A New Approach for Including Cage Flexibility in Dynamic Bearing Models by Using Combined Explicit Finite and Discrete Element Methods

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Ankur Ashtekar ◽  
Farshid Sadeghi
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Experimental Studies ◽  
Discrete Element ◽  
Operating Conditions ◽  
Contact Forces ◽  
Time Step ◽  
New Approach ◽  
Explicit Finite Element ◽  
Shaft Misalignment

In this investigation, a new approach was developed to study the influence of cage flexibility on the dynamics of inner and outer races and balls in a bearing. A 3D explicit finite element model (EFEM) of the cage was developed and combined with an existing discrete element dynamic bearing model (DBM) with six degrees of freedom. The EFEM was used to determine the cage dynamics, deformation, and resulting stresses in a ball bearing under various operating conditions. A novel algorithm was developed to determine the contact forces between the rigid balls and the flexible (deformable) cage. In this new flexible cage dynamic bearing model, the discrete and finite element models interact at each time step to determine the position, velocity, acceleration, and forces of all bearing components. The combined model was applied to investigate the influence of cage flexibility on ball-cage interactions and the resulting ball motion, cage whirl, and the effects of shaft misalignment. The model demonstrates that cage flexibility (deflection) has a significant influence on the ball-cage interaction. The results from this investigation demonstrate that the magnitude of ball-cage impacts and the ball sliding reduced in the presence of a flexible cage; however, as expected, the cage overall motion and angular velocity were largely unaffected by the cage flexibility. During high-speed operation, centrifugal forces contribute substantially to the total cage deformation and resulting stresses. When shaft misalignment is considered, stress cycles are experienced in the bridge and rail sections of the cage where fatigue failures have been observed in practice and in experimental studies.

Investigation of Turbocharger Dynamics Using a Combined Explicit Finite and Discrete Element Method Rotor–Cartridge Model

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Matthew D. Brouwer ◽  
Farshid Sadeghi
Keyword(s):  
Finite Element ◽  
Discrete Element Method ◽  
Ball Bearing ◽  
Discrete Element ◽  
Operating Conditions ◽  
Test Rig ◽  
Explicit Finite Element ◽  
Critical Speeds ◽  
Bearing Dynamics ◽  
Element Method

The objectives of this investigation were to develop a coupled dynamic model for turbocharger ball bearing rotor systems, correlate the simulated shaft motion with experimental results, and analyze the corresponding bearing dynamics. A high-speed turbocharger test rig was designed and developed in order to measure the dynamic response of a rotor under various operating conditions. Displacement sensors were used to record shaft motion over a range of operating speeds. To achieve the objectives of the analytical investigation, a discrete element angular contact ball bearing cartridge model was coupled with an explicit finite element shaft to simulate the dynamics of the turbocharger test rig. The bearing cartridge consists of a common outer ring, a pair of split inner races, and a row of balls on each end of the cartridge. The dynamic cartridge model utilizes the discrete element method in which each of the bearing components (i.e., races, balls, and cages) has six degrees-of-freedom. The rotor is modeled using the explicit finite element method. The cartridge and rotor models are coupled such that the motion of the flexible rotor is transmitted to the inner races of the cartridge with the corresponding reaction forces and moments from the bearings being applied to the rotor. The coupled rotor–cartridge model was used to investigate the shaft motion and bearing dynamics as the system traverses critical speeds. A comparison of the analytical and experimental shaft motion results resulted in minimal correlation but showed similarity through the critical speeds. The cartridge model allowed for thorough investigation of bearing component dynamics. Effects of ball material properties were found to have a significant impact on turbocharger rotor and bearing dynamics.

scholarly journals Effect of wheel–rail interface parameters on contact stability in explicit finite element analysis

