Transient Response of a Support Structure Excited by an Accelerating Unbalanced Rotor

1986 ◽  
Vol 53 (2) ◽  
pp. 417-423 ◽  
Author(s):  
F. Ellyin ◽  
Z. Wolanski
Keyword(s):  
Finite Element ◽  
Transient Response ◽  
Journal Bearing ◽  
Equations Of Motion ◽  
Graphical Form ◽  
System Response ◽  
Transient Vibration ◽  
Element Discretization ◽  
Unbalanced Rotor ◽  
Method Of Solution

The transient vibration of a beam supporting an unbalanced rotor is investigated using finite element discretization techniques. The rotor speed is time dependent to simulate transients at startup. The beam is low-tuned relative to the rotor operating speed. A rigid rotor shaft mounted in an oil-film bearing is considered. The “short-bearing” approximation and nonlinear performance of the journal bearing are assumed. The method of solution for transient response is based on direct integration of the system equations of motion using finite element in time formulation. The results of numerical anlaysis are presented in graphical form and discussed. One notes significant effects of the journal bearing on the system response.

Static and Dynamic Analysis of Capillary Compensated Hydrostatic Journal Bearings by Finite Element Method

1977 ◽  
Vol 99 (4) ◽  
pp. 478-484 ◽  
Author(s):  
D. V. Singh ◽  
R. Sinhasan ◽  
R. C. Ghai
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Journal Bearing ◽  
Dynamic Performance ◽  
Critical Mass ◽  
Equations Of Motion ◽  
Stability Studies ◽  
Static And Dynamic Analysis ◽  
Bearing System ◽  
Element Method

Using finite element method steady state and dynamic performance of a capillary compensated hydrostatic journal bearing have been investigated. For stability studies, the critical mass of the bearing system has been determined by Routh’s criterion. The locus of the journal center has been predicted by discretizing time and numerically integrating the equations of motion governing the journal bearing system.

Effect of Boundary Conditions on Transient Response of Sandwich Plates with Electrorheological Fluid Core

2011 ◽  
Vol 462-463 ◽  
pp. 372-377
Author(s):  
Jafar Rahiminasab ◽  
Jalil Rezaeepazhand
Keyword(s):  
Finite Element ◽  
Electric Field ◽  
Boundary Conditions ◽  
Transient Response ◽  
Sandwich Plate ◽  
Natural Frequencies ◽  
Plate Theory ◽  
Equations Of Motion ◽  
Electrorheological Fluid ◽  
Fluid Core

Electrorheological (ER) fluids are a kind of smart material whose rheological properties can be controlled by an external electric field. In the present paper, the transient vibration of a rectangular three layer sandwich plate with electrorheological fluid core is analyzed based on the classical plate theory. The Bingham plastic model is used to consider the post-yield behavior of ER fluid. The structure is modeled using a finite element method. Hamilton’s principle is employed to derive the finite element equations of motion. The constant average acceleration scheme is used to integrate the equations of motion. The effects of change in electric field and core thickness on the structure settling time and its natural frequencies are studied for various boundary conditions. The results show that the thickness of the core layer and the electric field strength has significant effects on damping behavior of the sandwich plate. When the applied electric field increases a linear decay in transient response of the structure is observed. It is also found that the electric field changes have no influence on the system natural frequencies.

Transient Response of Rotor-Bearing Systems

1974 ◽  
Vol 96 (2) ◽  
pp. 682-690 ◽  
Author(s):  
R. G. Kirk ◽  
E. J. Gunter
Keyword(s):  
Transient Response ◽  
Transient Analysis ◽  
Equations Of Motion ◽  
Present System ◽  
Flexible Rotor ◽  
Machine Performance ◽  
Extensive Evaluation ◽  
Rotor Bearing ◽  
Method Of Solution ◽  
Energy Principles

The equations of motion necessary to calculate the transient response of a multimass flexible rotor supported by nonlinear, damped bearings are derived from energy principles. Rotor excitation may be the result of imbalance, internal friction, rotor acceleration, nonlinear forces due to any number of bearing or seal stations, and gyroscopic couples developed from skewed disk effects. The method of solution for transient response simulation is discussed in detail and is based on extensive evaluation of numerical methods available for transient analysis. Examples of the application of transient response for the analysis of rotor bearing systems are presented and compared to actual machine performance. Recommendations for the use and extension of the present system simulation model are discussed.

