Mechanical analysis of spherical roller bearings due to surface waviness

2016 ◽  
Vol 232 (4) ◽  
pp. 639-656 ◽  
Author(s):  
Yu Xing ◽  
Hua Xu ◽  
Xuejing Liu ◽  
Hui Xi ◽  
Shibin Wang
Keyword(s):  
Contact Angle ◽  
Mechanical Analysis ◽  
The Self ◽  
Hertzian Contact ◽  
Radial Clearance ◽  
Surface Waviness ◽  
Characteristic Frequencies ◽  
Roller Bearings ◽  
Runge Kutta Method ◽  
Proposed Model

This work presents a theoretical model to research the vibration due to surface waviness of spherical roller bearings (SRBs), taking account of the self-aligning feature and the external axial load. The surface waviness is described by cosinoidal functions. The self-aligning features, including the variation law of the self-aligning contact angle and the interaction with the external loads, are introduced into the non-Hertzian contact model. The nonlinear equations are solved by Runge–Kutta method and the proposed model is validated by comparing with the results of the published references. The results show more characteristic frequencies will be excited under the self-aligning operating condition, whereby the improved equations proposed in this paper are recommended to instead of the previous ones to predict characteristic frequencies of the waviness vibration in an SRB. In addition, these characteristic vibrations caused by waviness are obviously influenced by the magnitude and the direction of the self-aligning contact angle. A proper pretightening load should be chosen according to the self-aligning feature or else it will lead to hidden dangers. The radial clearance and the waviness amplitude can both highlight the effect of waviness. And the vibration caused by a larger radial clearance may be fiercer than the vibration due to waviness.

Dynamic Model of Spherical Roller Bearing

2013 ◽  
Author(s):  
Behnam Ghalamchi ◽  
Jussi T. Sopanen ◽  
Aki M. Mikkola
Keyword(s):  
Load Capacity ◽  
Roller Bearing ◽  
Industrial Applications ◽  
Hertzian Contact ◽  
Design Parameters ◽  
Steel Rolling ◽  
Roller Bearings ◽  
Proposed Model ◽  
Rotor Bearing ◽  
Transient Simulations

Rolling element bearings are essential machine elements in the rotating machinery. Extensive research has been conducted to study the dynamics of ball bearings, while studies related to spherical roller bearings are short-shrifted. On the other hand, the number of industrial applications that utilize spherical roller bearings has been increasing constantly. This is due to self-aligning nature and high-load capacity of spherical roller bearings. Typical applications are paper machines, steel rolling, marine equipment, geared transmissions and modern high power wind turbines. This study introduces a three-degree-of-freedom spherical roller bearing model that is computationally efficient, and it is designed to be used in the transient simulations of complete rotor-bearing systems. In the proposed model, the bearing forces are calculated as a function of contact deformation and bearing geometry parameters according to the non-linear Hertzian contact theory. In the numerical results, the important bearing design parameters such as diametral clearance, number of rollers and osculation are studied. Existence of varying compliance (VC) vibrations and the capability of the proposed model in the transient simulations of rotor-bearing systems are demonstrated. The bearing model is verified by using commercial bearing analysis software. Future improvements and model extension possibilities are also discussed.

A New Method to Model Spherical Roller Bearings due to Self-Aligning Feature

2015 ◽  
Author(s):  
Yu Xing ◽  
Hua Xu ◽  
Shiyuan Pei ◽  
Xuejing Liu ◽  
Fengcai Wang
Keyword(s):  
Contact Region ◽  
Linear Equations ◽  
Least Square Method ◽  
Least Square ◽  
Hertzian Contact ◽  
Design Parameters ◽  
Roller Bearings ◽  
Proposed Model ◽  
Computing Procedure ◽  
Maximum Contact

This research presents an analytical model to describe the indeterminate contact status and analyze the loaded condition, then acquire the key design parameters so as to improve the carrying capacity of spherical roller bearings. The model based on the non-Hertzian contact theory is applied to reflect the indeterminate contact status due to the self-aligning feature. The loaded condition, which is including the load distribution, the size of the contact region and the maximum contact pressure, is calculated according to the force analysis of spherical roller bearings. The non-linear equations are solved by using secant method and the proposed model is validated by comparing with the published reference. The importance of the indeterminate contact status is illustrated by comparing with the computing results of the Hertzian contact model. The fitted method based on the least square method is used to obtain the equivalent stiffness and the load-deformation exponent, whereby the computing procedure is simplified. In view of the operating condition and the lubricated effect, properly increasing the osculation number or the number of the rollers will obviously improve the carrying ability of spherical roller bearings.

scholarly journals Self-Cleaning Polyester Fabric Prepared with TiOF2 and Hexadecyltrimethoxysilane

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 387
Author(s):  
Euigyung Jeong ◽  
Heeju Woo ◽  
Yejin Moon ◽  
Dong Yun Lee ◽  
Minjung Jung ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Contact Angle ◽  
Treatment Method ◽  
Polyester Fabric ◽  
Anatase Tio2 ◽  
The Self ◽  
Water Contact ◽  
Direct Fluorination ◽  
Tomato Ketchup ◽  
Self Cleaning

