽  
pp. 168-173 ◽  
Author(s):  
Boualem Chetti
Keyword(s):  
Elastic Deformation ◽  
Carrying Capacity ◽  
Reynolds Equation ◽  
Journal Bearing ◽  
Newtonian Fluids ◽  
Load Carrying Capacity ◽  
Micropolar Fluids ◽  
Content Type ◽  
Load Carrying ◽  
Modified Reynolds Equation

Purpose – The performance of finite circular journal bearing lubricated with micropolar fluids taking into account the elastic deformation of the bearing liner is presented. The paper aims to discuss these issues. Design/methodology/approach – The modified Reynolds equation is obtained using the micropolar lubrication theory. The solution of the modified Reynolds equation is determined using finite difference technique. The static characteristics in terms of load-carrying capacity, attitude angle, side leakage and friction coefficient for micropolar and Newtonian fluids are determined for various values of eccentricity ratio and different values of elastic coefficient. Findings – Compared with Newtonian fluids, the micropolar fluids produce an increase in the load-carrying capacity and a reduction in the attitude angle, the friction factor and side leakage for both the rigid and deformable bearings. Originality/value – It is concluded that the influence of elastic deformation on the bearing characteristics lubricated with micropolar fluids is significantly apparent compared with bearing lubricated with Newtonian fluids.

Influence of Yield Strength Variability over Cross-Section to Steel Beam Load-Carrying Capacity

2005 ◽  
Vol 10 (2) ◽  
pp. 151-160 ◽  
Author(s):  
J. Kala ◽  
Z. Kala
Keyword(s):  
Yield Strength ◽  
Cross Section ◽  
Carrying Capacity ◽  
Bending Moment ◽  
Statistical Characteristics ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Strength Variability ◽  
Hot Rolled ◽  
Hot Rolled Steel

Authors of article analysed influence of variability of yield strength over cross-section of hot rolled steel member to its load-carrying capacity. In calculation models, the yield strength is usually taken as constant. But yield strength of a steel hot-rolled beam is generally a random quantity. Not only the whole beam but also its parts have slightly different material characteristics. According to the results of more accurate measurements, the statistical characteristics of the material taken from various cross-section points (e.g. from a web and a flange) are, however, more or less different. This variation is described by one dimensional random field. The load-carrying capacity of the beam IPE300 under bending moment at its ends with the lateral buckling influence included is analysed, nondimensional slenderness according to EC3 is λ¯ = 0.6. For this relatively low slender beam the influence of the yield strength on the load-carrying capacity is large. Also the influence of all the other imperfections as accurately as possible, the load-carrying capacity was determined by geometrically and materially nonlinear solution of very accurate FEM model by the ANSYS programme.

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