Simulation of Engine Vibration on Nonlinear Hydraulic Engine Mounts

2005 ◽  
Author(s):  
A. R. Ohadi ◽  
G. Maghsoodi
Keyword(s):  
Equations Of Motion ◽  
Low Frequency ◽  
Governing Equations ◽  
Engine Mounts ◽  
Engine Vibration ◽  
Engine Mount ◽  
Rotational Motions ◽  
The Time Domain ◽  
Nonlinear Equations Of Motion ◽  
Four Cylinders

In this paper, vibration behavior of engine on nonlinear hydraulic engine mount including inertia track and decoupler is studied. In this regard, after introducing the nonlinear factors of this mount (i.e. inertia and decoupler resistances in turbulent region), the vibration governing equations of engine on one hydraulic engine mount are solved and the effect of nonlinearity is investigated. In order to have a comparison between rubber and hydraulic engine mounts, a 6 degree of freedom four cylinders V-shaped engine under inertia and balancing masses forces and torques is considered. By solving the time domain nonlinear equations of motion of engine on three inclined mounts, translational and rotational motions of engines body are obtained for different engine speeds. Transmitted base forces are also determined for both types of engine mount. Comparison of rubber and hydraulic mounts indicates the efficiency of hydraulic one in low frequency region.

Simulation of Engine Vibration on Nonlinear Hydraulic Engine Mounts

2007 ◽  
Vol 129 (4) ◽  
pp. 417-424 ◽  
Author(s):  
A. R. Ohadi ◽  
G. Maghsoodi
Keyword(s):  
Equations Of Motion ◽  
Low Frequency ◽  
Governing Equations ◽  
Engine Mounts ◽  
Engine Vibration ◽  
Engine Mount ◽  
Rotational Motions ◽  
The Time Domain ◽  
Nonlinear Equations Of Motion ◽  
Six Degree Of Freedom

In this paper, vibration behavior of engine on the nonlinear hydraulic engine mount, including inertia track and decoupler, is studied. In this regard, after introducing the nonlinear factors of this mount (i.e., inertia and decoupler resistances in turbulent region), the vibration governing equations of engine on one hydraulic engine mount are solved and the effect of nonlinearity is investigated. In order to have a comparison between the rubber and the hydraulic engine mounts, a six-degree-of-freedom four-cylinder V-shaped engine under shaking and balancing mass forces and torques is considered. By solving the time domain nonlinear equations of motion of the engine on three inclined mounts, translational and rotational motions of an engine body are obtained for different engine speeds. Transmitted base forces are also determined for both types of engine mount. Comparison of rubber and hydraulic mounts indicates the efficiency of a hydraulic one in the low-frequency region.

Less=Moor: A Time-Efficient Computational Tool to Assess the Behavior of Moored Ships in Waves

2017 ◽  
Author(s):  
Yijun Wang ◽  
Alex van Deyzen ◽  
Benno Beimers
Keyword(s):  
Dynamic Response ◽  
Research Effort ◽  
Equations Of Motion ◽  
Line Tension ◽  
Mooring Line ◽  
Induced Response ◽  
Wave Forces ◽  
Computational Tool ◽  
The Time Domain ◽  
Nonlinear Equations Of Motion

In the field of port design there is a need for a reliable but time-efficient method to assess the behavior of moored ships in order to determine if further detailed analysis of the behavior is required. The response of moored ships induced by gusting wind and/or waves is dynamic. Excessive motion response may cause interruption of the (un)loading operation. High line tension may cause lines to snap, introducing dangerous situations. A (detailed) Dynamic Mooring Analysis (DMA), however, is often a time-consuming and expensive exercise, especially when responses in many different environmental conditions need to be assessed. Royal HaskoningDHV has developed a time-efficient computational tool in-house to assess the wave (sea or swell) induced dynamic response of ships moored to exposed berths. The mooring line characteristics are linearized and the equations of motion are solved in the frequency domain with both the 1st and 2nd wave forces taken into account. This tool has been termed Less=Moor. The accuracy and reliability of the computational tool has been illustrated by comparing motions and mooring line forces to results obtained with software that solves the nonlinear equations of motion in the time domain (aNySIM). The calculated response of a Floating Storage and Regasification Unit (FSRU) moored to dolphins located offshore has been presented. The results show a good comparison. The computational tool can therefore be used to indicate whether the wave induced response of ships moored at exposed berths proves to be critical. The next step is to make this tool suitable to assess the dynamic response of moored ships with large wind areas, e.g. container ships, cruise vessels, RoRo or car carriers, to gusting wind. In addition, assessment of ship responses in a complicated wave field (e.g. with reflected infra-gravity waves) also requires more research effort.

