scholarly journals A Multiscale Accuracy Degradation Prediction Method of Planetary Roller Screw Mechanism Based on Fractal Theory Considering Thread Surface Roughness

2021 ◽  
Vol 5 (4) ◽  
pp. 237
Author(s):  
Junjie Meng ◽  
Xing Du ◽  
Yingming Li ◽  
Peng Chen ◽  
Fuchun Xia ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Adhesive Wear ◽  
Fractal Theory ◽  
Great Influence ◽  
Wear Volume ◽  
Wear Depth ◽  
Asperity Contact ◽  
Thread Surface ◽  
Roller Screw ◽  
Screw Mechanism

The wear problems are vital to the planetary roller screw mechanism (PRSM) as they have a great influence on transmission accuracy, working efficiency, and service life. However, the wear characteristics of the PRSM have been rarely investigated in the past. In this paper, a multiscale adhesive wear model is established by incorporating the effective wear coefficient and considering the thread surface roughness. The variation of surface roughness is characterized by the two-dimension Majumdar–Bhushan (MB) function. The multi-asperity contact regimes are used to estimate microcontact mechanics of the rough interface. Moreover, the influences of surface roughness, material properties, and working conditions on the wear depth and precision loss of the PRSM are studied in detail. The results reveal that as the surface roughness increases, the total actual contact area, wear depth, and precision loss rate rise. In addition, the adhesive wear increases with the growth of the axial load, and decreases with the increase in the material hardness and material elastic modulus ratio to a certain extent. The investigation opens up a theoretical methodology to predict the wear volume and precision loss with regard to thread surface roughness, which lays the foundation for the design, manufacturing, and application of the PRSM.

Dynamic Modeling of the Double-Nut Planetary Roller Screw Mechanism Considering Elastic Deformations

2021 ◽  
Author(s):  
Xiaojun Fu ◽  
Geng Liu ◽  
Xin Li ◽  
Ma Shangjun ◽  
Qiao Guan
Keyword(s):  
External Force ◽  
Load Distribution ◽  
Equations Of Motion ◽  
Great Influence ◽  
Compressive Force ◽  
Mass System ◽  
Elastic Deformations ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Nonlinear Equations Of Motion

Abstract With the rising application of double-nut Planetary Roller Screw Mechanism (PRSM) into industry, increasing comprehensive studies are required to identify the interactions among motion, forces and deformations of the mechanism. A dynamic model of the double-nut PRSM with considering elastic deformations is proposed in this paper. As preloads, inertial forces and elastic deformations have a great influence on the load distribution among threads, the double-nut PRSM is discretized into a spring-mass system. An adjacency matrix is introduced, which relates the elastic displacements of nodes and the deformations of elements in the spring-mass system. Then, the compressive force acting on the spacer is derived and the equations of load distribution are given. Considering both the equilibrium of forces and the compatibility of deformations, nonlinear equations of motion for the double-nut PRSM are developed. The effectiveness of the proposed model is verified by comparing dynamic characteristics and the load distribution among threads with those from the previously published models. Then, the dynamic analysis of a double-nut PRSM is carried out, when the rotational speed of the screw and the external force acting on the nut #2 are changed periodically. The results show that if the external force is increased, the preload of the nut #1 is decreased and that of the nut #2 is increased. Although the nominal radii of rollers are the same, the maximum contact force acting on the roller #2 is much larger than that of the roller #1.

Adhesive Wear Based on Accurate FEA Study of Asperity Contact and n-Point Asperity Model

2016 ◽  
Vol 4 (1) ◽  
pp. 1-24
Author(s):  
Ajay K. Waghmare ◽  
Prasanta Sahoo
Keyword(s):  
Adhesive Wear ◽  
Complete Solution ◽  
Wear Particle ◽  
Wear Volume ◽  
Asperity Contact ◽  
Wear Model ◽  
Element Analysis ◽  
Particle Generation ◽  
Elastic Plastic ◽  
Asperity Model

The paper describes a theoretical study of adhesive wear based on accurate finite element analysis (FEA) of elastic-plastic contact of single asperity and n-point asperity model. The wear model developed considers wear particle generation in whole range of deformation, ranging from fully elastic through elastic-plastic to fully plastic. Well defined adhesion index and plasticity index are used to study the prospective situations arising out of variation in load, material properties, and surface roughness. It is observed that the wear volume at particular level of separation increases with increase in plastic deformation and adhesion effect. Materials having higher tendency to adhesion show higher wear rate. Trend of the results obtained is found in line with the existing solutions which are modeled with conventional asperity concept. Inclusion of separate formulations for intermediate state of deformation of asperities which are based on accurate FEA study gives complete solution.

