Design of Four Contact-Point Slewing Bearing With a New Load Distribution Procedure to Account for Structural Stiffness

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Mireia Olave ◽  
Xabier Sagartzazu ◽  
Jorge Damian ◽  
Alberto Serna
Keyword(s):  
Load Distribution ◽  
Contact Point ◽  
Element Model ◽  
Contact Forces ◽  
Elastic Model ◽  
Slewing Bearing ◽  
Extreme Loads ◽  
Highly Nonlinear ◽  
Rolling Elements ◽  
Bearing Rings

This paper proposes a procedure for obtaining the load distribution in a four contact-point slewing bearing considering the effect of the structure’s elasticity. The uneven stiffness of the rings and the supporting structures creates a variation with respect to the results obtained with a rigid model. It is necessary to evaluate the effect of the elasticity on the increase in the contact forces in order to be able to design the slewing bearing and the structures involved in the connection. Depending on the shape of the structures, the contact force value obtained on the most loaded rolling element is different. The evaluation of this maximum force at extreme loads is essential to design the structures joined to the bearing rings. The new elastic model presented in this paper is highly nonlinear so iterative loops are needed in order to obtain a satisfactory solution. At the same time a finite element model (FEM) has been created for the global model, having also represented the rolling elements and their contact with the raceways. The results obtained using the FEM have been correlated with the results of the new procedure.

Modeling of Load Distribution in Large-Size Wind Turbine Blade Bearings

2011 ◽  
Vol 199-200 ◽  
pp. 1410-1413 ◽  
Author(s):  
Zhen Guo Shang ◽  
Tian Yi Gao ◽  
Hua Wang
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Load Distribution ◽  
Point Contact ◽  
Element Model ◽  
Wind Turbine Blade ◽  
Contact Forces ◽  
Large Size ◽  
Rolling Elements ◽  
Rigid Model

This paper proposes a procedure for obtaining the load distribution in a four point contact wind turbine blade bearing considering the effect of the structure’s elasticity. The uneven stiffness of the rings and the supporting structures creates a variation with respect to the results obtained with a rigid model. It is necessary to evaluate the effect of the elasticity on the increase in the contact forces in order to be able to design the wind turbine blade bearing and the structures involved in the connection. A finite element model (FEM) has been created for the global model, having also represented the rolling elements and their contact with the raceways. The results obtained using the FEM have been compared with the traditional Hertz contact results.

Finite Element Analysis of Large-Size Yaw Bearings with Supporting Structure in Wind Turbine

2014 ◽  
Vol 672-674 ◽  
pp. 1550-1553
Author(s):  
Zhen Guo Shang ◽  
Zhong Chao Ma ◽  
Zhen Sheng Sun
Keyword(s):  
Finite Element ◽  
Wind Turbine ◽  
Point Contact ◽  
Element Model ◽  
Contact Forces ◽  
Element Analysis ◽  
Supporting Structure ◽  
Rolling Elements ◽  
Yaw Bearing ◽  
Compression Springs

A procedure for obtaining the load distribution in a four point contact wind turbine yaw bearing considering the effect of the structure’s elasticity is presented. The inhomogeneous stiffness of the supporting structures creates a variation in the results obtained with a rigid model. A finite element model substituting the rolling elements with nonlinear compression springs has been built to evaluate the effect of the supporting structure elasticity on the contact forces between the rolling elements and the raceways.

