scholarly journals Modelling of propeller shaft dynamics at pulse load

2008 ◽  
Vol 15 (4) ◽  
pp. 52-58 ◽  
Author(s):  
Andrzej Grządziela
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Model Identification ◽  
Experimental Results ◽  
Real Object ◽  
Pulse Load ◽  
Propeller Shaft ◽  
Matlab Simulink ◽  
External Agents ◽  
Time Histories

Modelling of propeller shaft dynamics at pulse load The article discusses a method of modelling of propeller shaft dynamics at the presence of virtually introduced underwater detonation effects. The propeller shaft model has four degrees of freedom, which provides opportunities for introducing shaft displacements and rotations similar to those observed in a real object. The equations of motion, taking into account the action of external agents, were implemented to the Matlab SIMULINK environment. The obtained time-histories and their spectra were compared with the experimental results of the tests performed on the marine testing ground. The performed model identification confirmed its sensitivity to changing parameters of motion and external actions.

Regular and Irregular Vibrations of a Non-Ideal Autoparametric System

Volume 2 ◽  
2004 ◽  
Author(s):  
Danuta Sado ◽  
Maciej Kot
Keyword(s):  
Energy Source ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Resonance Region ◽  
The Body ◽  
Damping Force ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Time Histories ◽  
Limited Power

This paper studies the regular and irregular vibrations of two degrees of freedom autoparametrical system, when the excitation is made by an electric motor (with unbalanced mass), which works with limited power supply. The investigated system consists of a pendulum of the length l and mass m, and a body of mass M suspended on the flexible element. It was assumed that the damping force acting on the body of mass M and resistive moment acting on the pedulum are non-linear. In this case, the excitation has to be expressed as an equation describing how the energy source supplies the energy to the system. The non-ideal source of power adds one degree of freedom, and then the system has three degrees of freedom. The system has been researched for known characteristic of the energy source (DC motor). The equations of motion have been solved numerically what permit to enrich the investigations and to examine not only small and steady state oscillations but also large-amplitude oscillations in transient states. The influence of motor’s speed on the phenomenon of energy transfer has been researched. Near the internal and external resonance region, except different kind of periodic vibration, the chaotic vibration has been observed. For characterizing an irregular chaotic response bifurcation diagrams and time histories, power spectral densities, Poincare´ maps and maximal exponents of Lyapunov have been constructed.

Comparative Study of the Linear and Non-Linear Locomotive Response

1979 ◽  
Vol 101 (3) ◽  
pp. 263-271 ◽  
Author(s):  
E. H. Chang ◽  
V. K. Garg ◽  
C. H. Goodspeed ◽  
S. P. Singh
Keyword(s):  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Design Parameters ◽  
Suspension Systems ◽  
Damping Characteristics ◽  
Time Histories ◽  
Steady State Responses ◽  
Stiffness And Damping ◽  
State Responses

A mathematical model for a six-axle locomotive is developed to investigate its dynamic response on tangent track due to vertical and/or lateral track irregularities. The model represents the locomotive as a system of thirty-nine degrees of freedom. The nonlinearities considered in the model are primarily associated with stiffness and damping characteristics of the primary suspension system. The transient and steady-state responses of the locomotive are obtained for the linear and nonlinear primary suspension systems. The response time-histories of the locomotive obtained by integrating the generalized equations of motion are presented. The potential uses of the model are indicated for studying the influence of different design parameters and predicting subsequent dynamic response.

scholarly journals Effect of Pulse Shape and Duration on Dynamic Response of a Forging System

2019 ◽  
Vol 13 (4) ◽  
pp. 226-232
Author(s):  
Arkadiusz Trąbka
Keyword(s):  
Dynamic Response ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Time History ◽  
Pulse Load ◽  
Negative Effects ◽  
Maximum Displacement ◽  
Soil Settlement ◽  
History Of ◽  
Three Degrees Of Freedom

Abstract Forging hammers are machines whose operation causes negative effects both at the place of their foundation (the soil settlement) and in their surroundings (e.g., vibrations propagating to the other devices, noise, etc.). Knowledge of the parameters characterizing the time history of the force that arises as a result of impact of a ram on a shaped material is of fundamental importance for the correct analysis of both the structure of the hammer and its impact on the surroundings. In the paper, the effect of the shape and duration of a pulse load on the dynamic response of a hammer-foundation forging system was assessed. An analytical method of description of the forces that arise as a result of impact of the ram on the forged material, using different forms of pulses was presented. The forces defined in this way as loads in a mathematical model of three degrees of freedom forging system were used. The equations of motion derived from d’Alembert’s principle were solved numerically in the Matlab program. The analyses for eight forms of the pulse loads with the same pulse sizes but different durations were performed. The results in the graphs were presented. It was found, among other things, that a greater impact on the maximum displacement, velocity and acceleration of each component of the hammer-foundation system as well as on the maximum forces transmitted to the soil has the duration of a pulse than its shape.