In this study, self-cleaning polyester (PET) fabrics were prepared using TiOF2 and hexadecyltrimethoxysilane(HDS) treatment. TiOF2 was synthesized via direct fluorination of a precursor TiO2 at various reaction temperatures. The prepared PET fabrics had superior photocatalytic self-cleaning properties compared with anatase TiO2/HDS-treated PET fabrics under UV and sunlight with 98% decomposition of methylene blue. TiOF2/HDS-treated PET fabrics also had superior superhydrophobic self-cleaning properties compared with anatase TiO2/HDS-treated PET fabrics with a 161° water contact angle and 6° roll-off angle. After the self-cleaning tests of the non-dyed TiOF2/HDS-treated PET fabrics, we prepared dyed TiOF2/HDS-treated PET fabrics to test practical aspects of the treatment method. These PET fabrics were barely stained by tomato ketchup; even when stained, they could be self-cleaned within 4 h. These results suggest that practical self-cleaning PET fabrics with superhydrophobicity and photocatalytic degradation could be prepared using TiOF2/HDS-treatment.

Thermomechanical Model of Spot Welding for Calculating Residual Stresses

2003 ◽  
Author(s):  
Lijun Xu ◽  
Jamil A. Khan
Keyword(s):  
Residual Stresses ◽  
Heat Generation ◽  
Spot Welding ◽  
Welding Process ◽  
Mechanical Analysis ◽  
Temperature Dependent ◽  
Thermomechanical Model ◽  
Faying Surface ◽  
Proposed Model ◽  
Electrode Interface

A comprehensive axisymmetric model of the coupled thermal-electrical-mechanical analysis predicting weld nugget development and residual stresses for the resistance spot welding process of Al-alloys is developed. The model estimates the heat generation at the faying surface, the workpiece-electrode interface, and the Joule heating of the workpiece and electrode. The phase change due to melting in the weld pool is considered. The contact area and its pressure distribution at both the faying surface and the electrode-workpiece interface are determined from a coupled thermal-mechanical model using a finite element method. The knowledge of the interface pressure provides accurate prediction of the interfacial heat generation. For the numerical model, temperature dependent thermal, electrical and mechanical properties are used. The proposed model can successfidly calculate the nugget diameter and thickness, and predict the residual stresses and the elastic-plastic deformation history. The calculated nugget shape and the deformation of sheets based on the model are compared with the experimental data. The computed residual stresses approach the distribution of experimental measurement of the residual stress.

Vibration-Induced Loosening Performance of Preloaded Threaded Fasteners

2010 ◽  
Author(s):  
Xianjie Yang ◽  
Sayed Nassar
Keyword(s):  
Nonlinear Model ◽  
Excitation Amplitude ◽  
The Self ◽  
Transverse Displacement ◽  
Transverse Loading ◽  
Threaded Fasteners ◽  
Bolt Preload ◽  
Proposed Model ◽  
Number Of Cycles ◽  
Insight Into

In an effort to establish a theoretical outline of a criterion for preventing the vibration-induced loosening of preloaded threaded fasteners, this paper provides an experimental and analytical insight into the effect of the initial bolt preload and the excitation amplitude on the self loosening performance of cap screw fastener. A nonlinear model is used for predicting the clamp load loss caused by the vibration-induced loosening of cap screw fasteners under cyclic transverse loading. Experimental verification was conducted on the twisting torque variation and the effect of the preload level and transverse displacement amplitude. Comparison of the experimental and analytical results on the clamp load loss with the number of cycles verifies that the proposed model accurately predicts self-loosening performance.

Theoretical Tire Model Considering Two-Dimensional Contact Patch for Force and Moment

2021 ◽  
Author(s):  
Y. Nakajima ◽  
S. Hidano
Keyword(s):  
Finite Element Method ◽  
Shear Force ◽  
The Self ◽  
Slip Angle ◽  
Force Distribution ◽  
Two Dimensional ◽  
Tire Model ◽  
Side Force ◽  
Contact Patch ◽  
Proposed Model

ABSTRACT The new theoretical tire model for force and moment has been developed by considering a two-dimensional contact patch of a tire with rib pattern. The force and moment are compared with the calculation by finite element method (FEM). The side force predicted by the theoretical tire model is somewhat undervalued as compared with the FEM calculation, while the self-aligning torque predicted by the theoretical tire model agrees well with the FEM calculation. The shear force distribution in a two-dimensional contact patch under slip angle predicted by the proposed model qualitatively agrees with the FEM calculation. Furthermore, the distribution of the adhesion region and sliding region in a two-dimensional contact patch predicted by the theoretical tire model qualitatively agrees with the FEM calculation.

scholarly journals Duration Perception Versus Perception Duration: A Proposed Model for the Consciously Experienced Moment

2019 ◽  
Vol 7 (1) ◽  
pp. 1-14 ◽  
Author(s):  
Lachlan Kent
Keyword(s):  
Information Theory ◽  
Prediction Error ◽  
Intermediate Stage ◽  
The Self ◽  
Global Integration ◽  
Candidate Model ◽  
Time Space ◽  
Proposed Model ◽  
Concrete Objects ◽  
Integrated Information Theory