scholarly journals Energy-Based Modelling of Adhesive Wear in the Mixed Lubrication Regime

Lubricants ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 16 ◽  
Author(s):  
J. Torben Terwey ◽  
Mohamed Ali Fourati ◽  
Florian Pape ◽  
Gerhard Poll
Keyword(s):  
Contact Area ◽  
Adhesive Wear ◽  
Mixed Lubrication ◽  
Wear Volume ◽  
Real Surface ◽  
Wear Depth ◽  
Wear Coefficient ◽  
Lubrication Regime ◽  
Mixed Lubrication Regime

Adhesive wear in dry contacts is often described using the Archard or Fleischer model. Both provide equations for the determination of a wear volume, taking the load, the sliding path and a set of material parameters into account. While the Fleischer model is based on energetic approaches, the Archard formulation uses an empirical factor—the wear coefficient—describing the intensity of wear. Today, a numerical determination of the wear coefficient is already possible and both approaches can be deduced to a local accumulation of friction energy. The aim of this work is to enhance existing energy-based wear models into the mixed lubrication regime. Therefore, the pressure distribution within the contact area will be determined numerically taking real surface topographies into account. The emerging contact area will be divided into one part of solid and a second part of elastohydrodynamically lubricated (EHL) contacts. Based on the resulting pressure and shear stress distribution, the formation of micro cracks within the loaded volume will be described. Determining a critical number of load cycles for each asperity, a locally resolved wear coefficient will be derived and the local wear depth calculated.

scholarly journals Rigid-Body Dynamic Analysis of Multi-Stage Planetary Roller Screw Mechanism

2020 ◽  
Vol 38 (5) ◽  
pp. 1001-1009
Author(s):  
Xin Li ◽  
Geng Liu ◽  
Chunyu Song ◽  
Xiaojun Fu ◽  
Shangjun Ma ◽  
...  
Keyword(s):  
Rigid Body ◽  
Structural Characteristics ◽  
Great Influence ◽  
Body Motion ◽  
Motion Equations ◽  
Rigid Body Dynamic ◽  
Multi Stage ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Body Dynamic

Based on the structural characteristics of the multi-stage Planetary Roller Screw Mechanism (PRSM), the motion and force among the different stages are analyzed. In terms of the Newton's second law, the rigid-body motion equations of the multi-stage PRSM without considering the manufacturing and assembly errors are derived. Then, the method for solving the motion equations is given. The forces acting on the parts in the multi-stage PRSM and the motion of the mechanism can be obtained from the present rigid-body dynamic model. The influence of the friction coefficients among the different stages on the dynamic characteristics of the multi-stage PRSM is discussed. The results show that the forces acting on the first-stage PRSM are larger than that acting on the second-stage PRSM, although the nominal radius of the screw in the first-stage PRSM is smaller. The friction coefficient between the nut and the screw in the different stages has the great influence on the efficiency of multi-stages PRSM with small helix angles, while that among the screws in the different stages has the slight effect on the efficiency.

scholarly journals Simulation and Experimental Study on Wear of U-Shaped Rings of Power Connection Fittings under Strong Wind Environment

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 735
Author(s):  
Songchen Wang ◽  
Xianchen Yang ◽  
Xinmei Li ◽  
Cheng Chai ◽  
Gen Wang ◽  
...  
Keyword(s):  
Abrasive Wear ◽  
Adhesive Wear ◽  
Surface Hardness ◽  
Wear Depth ◽  
Strong Wind ◽  
Wear Model ◽  
Wind Environment ◽  
Simulation Results ◽  
Oxidation Wear ◽  
Good Agreement

The objective of this study was to investigate the wear characteristics of the U-shaped rings of power connection fittings, and to construct a wear failure prediction model of U-shaped rings in strong wind environments. First, the wear evolution and failure mechanism of U-shaped rings with different wear loads were studied by using a swinging wear tester. Then, based on the Archard wear model, the U-shaped ring wear was dynamically simulated in ABAQUS, via the Umeshmotion subroutine. The results indicated that the wear load has an important effect on the wear of the U-shaped ring. As the wear load increases, the surface hardness decreases, while plastic deformation layers increase. Furthermore, the wear mechanism transforms from adhesive wear, slight abrasive wear, and slight oxidation wear, to serious adhesive wear, abrasive wear, and oxidation wear with the increase of wear load. As plastic flow progresses, the dislocation density in ferrite increases, leading to dislocation plugs and cementite fractures. The simulation results of wear depth were in good agreement with the test value of, with an error of 1.56%.