Segmental vibration transmissibility of seated occupant from lumped parameter models

2011 ◽  
Vol 18 (11) ◽  
pp. 1683-1689 ◽  
Author(s):  
Masilamany Santha Alphin ◽  
Krishnaswamy Sankaranarayanasamy ◽  
Suthangathan Paramashivan Sivapirakasam
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Biomechanical Model ◽  
Dynamic Parameter ◽  
Experimental Results ◽  
Lumped Parameter Model ◽  
Whole Body ◽  
Driving Frequency ◽  
Lumped Parameter ◽  
Lumped Parameter Models

One of the important parameters for the comfort of a seated occupant of a vehicle is the dynamic parameter. The effects of vibration depend on biomechanical characteristics, transmissibility (TR) and apparent mass. The range of input vibration at the seat and TR at the driving frequency will decide the magnitude of the displacement at any point of the human occupant. The most preferred form of biomechanical model for unidirectional whole body vibration is the lumped parameter model. Lumped parameter models are formulated by number of masses depending on the number of degrees-of-freedom (d.f.). The objective of this work is to study the vibration TR by developing the equations of motion (EOM) for different d.f. models for the seated occupant. Then the generated equations of motion for lumped parameter models are solved using the frequency domain technique. In this paper two, four, seven and 11 d.f. models are considered. The TR values are determined by solving the derived parameters using the MATLAB program. The maximum seats to head TR in the case of two, four, seven and 11 d.f. are obtained at the frequency of 2 Hz, 2.5 Hz, 3.15 Hz, and 4 Hz respectively. The TR obtained from models is compared with real time experimental results. The comparison shows a better fit for the TR obtained from the four and seven d.f. models. There is a wide deviation from the TR observed with two and 11 degrees of models when compared with experimental results of the past literature.

Modeling of Vertical Planar Two-Link Manipulator

2010 ◽  
Vol 164 ◽  
pp. 366-370
Author(s):  
Zdzisław Gosiewski ◽  
Grzegorz Michałowski
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Matlab Simulink ◽  
Hydraulic Cylinders ◽  
Simulation Results

Modeling of kinematics of hydraulically-driven manipulator is presented in the paper. The analyzed electrically-controlled vertical planar two-link manipulator has two rotary degrees of freedom and includes two hydraulic cylinders that form additional links thereby resulting in excavator type mechanism. Equations of motion are derived. Provided simulation results of the manipulator endpoint position, velocity, and acceleration are obtained by Matlab/Simulink.

The motion of a lunar orbiter

1966 ◽  
Vol 25 ◽  
pp. 373
Author(s):  
Y. Kozai
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Artificial Satellite ◽  
Equations Of Motion ◽  
Triaxial Ellipsoid ◽  
The Moon ◽  
Secular Motion ◽  
The Earth ◽  
Close Satellite ◽  
The Mean

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.

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.

Investigation of Train Dynamics in Passing Through Curves Using a Full Model

Joint Rail ◽  
2004 ◽  
Author(s):  
Mohammad Durali ◽  
Mohammad Mehdi Jalili Bahabadi
Keyword(s):  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Full Model ◽  
Bogie Frame ◽  
Nonlinear Characteristics ◽  
Train Derailment ◽  
Train Dynamics

In this article a train model is developed for studying train derailment in passing through bends. The model is three dimensional, nonlinear, and considers 43 degrees of freedom for each wagon. All nonlinear characteristics of suspension elements as well as flexibilities of wagon body and bogie frame, and the effect of coupler forces are included in the model. The equations of motion for the train are solved numerically for different train conditions. A neural network was constructed as an element in solution loop for determination of wheel-rail contact geometry. Derailment factor was calculated for each case. The results are presented and show the major role of coupler forces on possible train derailment.

Vibration analysis of multiple degrees of freedom mechanical system with dry friction

2012 ◽  
Vol 227 (7) ◽  
pp. 1505-1514 ◽  
Author(s):  
SD Yu ◽  
BC Wen
Keyword(s):  
Mechanical System ◽  
Dry Friction ◽  
Degrees Of Freedom ◽  
Simple Procedure ◽  
Mathematical Problem ◽  
Equations Of Motion ◽  
Inequality Constraints ◽  
Integration Scheme ◽  
Time Step ◽  
Multiple Degrees Of Freedom

This article presents a simple procedure for predicting time-domain vibrational behaviors of a multiple degrees of freedom mechanical system with dry friction. The system equations of motion are discretized by means of the implicit Bozzak–Newmark integration scheme. At each time step, the discontinuous frictional force problem involving both the equality and inequality constraints is successfully reduced to a quadratic mathematical problem or the linear complementary problem with the introduction of non-negative and complementary variable pairs (supremum velocities and slack forces). The so-obtained complementary equations in the complementary pairs can be solved efficiently using the Lemke algorithm. Results for several single degree of freedom and multiple degrees of freedom problems with one-dimensional frictional constraints and the classical Coulomb frictional model are obtained using the proposed procedure and compared with those obtained using other approaches. The proposed procedure is found to be accurate, efficient, and robust in solving non-smooth vibration problems of multiple degrees of freedom systems with dry friction. The proposed procedure can also be applied to systems with two-dimensional frictional constraints and more sophisticated frictional models.

Dynamic Modeling of a High-Dynamic Flight Simulator

2014 ◽  
Vol 687-691 ◽  
pp. 610-615 ◽  
Author(s):  
Hui Liu ◽  
Li Wen Guan
Keyword(s):  
Dynamic Modeling ◽  
Degrees Of Freedom ◽  
Flight Simulator ◽  
Inverse Dynamic ◽  
Dynamic Formulation ◽  
Time Histories ◽  
Rotational Degrees Of Freedom ◽  
High Dynamic ◽  
Euler Approach ◽  
Simulation Results

High-dynamic flight simulator (HDFS), using a centrifuge as its motion base, is a machine utilized for simulating the acceleration environment associated with modern advanced tactical aircrafts. This paper models the HDFS as a robotic system with three rotational degrees of freedom. The forward and inverse dynamic formulations are carried out by the recursive Newton-Euler approach. The driving torques acting on the joints are determined on the basis of the inverse dynamic formulation. The formulation has been implemented in two numerical simulation examples, which are used for calculating the maximum torques of actuators and simulating the time-histories of kinematic and dynamic parameters of pure trapezoid Gz-load command profiles, respectively. The simulation results can be applied to the design of the control system. The dynamic modeling approach presented in this paper can also be generalized to some similar devices.

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