A New Displacement Form for the Nonlinear Equations of Motion of Shells of Revolution

1985 ◽  
Vol 52 (3) ◽  
pp. 507-509 ◽  
Author(s):  
J. G. Simmonds
Keyword(s):  
Boundary Conditions ◽  
Nonlinear Equations ◽  
Equations Of Motion ◽  
Shells Of Revolution ◽  
Governing Equations ◽  
Hoop Strain ◽  
Axisymmetric Motion ◽  
Nonlinear Equations Of Motion ◽  
Surface Loads ◽  
Theory Of Shells

In the theory of shells of revolution undergoing torsionless, axisymmetric motion, an extensional and a bending hoop strain are introduced that are linear in the displacements, regardless of the magnitudes of the strains and the meridional rotation. The resulting equations of motion and boundary conditions are derived and some common conservative surface loads are listed along with their potentials. The governing equations appear to be the simplest possible in terms of displacements.

Numerical Simulation of Flutter of Suspension Bridges

1997 ◽  
Vol 50 (11S) ◽  
pp. S174-S179 ◽  
Author(s):  
S. Preidikman ◽  
D. T. Mook
Keyword(s):  
Control Systems ◽  
Equations Of Motion ◽  
Linear Equations ◽  
Suspension Bridges ◽  
Governing Equations ◽  
Nonlinear Springs ◽  
Linear Equations Of Motion ◽  
The Time Domain ◽  
Present Simulation ◽  
Post Onset

A method for simulating the spontaneous, wind-excited vibrations of suspension bridges is described. The approach is based on a numerical model that treats the bridge and flowing air as elements of a single dynamic system; and all of the governing equations are integrated numerically, simultaneously, and interactively. It is shown that the present simulation predicts the same onset of flutter as the analysis of Fung. Unlike Fung’s analysis, the present analysis provides the solution in the time domain, is not restricted to periodic motions or linear equations of motion, and provides post-onset behavior as long as the effective angles of attack are not large enough to produce stall. As a consequence, the present analysis can be a very effective tool for the design of flutter-suppressing control systems. Because the equations are solved numerically, nonlinear supports do not present a problem. In the present work, it is shown how the nonlinear springs lead to limit-cycle responses.

Nonlinear Vibration Analysis of a Cable Carrying Moving Mass-Spring-Damper

2018 ◽  
Vol 18 (02) ◽  
pp. 1850030 ◽  
Author(s):  
M. Ghadiri ◽  
M. Kazemi
Keyword(s):  
Mutual Influence ◽  
Equations Of Motion ◽  
Vertical Motion ◽  
Vertical Movement ◽  
Tangential Component ◽  
Governing Equations ◽  
Acceleration Method ◽  
The Time Domain ◽  
Mass Spring ◽  
Moving Oscillator

In this study, nonlinear dynamics and vibrations of a mass, spring and damper system with constant and variable velocities have been investigated. One end of the large-sag cable is fixed and the other one can be varied using different heights with respect to the first end. The oscillator can be accelerated by the tangential component of the weight force. The governing equations of motion are derived with regard to the mutual influence of the cable movement and vertical motion of attached mass. The Galerkin’s method is employed in the displacement field in conjunction with the average acceleration method in the time domain to solve the governing equations. The parametric study is performed on the vertical movement of the oscillator, the displacement of the cable and the velocity of the moving oscillator.

Dynamic Analysis of Engine-Mount Systems

1992 ◽  
Vol 114 (1) ◽  
pp. 79-83 ◽  
Author(s):  
H. Ashrafiuon ◽  
C. Nataraj
Keyword(s):  
Circular Plate ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Infinite Plate ◽  
Forced Response ◽  
Engine Vibration ◽  
Airplane Engine ◽  
Engine Mount ◽  
Industrial Rubber ◽  
Stiffness And Damping

This paper examines the forced response of an airplane engine supported by an elastic foundation. It is assumed that the vibrations of the engine and the foundation are small enough such that the equations of motion are linear. The engine is modeled as a rigid body connected to the foundation by standard industrial rubber mounts which act as three-dimensional springs with a significant amount of hysteresis damping. Three fundamental models of the foundation are considered; rigid, statically flexible, and dynamically flexible. In the flexible cases, the foundation is modeled as a clamped circular plate, infinite plate, or any structure identified by a finite element stiffness matrix. In all cases, the mass, stiffness, and damping matrices of the engine-mount system are constructed and the frequency response to the rotating unbalance is determined. For the infinite and clamped circular plate cases, analytical methods are used to determine the real and imaginary parts of the flexibility matrix at different frequencies in response to the harmonic forces transmitted to the plate through the rubber mounts. It is shown here that the foundation elasticity may have a significant effect on the engine vibration and the mounting forces transmitted from the engine to the structure. It is also shown that only the dynamic model of the foundation is able to capture the correct response of the system at frequencies close to the foundation’s natural frequencies.

scholarly journals Optimal fluid passageway design methodology for hydraulic engine mounts considering both low and high frequency performances