2018 ◽  
Vol 232 (6) ◽  
pp. 1879-1894 ◽  
Author(s):  
Yuewei Ma ◽  
Valeri L Markine ◽  
Abdul Ahad Mashal ◽  
Mingfa Ren
Keyword(s):  
Finite Element ◽  
Contact Stiffness ◽  
Normal Pressure ◽  
Accurate Solution ◽  
Contact Forces ◽  
Time Step ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Contact Stability ◽  
Interface Parameters

It is widely recognized that the accuracy of explicit finite element simulations is sensitive to the choice of interface parameters (i.e. contact stiffness/damping, mesh generation, etc.) and time step sizes. Yet, the effect of these interface parameters on the explicit finite element based solutions of wheel–rail interaction has not been discussed sufficiently in literature. In this paper, the relation between interface parameters and the accuracy of contact solutions is studied. It shows that the wrong choice of these parameters, such as too high/low contact stiffness, coarse mesh, or wrong combination of them, can negatively affect the solution of wheel–rail interactions which manifest in the amplification of contact forces and/or inaccurate contact responses (here called “contact instability”). The phenomena of “contact (in)stabilities” are studied using an explicit finite element model of a wheel rolling over a rail. The accuracy of contact solutions is assessed by analyzing the area of contact patches and the distribution of normal pressure. Also, the guidelines for selections of optimum interface parameters, which guarantee the contact stability and therefore provide an accurate solution, are proposed. The effectiveness of the selected interface parameters is demonstrated through a series of simulations. The results of these simulations are presented and discussed.

Explicit Finite Element Simulation of Granular Flow in an Annular Shear Cell

2009 ◽  
Author(s):  
M. A. Kabir ◽  
C. F. Higgs ◽  
M. R. Lovell ◽  
V. Jasti ◽  
M. C. Marinack
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Granular Flow ◽  
High Speed ◽  
Flow Behavior ◽  
Shear Cell ◽  
Explicit Finite Element Method ◽  
Explicit Finite Element ◽  
Annular Shear Cell ◽  
Element Method

Explicit finite element method modeling of granular flow behavior in an annular shear cell has been studied and presented in this paper. The explicit finite element method (FEM) simulations of granular flow in an annular shear cell with around 1633 particles were performed, where the inner wheel rotated at a very high speed and the outer disk remained stationary. The material properties of the particles and the outer wheel were defined as elastic steel whereas the inner wheel was elastic aluminum. In this investigation, the explicit FEM model mimicked granular flow in an experimental set up where the inner wheel was rotated at a speed of 240 rpm. The FEM results for shearing motion and solid fraction were compared with experimental results from a granular shear cell.

Requirements for Numerical Flange Calculations According to the German Nuclear Code

2002 ◽  
Author(s):  
Robert Kauer
Keyword(s):  
Finite Element ◽  
Operating Conditions ◽  
Metal Contact ◽  
Finite Element Analyses ◽  
Rate Dependency ◽  
New Approach ◽  
Contact Type ◽  
Numerical Finite Element ◽  
Floating Type ◽  
Code Compliance

In Europe as well as in other countries a lot of effort is invested into developing new codes and standards for bolted joints under various loading conditions. The standardization of gasket factors and the improvement of calculation methods with respect to these factors characterize the last couple of years in this area. In Germany the nuclear code (KTA) is also influenced by this development. So, the leak rate dependency of gasket factors and the results of a research program on metal-to-metal contact type flanges were introduced into the new approach of the code for Class 2 and 3 components. Herein flange calculations can be performed for various flange types, floating type and metal-to-metal contact type. Generally, the calculations to be performed can be separated into a design step and the proof of sufficient tightness and strength of flange, bolts and gasket for the various operating conditions according to the chosen bolting method. In this step the stiffness of all components (flanges, bolts and gasket) and its influence on the mechanical behavior of the entire system is considered. Besides, influences caused by thermal effects, e.g. different thermal expansion between the flanges and the bolts, or seating effects in the gasket must be regarded. In cases, where the allowable stress values are not satisfied by performing code calculations or in cases, where the applicability of the code is not given, e.g. due to geometric facts, Finite-Element analyses often replace code calculations to show code compliance. Therefore, numerical Finite-Element analyses, performed according to a special code, e.g. KTA, must also fulfill the requirements of the code with respect to considered load cases, bolting condition, allowable stresses etc., to get an adequate testimony for a certain flange joint. In this paper certain methods for numerical calculations will be presented and compared to the results of the code for various flange types and dimensions.