Duration perception is not the same as perception duration. Time is an object of perception in its own right and is qualitatively different to exteroceptive or interoceptive perception of concrete objects or sensations originating within the self. In reviewing evidence for and against the experienced moment, White (2017, Psychol. Bull., 143, 735–756) proposed a model of global integration of information dense envelopes of integration. This is a valuable addition to the literature because it supposes that, like Tononi’s (2004, BMC Neurosci., 5, 42) Integrated Information Theory, consciousness is an integral step above perception of objects or the self. Consciousness includes the perception of abstract contents such as time, space, and magnitude, as well as post-perceptual contents drawn from memory. The present review takes this logic a step further and sketches a potential neurobiological pathway through the salience, default mode, and central executive networks that culminates in a candidate model of how duration perception and consciousness arises. Global integration is viewed as a process of Bayesian Prediction Error Minimisation according to a model put forward by Hohwy, Paton and Palmer (2016, Phenomenol. Cogn. Sci., 15, 315–335) called ‘distrusting the present’. The proposed model also expresses global integration as an intermediate stage between perception and memory that spans an approximate one second duration, an analogue of Wittmann’s (2011, Front. Integr. Neurosci., 5, 66) experienced moment.

scholarly journals Influence of radial clearance on nonlinear dynamics of a two-span three-support rotor system

2021 ◽  
Vol 233 ◽  
pp. 04012
Author(s):  
HE Xing ◽  
WU Yi-ming ◽  
LI Mo ◽  
ZENG Fan
Keyword(s):  
Periodic Motion ◽  
Rotor System ◽  
System Model ◽  
Radial Clearance ◽  
Structural Form ◽  
Single Cycle ◽  
Rolling Bearings ◽  
System A ◽  
Runge Kutta Method ◽  
Nonlinear Dynamic Characteristics

Aiming at the structural form of a certain rotor system, a double-span three-support rotor system model is established. It is supported by three rolling bearings and has a typical nonlinear characteristic. The fourth-order Runge-Kutta method is used to solve the differential equations and analyze the nonlinear dynamic characteristics of the rotor system when the radial clearance of the bearing changed. The research results: with the increase of the rear bearing radial clearance, the rotor system performs single cycle, periodic two and pseudo-periodic motion. With the three location bearing radial clearance increases, the rotor system performs single cycle, periodic two and periodic four motion. When the radial clearance is bigger, the rotor system performs two periodic motion. The influence law of radial clearance on double span three - braced rotor system is shown.

scholarly journals Let Them Learn

2021 ◽  
Vol 7 (2) ◽  
pp. 230-260
Author(s):  
Christian Martinez
Keyword(s):  
Critical Analysis ◽  
Oil And Gas ◽  
Common Law ◽  
Case Law ◽  
The Self ◽  
Self Assessment ◽  
Proposed Model ◽  
Design Build ◽  
Free Flow Of Information ◽  
Flow Of Information

Organizations often conduct probing self-studies to review internally existing policies, procedures, and business methods. Yet, despite an increasing social need for these studies, the Texas legislature has yet to construct a privilege designed to protect an organization from being harmed from these studies by adverse litigants. The self-critical analysis privilege, or SCAP, is an alluring, common law doctrine that protects the free flow of information sharing through an organization’s self-assessment. This Comment proposes a model statute for the codification of the SCAP for the consideration of the Texas legislature. This model statute is not a general codification of the privilege. Instead, the statute is meant to apply only to Texas’s Design-Build industry. This Comment discusses the significant policy considerations supporting the SCAP and analyzes case law to derive proper drafting language. Although this proposed model statute narrowly applies to Texas’s Design-Build industry, the hope is to have a workable statute that could apply to general products, oil and gas, and other property related industries.

scholarly journals Modeling and Dynamic Analysis of Spherical Roller Bearing with Localized Defects: Analytical Formulation to Calculate Defect Depth and Stiffness

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Behnam Ghalamchi ◽  
Jussi Sopanen ◽  
Aki Mikkola
Keyword(s):  
Dynamic Model ◽  
Contact Stiffness ◽  
Roller Bearing ◽  
Measurement Data ◽  
Contact Forces ◽  
Hertzian Contact ◽  
Radial Clearance ◽  
Outer Race ◽  
Rolling Elements ◽  
Localized Defects

Since spherical roller bearings can carry high load in both axial and radial direction, they are increasingly used in industrial machineries and it is becoming important to understand the dynamic behavior of SRBs, especially when they are affected by internal imperfections. This paper introduces a dynamic model for an SRB that includes an inner and outer race surface defect. The proposed model shows the behavior of the bearing as a function of defect location and size. The new dynamic model describes the contact forces between bearing rolling elements and race surfaces as nonlinear Hertzian contact deformations, taking radial clearance into account. Two defect cases were simulated: an elliptical surface on the inner and outer races. In elliptical surface concavity, it is assumed that roller-to-race-surface contact is continuous as each roller passes over the defect. Contact stiffness in the defect area varies as a function of the defect contact geometry. Compared to measurement data, the results obtained using the simulation are highly accurate.

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