Contact Analysis of a Smooth Ball on an Anisotropic Rough Surface

1994 ◽  
Vol 116 (4) ◽  
pp. 850-859 ◽  
Author(s):  
C. Y. Poon ◽  
R. S. Sayles
Keyword(s):  
Surface Roughness ◽  
Rough Surface ◽  
Stochastic Approach ◽  
Contact Analysis ◽  
Asperity Contact ◽  
Correlation Lengths ◽  
Real Contact ◽  
Rough Surface Contact ◽  
Contact Pressures ◽  
Contact Spots

The effects of surface roughness and waviness upon the real contact areas, gaps between contact spots, and asperity contact pressures were studied. The distribution of real areas, gaps, and contact pressures are presented for different surface roughness, σ and correlation lengths, β*. The load-area relationship is compared to Bush’s model of strongly anisotropic rough surface contact using a stochastic approach.

Experiment and Surface Roughness Prediction Model for Ti-6Al-4V in Abrasive Belt Grinding

2016 ◽  
Vol 1136 ◽  
pp. 42-47 ◽  
Author(s):  
Ya Xiong Chen ◽  
Yun Huang ◽  
Gui Jian Xiao ◽  
Gui Lin Chen ◽  
Zhi Wu Liu ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Great Influence ◽  
Grinding Force ◽  
Work Piece ◽  
Belt Grinding ◽  
Abrasive Belt ◽  
Belt Speed ◽  
Feeding Speed

In abrasive belt grinding, abrasive belt granularity, abrasive belt speed,feeding speed and grinding force have a great influence on the surface roughness. In order to predicate the surface roughness of Ti-6Al-4V,a response surface methodology are used to build the model to predict surface roughness,and the influence of various parameters on surface roughness was analysed. The research shows that with the abrasive belt granularity and abrasive belt speed increasing,the work piece surface roughness decreases;with the grinding force and feeding speed increasing,the work piece surface roughness increases. Through the test,the response surface methodology with high prediction accuracy,provides a theoretical basis for the reasonable selection of abrasive belt grinding parameters.

On the Corrosion Behavior of Refined Bio-Oil during Rubbing Process

2011 ◽  
Vol 130-134 ◽  
pp. 1310-1313
Author(s):  
Yu Fu Xu ◽  
Wen Dong Li ◽  
Xian Guo Hu ◽  
Qiong Jie Wang
Keyword(s):  
Surface Roughness ◽  
Corrosion Behavior ◽  
High Frequency ◽  
Energy Dispersive Spectrometer ◽  
Wear Depth ◽  
Chemical Structures ◽  
Bio Oil ◽  
Component Content ◽  
Acidic Component ◽  
Worn Surface

The corrosion behavior during friction of refined bio-oil by distillation process was evaluated by high frequency reciprocating test rig. Both scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used to investigate the morphology and active elements contents on the rubbed surface on steel disk. The chemical structures of the oils and the topography and surface roughness of the wear scar were also studied by FTIR and surface roughness tester as well, respectively. The experimental results showed that corrosion behavior of bio-oil was improved after refining since the wear depth was 3.75µm and the worn surface roughness was 0.172µm, while they were 12.5µm and 0.217µm before refining. It was concluded that corrosion degree of worn surface was decreased after the bio-oil was refined, which was ascribed to the decrease of the acidic component content after the refining process.

Lubricated Wear of Machinable Lithium Disilicate Glass Ceramic

2017 ◽  
Vol 739 ◽  
pp. 18-22
Author(s):  
Laura Elbourne-Binns ◽  
Juan Carlos Baena ◽  
Ling Yin ◽  
Zhong Xiao Peng
Keyword(s):  
Surface Roughness ◽  
Glass Ceramic ◽  
Sliding Friction ◽  
Surface Preparation ◽  
Lithium Disilicate ◽  
Wear Volume ◽  
Oral Environment ◽  
Dry Conditions ◽  
Applied Forces ◽  
Lubrication Conditions

An experimental investigation was performed to study the wear of a promising dental ceramic, i.e., machinable lithium disilicate glass ceramic, under lubrication conditions, in particular, to examine effects of the surface finish and applied load on wear. Our previous work has shown that a fine finish in a dry condition did not necessarily translate to the lowest wear volume due to changes in the dominant wear mechanisms. This study tested the ceramic specimens with four average surface roughness values of Sa = 143 nm, 217 nm, 353 nm, and 692 nm on a reciprocating sliding friction rig against alumina balls with two applied forces of 5 N and 25 N in a bath of distilled water. Comparing with the results obtained in the dry conditions, this study shows that surface roughness of approximately 200 nm may be suitable for surface preparation of crowns made from the material in the wet and dry wear conditions in the oral environment.

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