Benchmark of a Novel Aero-Elastic Simulation Code for Small Scale VAWT Analysis

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
David Marten ◽  
Matthew Lennie ◽  
George Pechlivanoglou ◽  
Christian Oliver Paschereit ◽  
Alessandro Bianchini ◽  
...  
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Open Source ◽  
Structural Model ◽  
Element Model ◽  
Small Scale ◽  
Elastic Model ◽  
Element Analysis ◽  
Simulation Code ◽  
Highly Nonlinear

After almost 20 years of absence from research agendas, interest in the vertical axis wind turbine (VAWT) technology is presently increasing again, after the research stalled in the mid 90's in favor of horizontal axis wind turbines (HAWTs). However, due to the lack of research in past years, there are a significantly lower number of design and certification tools available, many of which are underdeveloped if compared to the corresponding tools for HAWTs. To partially fulfill this gap, a structural finite element analysis (FEA) model, based on the Open Source multiphysics library PROJECT::CHRONO, was recently integrated with the lifting line free vortex wake (LLFVW) method inside the Open Source wind turbine simulation code QBlade and validated against numerical and experimental data of the SANDIA 34 m rotor. In this work, some details about the newly implemented nonlinear structural model and its coupling to the aerodynamic solver are first given. Then, in a continuous effort to assess its accuracy, the code capabilities were here tested on a small-scale, fast-spinning (up to 450 rpm) VAWT. The study turbine is a helix shaped, 1 kW Darrieus turbine, for which other numerical analyses were available from a previous study, including the results coming from both a one-dimensional beam element model and a more sophisticated shell element model. The resulting data represented an excellent basis for comparison and validation of the new aero-elastic coupling in QBlade. Based on the structural and aerodynamic data of the study turbine, an aero-elastic model was then constructed. A purely aerodynamic comparison to experimental data and a blade element momentum (BEM) simulation represented the benchmark for QBlade aerodynamic performance. Then, a purely structural analysis was carried out and compared to the numerical results from the former. After the code validation, an aero-elastically coupled simulation of a rotor self-start has been performed to demonstrate the capabilities of the newly developed model to predict the highly nonlinear transient aerodynamic and structural rotor response.

Benchmark of a Novel Aero-Elastic Simulation Code for Small Scale VAWT Analysis

2018 ◽  
Author(s):  
David Marten ◽  
Matthew Lennie ◽  
George Pechlivanoglou ◽  
Christian Oliver Paschereit ◽  
Alessandro Bianchini ◽  
...  
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Open Source ◽  
Structural Model ◽  
Element Model ◽  
Small Scale ◽  
Elastic Model ◽  
Vertical Axis Wind Turbine ◽  
Simulation Code ◽  
Highly Nonlinear

After almost 20 years of absence from research agendas, interest in the vertical axis wind turbine (VAWT) technology is presently increasing again, after the research stalled in the mid 90’s in favour of horizontal axis turbines (HAWTs). However, due to the lack of research in past years, there are a significantly lower number of design and certification tools available, many of which are underdeveloped if compared to the corresponding tools for HAWTs. To partially fulfil this gap, a structural FEA model, based on the Open Source multi-physics library PROJECT::CHRONO, was recently integrated with the Lifting Line Free Vortex Wake method inside the Open Source wind turbine simulation code QBlade and validated against numerical and experimental data of the SANDIA 34m rotor. In this work some details about the newly implemented nonlinear structural model and its coupling to the aerodynamic solver are first given. Then, in a continuous effort to assess its accuracy, the code capabilities were here tested on a small scale, fast-spinning (up to 450 rpm) VAWT. The study turbine is a helix shaped, 1kW Darrieus turbine, for which other numerical analyses were available from a previous study, including the results coming from both a 1D beam element model and a more sophisticated shell element model. The resulting data represented an excellent basis for comparison and validation of the new aero-elastic coupling in QBlade. Based on the structural and aerodynamic data of the study turbine, an aero-elastic model was then constructed. A purely aerodynamic comparison to experimental data and a BEM simulation represented the benchmark for QBlade aerodynamic performance. Then, a purely structural analysis was carried out and compared to the numerical results from the former. After the code validation, an aero-elastically coupled simulation of a rotor self-start has been performed to demonstrate the capabilities of the newly developed model to predict the highly nonlinear transient aerodynamic and structural rotor response.

