WPA for Calculating Response Under Distributed Force Excitation

2020 ◽  
pp. 157-166
Author(s):  
Chongjian Wu
Keyword(s):  
Force Excitation

scholarly journals Vertical dynamics of a pantograph carbon-strip suspension under stochastic contact-force excitation

2013 ◽  
Vol 76 (1) ◽  
pp. 765-776 ◽  
Author(s):  
R. H. Huan ◽  
W. Q. Zhu ◽  
F. Ma ◽  
Z. G. Ying
Keyword(s):  
Contact Force ◽  
Force Excitation

scholarly journals Analytical and Numerical Investigation on the Duffing Oscilator Subjected to a Polyharmonic Force Excitation

2015 ◽  
Vol 45 (1) ◽  
pp. 3-16 ◽  
Author(s):  
Svetlin Stoyanov
Keyword(s):  
Fourier Transform ◽  
Analytical Solution ◽  
Discrete Time ◽  
Amplitude Modulation ◽  
Duffing Oscillator ◽  
Vibration Signal ◽  
Vibration Diagnostics ◽  
Significant Difference ◽  
Excitation Force ◽  
Force Excitation

Abstract An analytical solution for a specific case of the forced Duffing oscillator is proposed. The excitation force contains two harmonics with significant difference frequencies. This case corresponds to a presence of a defect in the machinery and is in the art of the machinery vibration diagnostics. The results obtained show an amplitude modulation. Therefore, the presence of an amplitude modulation in the vibration signal may be used as an indicator for a malfunction. Analytical solution derived clarifies how the amplitude modulation occurs. Also, a numerical solution is realized and compared with the analytical one. For this, the Duffing equation is solved numerically and then, the spectrograms of vibrations are obtained through a Discrete-time Fourier Transform.

Sound radiation from a double-leaf elastic plate with a point force excitation: effect of an interior panel on the structure-borne sound radiation

2002 ◽  
Vol 63 (7) ◽  
pp. 737-757 ◽  
Author(s):  
Motoki Yairi ◽  
Kimihiro Sakagami ◽  
Eiji Sakagami ◽  
Masayuki Morimoto ◽  
Atsuo Minemura ◽  
...  
Keyword(s):  
Elastic Plate ◽  
Sound Radiation ◽  
Point Force ◽  
Force Excitation

Drill String Vibrations Due to Intermittent Contact of Bit Teeth

1963 ◽  
Vol 85 (2) ◽  
pp. 187-194 ◽  
Author(s):  
P. R. Paslay ◽  
D. B. Bogy
Keyword(s):  
Experimental Data ◽  
Penetration Rate ◽  
Drill String ◽  
String Vibrations ◽  
Order Of Magnitude ◽  
Intermittent Contact ◽  
Maximum Penetration ◽  
Sufficient Magnitude ◽  
Force Excitation ◽  
Practical Measurement

An analysis of the longitudinal forces and the resulting longitudinal motions of an idealized drill string is presented. The only external force excitation considered occurs at the bit and is due to the intermittent contact of the teeth with the bottom of the hole. Attention has been restricted to the following two salient possibilities: 1 - Excitation at the bit may develop oscillating forces at the bit with amplitudes of the same order of magnitude as those of the bit load. 2 - Appreciable bit load variation may be detected by instruments which measure the motion of the drill string near its top. The first possibility is important if maximum penetration rate is to be achieved, and the second possibility is important in implementing practical measurement of the phenomenon. From the results of the specific example considered in this report, it is concluded that possibilities 1 and 2 may occur in sufficient magnitude to be influential, but experimental data on the actual bit motion and the damping will be required to evaluate the effect. The analysis is presented in such form that the influence of the various parts of the system can easily be evaluated.

Dynamics of Rotor/Bearing System With Flexible Rotor and Flexible Bearing Support

1997 ◽  
Author(s):  
Agnes Muszynska ◽  
Alex Petchenev ◽  
Paul Goldman
Keyword(s):  
Dynamic Stiffness ◽  
Stability Study ◽  
Modal Testing ◽  
Flexible Rotor ◽  
Dynamic Features ◽  
Sweep Frequency ◽  
Response Data ◽  
Lateral Modes ◽  
Force Excitation ◽  
Bearing System

Abstract The paper analyzes, theoretically and experimentally, the lowest four lateral modes of an isotropic rotor/fluid-lubricated bearing system with flexible rotor and flexible bearing support. The parameters of the analytical model of the system are identified using sweep-frequency modal testing of the rotor rig. A nonsynchronous, circular-rotating-force excitation was applied sequentially at the rotor and at the fluid-lubricated bearing casing, in order to generate the response data. The approach used in this study emphasizes the dynamic features of the system which are invariant to the choice of coordinate system. The system is described using Dynamic Stiffness matrix. This provides an advantage of simplicity, allowing a comprehensive stability study for various system parameters.

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