An Experimental and Numerical Study to Analysis and Design of Sheet Hydroforming Process for an Automobile Fender Shell

2006 ◽  
Author(s):  
Mohammad Habibi Parsa ◽  
Payam Darbandi
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Fluid Pressure ◽  
Finite Element Program ◽  
New Approach ◽  
Explicit Finite Element ◽  
Sheet Hydroforming ◽  
Analysis And Design ◽  
Hydroforming Process ◽  
Element Program

A new approach for manufacturing of shell fender is proposed and has been examined numerically and experimentally. The new suggested method is based on sheet hydroforming process, which has a lot of advantages over conventional deep drawing process. After defining the shape of initial blank using an inverse finite element program, numerical evaluation of the proposed sheet hydroforming process for production of shell fender has been carried out using an explicit finite element code considering fluid pressure, boundary conditions and tools. Then experimental evaluation has been carried out using down sized specimen and the results have been compared with results of previous simulations. It has been shown that there are similar trends between finite element and experimental results.

Fatigue Finite Element Analysis of Certain Type of EMU Gearbox Box

2015 ◽  
Vol 789-790 ◽  
pp. 236-240
Author(s):  
Jiao Zhang ◽  
Xi Li ◽  
Hao Xie
Keyword(s):  
Finite Element ◽  
Fatigue Failure ◽  
High Speed ◽  
Peak Load ◽  
Load Cycle ◽  
Fatigue Analysis ◽  
Operating Conditions ◽  
Element Analysis ◽  
Static Fracture ◽  
Strength And Stiffness

EMU gearbox is a key component of high-speed train, the reliability of the gearbox will directly affect the operational safety of EMU. The box of EMU gearbox is with light alloy materials, bearing structure, so the box is subjected to greater loads and shock and vibration. Designers most take into account the static strength and stiffness of the box, ignore the fatigue failure. Fatigue failure is the leading cause of mechanical structural failure, while the peak load cycle fatigue failure is often far less than estimated in accordance with the static fracture analysis "safe" load, so the EMU gearbox box’s fatigue analysis is needed. Combining high-speed EMU gearbox actual operating conditions, using finite element method to do fatigue analysis of the gearbox box while the analysis result is evaluated and amended by the Smith schematic analysis method.

Implicit-Explicit Finite Elements in Transient Analysis: Stability Theory

1978 ◽  
Vol 45 (2) ◽  
pp. 371-374 ◽  
Author(s):  
T. J. R. Hughes ◽  
W. K. Liu
Keyword(s):  
Finite Element ◽  
Finite Elements ◽  
Transient Analysis ◽  
Critical Time ◽  
Unconditional Stability ◽  
Time Step ◽  
Explicit Finite Element ◽  
New Family ◽  
Critical Time Step ◽  
Analysis Stability

A stability analysis is carried out for a new family of implicit-explicit finite-element algorithms. The analysis shows that unconditional stability may be achieved for the implicit finite elements and that the critical time step of the explicit elements governs for the system.