A Remote Solitary Wave–based Technique for Monitoring Corrosion in Steel Structures: Numerical Analysis and Experimental Validation

2021 ◽  
Author(s):  
Hoda Jalali ◽  
Piervincenzo Rizzo
Keyword(s):  
Solitary Wave ◽  
Solitary Waves ◽  
Plate Thickness ◽  
Point Contact ◽  
Element Model ◽  
Contact Forces ◽  
Localized Corrosion ◽  
Spherical Particles ◽  
Corrosion Monitoring ◽  
Highly Nonlinear

Abstract A new corrosion monitoring technique based on the generation and propagation of highly nonlinear solitary waves in 1D granular crystals has been developed recently. In this method, a monoperiodic array of spherical particles, interacting via Hertzian contact forces, is in point contact with the structure or material to be inspected. The array is part of a wireless unit used to induce the wave in the chain and record the solitary waveform remotely. Compared to classical NDE techniques used for thickness monitoring, the developed method is low cost, portable, and simple. This study presents a numerical and an experimental investigation of the sensitivity of solitary waves to localized corrosion. In the experimental study, a corroding steel plate was monitored using solitary waves to examine the effect of corrosion in the plate on the solitary waves interacting with the plate. Furthermore, a discrete element model was coupled with a finite element model to numerically predict the effect of localized corrosion on the delay and the amplitude of the reflected solitary waves formed at the chain-plate interface. The plate was studied in both pristine and corroded conditions. Furthermore, the study investigated customizing the granular chain design to achieve solitary wave-based sensors that can be used in high-temperature environments with maximum sensitivity to corrosion. The numerical results were in good agreement with experimental results and showed that the reflected solitary waves are affected by the presence and the propagation of corrosion in the plate. It was also shown that the sensitivity of the method increases for thinner plates or when the depth of corrosion exceeds half of the plate thickness.

Effects of Load Distribution on Life of Radial Roller Bearings

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Takafumi Nagatomo ◽  
Ken Takahashi ◽  
Yoshiaki Okamura ◽  
Takehiko Kigawa ◽  
Shoji Noguchi
Keyword(s):  
Load Distribution ◽  
Rolling Bearing ◽  
Outer Ring ◽  
Contact Conditions ◽  
Internal Load ◽  
Load Distributions ◽  
Bearing Life ◽  
Rolling Elements ◽  
Endurance Tests ◽  
Bearing Rings

An external load applied to a radial rolling bearing is distributed among the rolling elements. In many applications, the bearing internal load distribution may be altered by the elastic deformations of the bearing rings. This alteration can have an effect on bearing life. The objective of this study is to investigate the effect of load distribution on bearing life, both theoretically and experimentally, using several housing models which provide different contact conditions between the housing bore and the outer ring. This paper first presents a newly developed method of determining dynamic load distributions with an optical fiber strain sensor. The measurements of the load distribution for the housing models by using this method have shown that the contact condition between the housing bore and the outer ring affects the load distribution, and the effect of the load distribution on the bearing life has been confirmed by the theoretical calculation of the bearing life. Furthermore, endurance tests using dented bearings were performed to validate the effect of load distribution on bearing life. The results of the tests have substantiated that the bearing life is substantially affected by the load distribution; moreover, it has been shown that there is a linear relationship between the calculated lives and the experimental ones.

Pre-Optimization of Asymmetrical Underplatform Dampers

2016 ◽  
Author(s):  
Chiara Gastaldi ◽  
Muzio M. Gola
Keyword(s):  
Contact Surface ◽  
Contact Stiffness ◽  
Contact Point ◽  
A Priori ◽  
Element Model ◽  
Contact Forces ◽  
Friction Coefficients ◽  
Lift Off ◽  
Lower Limits ◽  
Underplatform Damper

