Free and Forced Response of an Axially Moving String Transporting a Damped Linear Oscillator

1993 ◽  
Author(s):  
W. D. Zhu ◽  
C. D. Mote
Keyword(s):  
Initial Conditions ◽  
Numerical Algorithms ◽  
Time History ◽  
Coupled System ◽  
Interaction Force ◽  
Forced Response ◽  
Linear Oscillator ◽  
Response Analysis ◽  
History Of ◽  
Axially Moving

Abstract The transverse response of a cable transport system, which is modelled as an ideal, constant tension string travelling at constant speed between two supports with a damped linear oscillator attached to it, is predicted for arbitrary initial conditions, external forces and boundary excitations. The exact formulation of the coupled system reduces to a single integral equation of Volterra type governing the interaction force between the string and the payload oscillator. The time history of the interaction force is discontinuous for non-vanishing damping of the oscillator. These discontinuities occur at the instants when transverse waves propagating along the string interact with the oscillator. The discontinuities are treated using the theory of distributions. Numerical algorithms for computing the integrals involving generalized functions and for solution of the delay-integral-differential equation are developed. Response analysis shows a discontinuous velocity history of the payload attachment point. Special conditions leading to absence of the discontinuities above are given.

Experimental Forced Response Analysis of Two-Degree-of-Freedom Piecewise-Linear Systems With a Gap

2020 ◽  
Author(s):  
Akira Saito ◽  
Junta Umemoto ◽  
Kohei Noguchi ◽  
Meng-Hsuan Tien ◽  
Kiran D’Souza
Keyword(s):  
Piecewise Linear ◽  
Excitation Frequency ◽  
Forced Response ◽  
Degree Of Freedom ◽  
Linear Oscillator ◽  
Phase Portraits ◽  
Response Analysis ◽  
Experimental Setup ◽  
The Masses ◽  
Two Degree Of Freedom

Abstract In this paper, an experimental forced response analysis for a two degree of freedom piecewise-linear oscillator is discussed. First, a mathematical model of the piecewise linear oscillator is presented. Second, the experimental setup developed for the forced response study is presented. The experimental setup is capable of investigating a two degree of freedom piecewise linear oscillator model. The piecewise linearity is achieved by attaching mechanical stops between two masses that move along common shafts. Forced response tests have been conducted, and the results are presented. Discussion of characteristics of the oscillators are provided based on frequency response, spectrogram, time histories, phase portraits, and Poincaré sections. Period doubling bifurcation has been observed when the excitation frequency changes from a frequency with multiple contacts between the masses to a frequency with single contact between the masses occurs.

Simulation of Tip-Timing Measurements of a Cracked Bladed Disk Forced Response

2010 ◽  
Author(s):  
Vsevolod Kharyton ◽  
Jean-Pierre Laine ◽  
Fabrice Thouverez ◽  
Olexiy Kucher
Keyword(s):  
Dynamic Model ◽  
Harmonic Balance Method ◽  
Time History ◽  
Forced Response ◽  
Bladed Disk ◽  
Crack Behavior ◽  
Timing Data ◽  
History Of ◽  
Blade Tip ◽  
Blade Frequency

The study intends to simulate the process of the blade tip amplitude calculation by the tip-timing method. An attention is focused on tip-timing measurements for detection of a cracked blade from the bladed disk forced response. The cracked blade is considered within frameworks of the bladed disk dynamic model that takes into account mistuning presence. Nonlinear formulation of a crack behavior is done with the harmonic balance method in its combination with the contact analysis that allows simulation of crack breathing. In order to make the cracked blade detection process evident, the crack length and location are set in such a way as to produce the cracked blade frequency localization. Reconstruction of the blade tip amplitudes is attained with the arriving time of measured probes of the blade tips. The results are compared with the blade forced response obtained by the bladed disk dynamic model. A possibility is also considered how to reconstruct time-history of the bladed disk forced response with tip-timing data.