An analytical contact model for finite element analysis of tube spinning process

2008 ◽  
Vol 222 (11) ◽  
pp. 1375-1385 ◽  
Author(s):  
H Lexian ◽  
B M Dariani
Keyword(s):  
Finite Element ◽  
Pressure Vessel ◽  
Shell Element ◽  
Fe Analysis ◽  
Contact Forces ◽  
Contact Model ◽  
Integration Scheme ◽  
Time Step ◽  
Tube Spinning ◽  
Spinning Process

This work presents an analytical contact model for non-linear dynamic finite element (FE) analysis of the tube spinning process that is based on the Belytschko—Lin—Tsay shell element with an explicit time integration scheme. A brief description of the FE formulation of a first-order shear deformation shell element as well as internal forces calculation, nodal mass calculation, and prediction of stable time step are presented. An analytical contact model is developed for a general roller. Analytical equations of the roller surfaces, interpenetration, and unit vector normal to the contact surface are determined. Contact forces are approximated by a penalty method with a suitable estimation of the penalty coefficient. An explicit FE code, using the developed analytical contact model, is designed and its implementation algorithm is described in detail. The dome forming process of a seamless pressure vessel is simulated using this code, in which the contact analysis is performed robustly, which saves significant amounts of computer time. A steel alloy DIN 1.7225 seamless pressure vessel, which was formed by a hot-spinning process, is cut longitudinally and its profile is measured. A comparison between the longitudinal cross-section profiles calculated by FE analysis and that obtained from experiment shows a good agreement.

Lubrication and Thermal Failure Mechanism Analysis in High-Speed Angular Contact Ball Bearing

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Wang Yunlong ◽  
Wang Wenzhong ◽  
Li Yulong ◽  
Zhao Ziqiang
Keyword(s):  
Rotational Speed ◽  
High Speed ◽  
Ball Bearing ◽  
Rolling Bearing ◽  
Operating Conditions ◽  
Contact Forces ◽  
Mechanism Analysis ◽  
Angular Contact Ball Bearing ◽  
Thermal Failure ◽  
Lubrication Performance

Lubrication analysis of rolling bearing is often conducted with assumed operating conditions, which does not consider the effect of internal dynamics of rolling bearing. In this paper, the effects of the applied load and bearing rotational speed on the lubrication performance in an angular contact ball bearing are conducted, which combines the bearing dynamic analysis and thermo-elastohydrodynamic lubrication (TEHL) analysis. First, the internal motions and contact forces are obtained from the developed bearing dynamic model, and then were integrated into the TEHL model to investigate the lubrication performance of the bearing. The results show that the rotational speed and external load has significant effects on film thickness, temperature, and power loss; if the improper axial load is applied for certain bearing speed, the lubrication performance will deteriorate and thermal failure may occur; there exists critical load or speed to keep good lubrication performance and avoid thermal failure; the skidding contributes to the thermal failure and bad lubrication performance.

scholarly journals Prediction of railway induced ground vibration through multibody and finite element modelling

2013 ◽  
Vol 4 (1) ◽  
pp. 167-183 ◽  
Author(s):  
G. Kouroussis ◽  
O. Verlinden
Keyword(s):  
Finite Element ◽  
High Speed ◽  
Vertical Plane ◽  
Time History ◽  
Ground Vibration ◽  
Element Model ◽  
Contact Forces ◽  
Railway Transportation ◽  
Lumped Mass ◽  
Mass Model

Abstract. The multibody approach is now recognized as a reliable and mature computer aided engineering tool. Namely, it is commonly used in industry for the design of road or railway vehicles. The paper presents a framework developed for predicting the vibrations induced by railway transportation. Firstly, the vehicle/track subsystem is simulated, on the basis of the home-made C++ library EasyDyn, by mixing the multibody model of the vehicle and the finite element model of the track, coupled to each other through the wheel/rail contact forces. Only the motion in the vertical plane is considered, assuming a total symmetry between left and right rails. This first step produces the time history of the forces exerted by the ballast on the foundation, which are then applied to a full 3-D FEM model of the soil, defined under the commercial software ABAQUS. The paper points out the contribution of the pitch motion of the bogies and carbodies which were neglected in previous publications, as well as the interest of the so-called coupled-lumped mass model (CLM) to represent the influence of the foundation in the track model. The potentialities of the model are illustrated on the example of the Thalys high-speed train, riding at 300 km h−1 on the Belgian site of Mévergnies.

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