Research on the Mechanical Properties of a New “I” Type Double-Decker Ball Bearing

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Yili Zhu ◽  
Yongchun Zhang ◽  
Chaowu Jin
Keyword(s):  
Mechanical Model ◽  
Mechanical Characteristics ◽  
Ball Bearing ◽  
Calculation Model ◽  
Load Test ◽  
Centrifugal Forces ◽  
Test Rig ◽  
Double Decker ◽  
Bearing Load ◽  
Simulation Results

The new “I” type double-decker ball bearing (NITDDBB) with two inner contact ball bearings is proposed to improve the speed and load capability of the original I type double-decker ball bearing (OITDDBB). Based on the quasi-statics principle, the mechanical model of the NITDDBB is established and takes into consideration the radial load, axial load, and ball centrifugal forces, as well as the gyroscopic moments. The corresponding calculation model is established on the matlab platform. The mechanical characteristics of the NITDDBB are analyzed and compared with the OITDDBB and also with a single-decker ball bearing (SDBB). Finally, a bearing load test rig is designed and built to verify the simulation results. The results provide a theoretical and experimental basis for the application of the NITDDBB.

A Study on Gradient Polymer Materials Used as Damping Coatings: Focus on Free Damping Coatings

2000 ◽  
Author(s):  
C. Remillat ◽  
G. R. Tomlinson
Keyword(s):  
Mechanical Model ◽  
Mechanical Characteristics ◽  
Single Layer ◽  
Polymer Materials ◽  
Gradient Material ◽  
Free Layer ◽  
Different Types ◽  
Simulation Results ◽  
Materials Used

Abstract This paper discusses the damping capabilities of polymer materials with mechanical characteristics which vary through the thickness. The case studied is that of a beam coated with a single layer of this material, which can be classified as a free layer damping coating. A simple mechanical model of the system is proposed, together with a suitable modelling of the gradient material. Simulation results based on realistic cases are presented for different types of distribution through the thickness and their damping performance is assessed.

Comparison of Ball Bearing Model Performance With and Without Centrifugal and Gyroscopic Forces

2014 ◽  
Author(s):  
Emil Kurvinen ◽  
Jussi Sopanen ◽  
Aki Mikkola
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Ball Bearing ◽  
Model Performance ◽  
Significant Loss ◽  
The Other ◽  
Model Complexity ◽  
Centrifugal Forces ◽  
Gyroscopic Forces ◽  
Simulation Results

Bearing performance significantly affects the dynamic behaviors and estimated working life of a rotating system. A common bearing type is the ball bearing, which has been under investigation in numerous published studies. The complexity of the ball bearing models described in the literature varies as models with or without the inclusion of centrifugal forces or the gyroscopic moments of the rolling elements are equally proposed. Naturally, model complexity is related to computational burden. In particular, the inclusion of centrifugal forces and gyroscopic moments significantly increases the system degrees of freedom and lengthens solution time. On the other hand, for low or moderate rotating speeds, these effects can be neglected without significant loss of accuracy. The objective of this paper is to present guidelines for the appropriate selection of a suitable bearing model for a case study. To this end, two ball bearing models were implemented. One considers high-speed forces, and the other neglects them. Both models were used to study a single structure, and the simulation results were compared. The bearing behavior is studied at different shaft rotation speeds and the simulation results are used to determine when the model containing the centrifugal and gyroscopic forces should be used.

Numerical Simulation and Experimental Research on Pedestal Looseness of a Rotor System

2007 ◽  
Author(s):  
Hui Ma ◽  
Hong Liang Yao ◽  
Zhao Hui Ren ◽  
Feng Wen ◽  
Bang Chun Wen
Keyword(s):  
Numerical Simulation ◽  
Mechanical Model ◽  
Test Rig ◽  
Rotating Speed ◽  
Runge Kutta Method ◽  
Motion State ◽  
Simulation And Experiment ◽  
State Changes ◽  
Simulation Results ◽  
Set Up

The mechanical model of looseness of fastening bolt on the bearing pedestal is set up based on the project practice. Using the nonlinear oil-film model put forward by Adiletta, the dynamic characteristics were investigated by numerical Runge-Kutta method. At last, the experiment is performed to investigate the pedestal looseness by a test rig and the fault signals are analyzed by the spectrum cascade and reassigned wavelet scalogram. Numerical simulation and experiment all show that system motion state changes frequently with the increase of the rotating speed. And the experimental results coincide with the simulation results.

scholarly journals Macro Modeling of V-Shaped Electro-Thermal MEMS Actuator with Human Error Factor

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 622
Author(s):  
Dongpeng Zhang ◽  
Anjiang Cai ◽  
Yulong Zhao ◽  
Tengjiang Hu
Keyword(s):  
Neural Network ◽  
Simulation Model ◽  
Bp Neural Network ◽  
Human Error ◽  
Calculation Model ◽  
Fuzzy Mathematics ◽  
Ansys Simulation ◽  
Macro Modeling ◽  
Error Factor ◽  
Simulation Results

The V-shaped electro-thermal MEMS actuator model, with the human error factor taken into account, is presented in this paper through the cascading ANSYS simulation model and the Fuzzy mathematics calculation model. The Fuzzy mathematics calculation model introduces the human error factor into the MEMS actuator model by using the BP neural network, which effectively reduces the error between ANSYS simulation results and experimental results to less than 1%. Meanwhile, the V-shaped electro-thermal MEMS actuator model, with the human error factor included, will become more accurate as the database of the V-shaped electro-thermal actuator model grows.