Nonlinear transient response of rough symmetric two lobe hole entry hybrid journal bearing system

2016 ◽  
Vol 23 (2) ◽  
pp. 190-219 ◽  
Author(s):  
Satish C Sharma ◽  
Prashant B Kushare
Keyword(s):  
Surface Roughness ◽  
Transient Response ◽  
Journal Bearing ◽  
Equations Of Motion ◽  
Point Of View ◽  
Stability Point ◽  
Nonlinear Transient ◽  
The Stability ◽  
Bearing System ◽  
Nonlinear Transient Response

The present paper describes the effect of surface roughness orientation pattern on the nonlinear transient response of symmetric two lobe capillary compensated hole entry hybrid journal bearing. Nonlinear equations of motion have been solved with the Runge-Kutta method. The stability of the journal bearing system has been studied by obtaining the journal center motion trajectories. The results of the study reveal that the surface roughness pattern significantly changes the stability of capillary compensated two lobe hole entry hybrid journal bearing. Hence, from the bearing stability point of view, a proper selection of the surface roughness pattern and bearing geometry is essential.

The Influence of Loading Position in A Priori High Stress Detection using Mode Superposition

2020 ◽  
Vol 1 (1) ◽  
pp. 93-102
Author(s):  
Carsten Strzalka ◽  
◽  
Manfred Zehn ◽  
Keyword(s):  
Finite Element ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
A Priori ◽  
High Stress ◽  
Von Mises Stress ◽  
Detailed Knowledge ◽  
Variable Loading ◽  
Numerical Effort ◽  
Von Mises

For the analysis of structural components, the finite element method (FEM) has become the most widely applied tool for numerical stress- and subsequent durability analyses. In industrial application advanced FE-models result in high numbers of degrees of freedom, making dynamic analyses time-consuming and expensive. As detailed finite element models are necessary for accurate stress results, the resulting data and connected numerical effort from dynamic stress analysis can be high. For the reduction of that effort, sophisticated methods have been developed to limit numerical calculations and processing of data to only small fractions of the global model. Therefore, detailed knowledge of the position of a component’s highly stressed areas is of great advantage for any present or subsequent analysis steps. In this paper an efficient method for the a priori detection of highly stressed areas of force-excited components is presented, based on modal stress superposition. As the component’s dynamic response and corresponding stress is always a function of its excitation, special attention is paid to the influence of the loading position. Based on the frequency domain solution of the modally decoupled equations of motion, a coefficient for a priori weighted superposition of modal von Mises stress fields is developed and validated on a simply supported cantilever beam structure with variable loading positions. The proposed approach is then applied to a simplified industrial model of a twist beam rear axle.

A New Approach to the Rigid Finite Element Method in Modeling Spatial Slender Systems

2018 ◽  
Vol 18 (02) ◽  
pp. 1850017 ◽  
Author(s):  
Iwona Adamiec-Wójcik ◽  
Łukasz Drąg ◽  
Stanisław Wojciech
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Analysis ◽  
Equations Of Motion ◽  
Nonlinear Dynamic Analysis ◽  
New Approach ◽  
Static And Dynamic Analysis ◽  
Rigid Finite Element Method ◽  
Longitudinal Flexibility ◽  
Element Method

The static and dynamic analysis of slender systems, which in this paper comprise lines and flexible links of manipulators, requires large deformations to be taken into consideration. This paper presents a modification of the rigid finite element method which enables modeling of such systems to include bending, torsional and longitudinal flexibility. In the formulation used, the elements into which the link is divided have seven DOFs. These describe the position of a chosen point, the extension of the element, and its orientation by means of the Euler angles Z[Formula: see text]Y[Formula: see text]X[Formula: see text]. Elements are connected by means of geometrical constraint equations. A compact algorithm for formulating and integrating the equations of motion is given. Models and programs are verified by comparing the results to those obtained by analytical solution and those from the finite element method. Finally, they are used to solve a benchmark problem encountered in nonlinear dynamic analysis of multibody systems.

Sign in / Sign up

Export Citation Format

Share Document