The numerical coupled optimization of an underplatform damper is the exploration of its dynamics through a finite element model which includes both the damper and the blades. This is an effective approach if the initial damper mass and geometry have been previously selected in such a way that those parameter combinations leading to undesirable damper behavior (i.e. contact point lift-off, jamming, excessive contact forces) are ruled out a priori. This can be obtained through a pre-optimization where, after choosing the damper type the following main steps are followed: 1. ensure that damper jamming is avoided through an appropriate choice of platform angles, in function of the friction coefficients; 2. ensure that damper lift-off is avoided through an appropriate choice of the shape and position of the damper-platform flat contact surface and the position of the damper mass center; 3. set upper and lower limits to the value of damper-platform contact forces (as a multiple of the damper centrifugal force), the first being related to friction and wear problems, the second to the very existence of bilateral contacts; 4. check the model, and in particular the values of friction coefficients and contact stiffness, against experimental results. Once the above knowledge concerning the most desirable damper shape has been gathered an effective coupled-optimization can safely be performed. This is done by finding the most effective match between the damper size/mass and the bladed disk through a non-linear dynamic calculation (not examined in this paper). The outcome of both the pre-optimization and the coupled optimization are strongly dependent on the assumed values of friction coefficients, which depend on the contact surface type (then, different for the left and right side of the damper) and the contact pressure. The paper capitalizes on already developed tools, presented in previous ASME papers, such as the test rig developed by the AERMEC lab to draw the appropriate values of contact parameters, the numerical model representing the stand-alone dynamics of the damper between the platforms and the automatic random sampling tuning procedure. The purpose of the paper is to illustrate the procedure through the analysis of a family of rigid bar dampers with a curved-flat cross section.

Strength check of a three-row roller slewing bearing based on a mixed finite element model

2016 ◽  
Vol 231 (18) ◽  
pp. 3393-3400 ◽  
Author(s):  
Yunfeng Li ◽  
Di Jiang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Internal Stress ◽  
Contact Stress ◽  
Mixed Finite Element ◽  
Element Model ◽  
Structural Deformation ◽  
Engineering Practice ◽  
Slewing Bearing ◽  
Bearing Rings

For the two failure modes of a three-row roller slewing bearing, ring fracture and raceway spalling, a method for checking the strength of a slewing bearing through finite element analysis is proposed. This method calculates the internal stress distribution of the bearing rings by using the mixed finite element model with both solid elements and spring elements of the slewing bearing assembly and checks the bearing structural strength by using the maximum internal stress of the bearing rings. The method also calculates the contact stress between the roller and raceways by using the entity contact model between the roller and the raceways; the obtained maximum contact stress is used to check the contact strength of the slewing bearing. The proposed mixed finite element model considers the structural deformation of the bearing rings, and the calculated results can reflect the real situation more accurately than the traditional analytical model with the hypothesis of rigid ring. The proposed method also avoids the solution problem, which has large-scale calculation and difficulty of convergence of the entity finite element model of a slewing bearing, and the calculation efficiency is improved effectively. The calculated results by mixed finite element model are consistent with the failure mode of this type of slewing bearing in engineering practice.

The Direct Contact Problem in a Trochoidal-Type Machine

1993 ◽  
Author(s):  
John B. Shung ◽  
Gordon R. Pennock
Keyword(s):  
Direct Contact ◽  
Contact Point ◽  
Element Model ◽  
Contact Forces ◽  
Combined Model ◽  
Normal Contact ◽  
Contact Points ◽  
Satisfactory Method ◽  
Type Machine ◽  
Static Conditions

Abstract Reducing the contact forces in a trochoidal-type machine is important because the machine can not be adjusted for wear. The main difficulty in calculating the contact forces is to determine the forces that are transmitted through each contact point. Since there are many points of contact, at any instant, the problem is quasi-statically indeterminate and no satisfactory method of analysis is available in the current literature. The first part of this paper presents a simplified analytical model of a trochoidal-type machine when friction and deformation at the contact points are neglected. From this model, closed-form equations are derived for the normal contact forces. Then the second part of the paper presents a combined analytical and finite element model of the same machine. The analysis for the combined model includes the effects of friction and deformation at the contact points. The analysis for both models is for quasi-static conditions. The results from the two models are compared and important conclusions are drawn.

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