2019 ◽  
Vol 25 (21-22) ◽  
pp. 2749-2757
Author(s):  
Yuan Li ◽  
Jason Zheng Jiang ◽  
Simon A Neild
Keyword(s):  
High Frequency ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Relative Displacement ◽  
Wide Frequency Range ◽  
Performance Criteria ◽  
Frequency Model ◽  
Engine Mounts ◽  
Engine Mount ◽  
And Performance

This paper investigates the potential for improving the performance of hydraulic engine mounts through fluid passageway designs. In previous studies, a few simple inertia track designs have been investigated with moderate improvements obtained. However, there are countless alternative design possibilities existing; while analyzing each one of them in turn is impracticable. To this end, this paper introduces a systematic methodology to optimize fluid passageway designs in a hydraulic engine mount. First, beneficial fluid passageway configurations are systematically identified using a linearized low-frequency model that captures the relative displacement transmissibility. A nonlinear model is then used to fine-tune the fluid passageway designs for the low-frequency transmissibility improvement, and also for the assessment of high-frequency dynamic stiffness performance. The obtained beneficial designs present performance advantages over a wide frequency range. The design approach introduced in this study is directly applicable to other engine mount models and performance criteria.

scholarly journals Optimization of Classical Hydraulic Engine Mounts Based on RMS Method

2005 ◽  
Vol 12 (2) ◽  
pp. 119-147 ◽  
Author(s):  
J. Christopherson ◽  
G. Nakhaie Jazar
Keyword(s):  
Time Domain ◽  
Relative Displacement ◽  
Response Functions ◽  
Optimal Parameters ◽  
Absolute Acceleration ◽  
Engine Mounts ◽  
Engine Mount ◽  
The Absolute ◽  
Time Domain Response ◽  
The Time Domain

Based on RMS averaging of the frequency response functions of the absolute acceleration and relative displacement transmissibility, optimal parameters describing the hydraulic engine mount are determined to explain the internal mount geometry. More specifically, it is shown that a line of minima exists to define a relationship between the absolute acceleration and relative displacement transmissibility of a sprung mass using a hydraulic mount as a means of suspension. This line of minima is used to determine several optimal systems developed on the basis of different clearance requirements, hence different relative displacement requirements, and compare them by means of their respective acceleration and displacement transmissibility functions. In addition, the transient response of the mount to a step input is also investigated to show the effects of the optimization upon the time domain response of the hydraulic mount.

On the Vibrations of a Laminated Body

1968 ◽  
Vol 35 (4) ◽  
pp. 689-696 ◽  
Author(s):  
J. D. Achenbach ◽  
C. T. Sun ◽  
G. Herrmann
Keyword(s):  
Boundary Conditions ◽  
Equations Of Motion ◽  
Sufficient Conditions ◽  
Low Frequency ◽  
Continuum Theory ◽  
Acoustic Mode ◽  
Governing Equations ◽  
Natural Boundary ◽  
Natural Boundary Conditions ◽  
Laminated Layer

A continuum theory for a laminated medium is further developed in this paper. Constitutive equations, stress equations of motion, and natural boundary conditions are presented, and sufficient conditions for a unique solution are discussed. The governing equations and boundary conditions are employed to study the thickness-twist motion of a laminated layer. For every nodal number there is a low frequency acoustic mode and a high frequency optical mode. The frequencies of the acoustic modes are compared with the corresponding frequencies predicted by the effective modulus theory, and the relative magnitudes of the material parameters for which these frequencies are substantially at variance are indicated.

scholarly journals Suspended Decoupler: A New Design of Hydraulic Engine Mount

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
J. Christopherson ◽  
M. Mahinfalah ◽  
Reza N. Jazar
Keyword(s):  
Steady State ◽  
Transient Response ◽  
Equations Of Motion ◽  
State Behavior ◽  
Engine Mounts ◽  
Nonlinear Finite Elements ◽  
Lumped Parameter ◽  
Start Up ◽  
Engine Mount ◽  
Static Conditions

Because of the density mismatch between the decoupler and surrounding fluid, the decoupler of all hydraulic engine mounts (HEM) might float, sink, or stick to the cage bounds, assuming static conditions. The problem appears in the transient response of a bottomed-up floating decoupler hydraulic engine mount. To overcome the bottomed-up problem, a suspended decoupler design for improved decoupler control is introduced. The new design does not noticeably affect the mechanism's steady-state behavior, but improves start-up and transient response. Additionally, the decoupler mechanism is incorporated into a smaller, lighter, yet more tunable and hence more effective hydraulic mount design. The steady-state response of a dimensionless model of the mount is examined utilizing the averaging perturbation method applied to a set of second-order nonlinear ordinary differential equations. It is shown that the frequency responses of the floating and suspended decoupled designs are similar and functional. To have a more realistic modeling, utilizing nonlinear finite elements in conjunction with a lumped parameter modeling approach, we evaluate the nonlinear resorting characteristics of the components and implement them in the equations of motion.

Sign in / Sign up

Export Citation Format

Share Document