Crack Resistance Function Analysis of Flexible Short Fiber in Asphalt

2011 ◽  
Vol 243-249 ◽  
pp. 4182-4187
Author(s):  
Zhi Yong Ding ◽  
Jing Liang Dai ◽  
Bo Peng
Keyword(s):  
Mechanical Model ◽  
Function Analysis ◽  
Short Fiber ◽  
Calculation Model ◽  
Tensile Failure ◽  
Spherical Coordinates ◽  
Short Fibers ◽  
Flexible Fiber ◽  
Fiber Bridging ◽  
Resistance Function

after reasonably analyzing characteristics of flexible fiber reinforcement fragile material, the mechanical model of individual fiber is established while being pulled out from asphalt; the spherical coordinates is adopted to establish the calculation model for short fiber bridging stress evenly distributed in space to calculate the value of bridging stress generated by short fibers while asphalt is breaking; the fiber asphalt sample in big size is adopted to perform low temperature tensile failure test to practically measure bridging stress of short fiber; fit the calculated value and measured value of bridging stress by adjusting parameters in the calculation model to check the rationality of fiber bridging stress in calculation method and model.

Numerical Investigation for Characteristics and Oil-Air Distributions of a Tilting-Pad Journal Bearing Under Different Loads

2020 ◽  
Author(s):  
Aoshuang Ding ◽  
Xuesong Li
Keyword(s):  
Film Thickness ◽  
Journal Bearing ◽  
Viscosity Ratio ◽  
Cavitation Model ◽  
Tilting Pad ◽  
Sst Model ◽  
Bearing Load ◽  
Simulation Results ◽  
Bearing Loads ◽  
Tilting Pad Journal Bearing

Abstract This paper analyses the flow characteristics and oil-air distributions of oil flows in a tilting-pad journal bearing under different bearing loads. This titling-pad journal bearing is working at 3000 rpm rotation speed and its minimum film thicknesses have been measured under different loads from 180 kN to 299 kN. Based on the previous researches of this bearing under 180 kN, the gaseous cavitation and low-turbulence flow exists in this bearing flow. A suitable gaseous cavitation model and the SST model with low-Re correction are used in the film flow simulations. With the rotor and pads assumed to be rigid, the dynamic mesh and motion equations are applied to simulate the motions of the rotor and the rotations of the pads. Based on the simulation results under different bearing loads, the simulated minimum film thicknesses agrees well with the measured data. It indicates that the simulation results can catch the film geometries and flows correctly. With the load increasing, the rotor moves closer to the loaded pads and the minimum film thickness decreases. Taking the effect of boundary layers into consideration, the turbulence has a negative relationship with the film thickness and decreases in the loaded area under higher bearing load. It can be verified by the simulated lower turbulent viscosity ratio distributions in the loaded pads. In the unloaded area, both the film thickness and turbulence viscosity ratio are positively related to the bearing loads. Thus, the higher bearing load may lead the flow to be more different in the loaded and unloaded area, and the turbulence in the loaded pads may transfer to laminar in the end. As for the oil-air distributions, in the unloaded pads, with the bearing load increasing, the simulated air volume fraction increases in the unloaded pads with lower pressure. It should be caused by the higher film thickness of the unloaded pads under higher loads. In sum, the flow turbulence and cavitation process changes with the bearing load. With a higher load, the cavitation becomes more in the unloaded pads and the flow changes sharper from the high-turbulence unloaded area to the low-turbulence loaded area. As the simulation results is in good accordance with the experimental data, the SST model with low-Re correction and the gaseous cavitation model are verified to be suitable for bearing film simulations under different loads.

Investigation of Point Load Index Using Novel Discrete Based Model

2016 ◽  
Vol 846 ◽  
pp. 348-353
Author(s):  
Somayeh Behraftar ◽  
Joshua Heslin ◽  
S. Galindo Torres ◽  
Alexander Scheuermann
Keyword(s):  
Compressive Strength ◽  
Material Properties ◽  
Mechanical Model ◽  
Rock Type ◽  
Correlation Factor ◽  
Point Load ◽  
Load Test ◽  
Point Load Index ◽  
Bonded Particles ◽  
The One

In this study, a micro-mechanical model is developed to study the correlation of the point load index in rocks with uniaxial compressive strength (UCS) tests. The model is represented by an array of bonded particles simulated by a novel discrete based model, which was introduced by the authors previously. The point load test (PLT) is performed in the field on rock samples to classify and estimate the UCS of a rock type via the index-to-strength correlation factor k. Numerical analyses, such as the one presented in this work, will serve to close the knowledge gap concerning the correlation between k, UCS and other material properties of rocks.

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