Identification of Vehicle-Bridge Interactive Forces From Measured Bridge Responses: Theoretical Studies

1995 ◽  
Author(s):  
S. S. Law ◽  
Tommy H. T. Chan ◽  
Q. H. Zeng
Keyword(s):  
Time History ◽  
Bending Moment ◽  
Highway Bridges ◽  
Interaction Force ◽  
Superposition Method ◽  
Vibration Data ◽  
Moving Force ◽  
Modal Superposition Method ◽  
History Of ◽  
Bridge Responses

Abstract Information of the vehicle-bridge interaction force is an important parameter in the design and evaluation of highway bridges. However it is difficult to directly measure or accurately calculate the force which is a moving force. The objective of this paper is to explore the theory of force identification based on the response of the structure to acquire a time history of the moving force. The force will be identified in time domain using a modal superposition method. A moving force on a simply supported beam is simulated, and the computational results show that the method is noise sensitive, and yet acceptable results can be obtained by combining the use of vibration data of the bending moment and acceleration measurements.

Forced Response Analysis of 2-DOF Piecewise-Linear Oscillator

2019 ◽  
Vol 2019 (0) ◽  
pp. 162
Author(s):  
Kohei Noguchi ◽  
Akira Saito ◽  
Meng-Hsuan Tien ◽  
Kiran D’Souza
Keyword(s):  
Piecewise Linear ◽  
Forced Response ◽  
Linear Oscillator ◽  
Response Analysis

The Dynamic Response Analysis on the Surrounding Ground of Underground Structure

2012 ◽  
Vol 204-208 ◽  
pp. 1301-1306
Author(s):  
Guo Dong Zhang ◽  
Jian Long Zhang ◽  
Jian Long Cao ◽  
Wen Luo
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Underground Structure ◽  
Time History ◽  
Limited Range ◽  
Seismic Effect ◽  
Response Analysis ◽  
Analysis Model ◽  
Element Analysis ◽  
History Of

Based on the theory of soil-structure interaction, the underground structure and surrounding soil as a system, and the finite element analysis model is established, and finite element dynamic analysis method is implemented, the three seismic acceleration time history of the different spectrum characteristics is inputted, the seismic effect on the surrounding ground of underground structure is analyzed. The results show that the effect on dynamic response is the limited range and not significant, when seismic design of structures on the surrounding sites is implemented, additional dynamic response on surrounding sites does not need to consider.

Panel Flutter Model Identification Using the Minimum Model Error Method on the Forced Response Measurements

2006 ◽  
Vol 128 (5) ◽  
pp. 635-645 ◽  
Author(s):  
Oleg V. Shiryayev ◽  
Joseph C. Slater
Keyword(s):  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Model Identification ◽  
Time History ◽  
Model Error ◽  
Forced Response ◽  
Response Data ◽  
Error System ◽  
Nonlinear State Space Models ◽  
Error Method

This work illustrates application of the minimum model error system identification method to obtain the nonlinear state space models of a fluttering panel. Identification using position and velocity data from forced response of the panel is presented here. The response was numerically simulated using two different discretization approaches: through finite differences and using the Galerkin’s method. Data from two different parts of response time history were considered. First, data where transients due to initial conditions and the forcing were present were used for identification. Then, data when only transients due to forcing were present were used for identification. The models obtained using the forced response of the panel were able to capture the behavior of the true system relatively accurately. Identification of models of different sizes is also discussed. Reduced size models can be successfully created from the forced response data using the minimum model error method. It is demonstrated that the number of degrees of freedom in the model attempted to be identified should be consistent with the number modes observed in the measurements. The response surface method was successfully applied to generate models for various flow regimes.

Seismic Response Analysis of the Fault Fracture Zones with Saturated Soil under Incident SV Waves

2014 ◽  
Vol 638-640 ◽  
pp. 1863-1868
Author(s):  
Long Sheng Wang ◽  
Zi Hui Wang ◽  
Hui Kong
Keyword(s):  
Seismic Response ◽  
Time History ◽  
Surface Displacement ◽  
Saturated Soil ◽  
Response Analysis ◽  
Soil Thickness ◽  
Input Method ◽  
Fault Fracture Zone ◽  
History Of ◽  
Dynamic Time

Based on viscous-spring artificial boundary of time domain and the corresponding wave input method, the dynamic time history of fault fracture zone containing saturated soil is studied when SV waves are imported vertically into it. The change of saturated soil thickness, angle and width of the fault has influence on the site seismic response, and the influence is analyzed and discussed. Studies show that the peak value of the fault’s surface displacement decreases slightly when the fault has a dip; and the influence of the width of fault containing saturated soil on seismic response of the site is small.

scholarly journals Nonlinear Dynamic Analysis of Axially Moving Laminated Shape Memory Alloy Beam with 1:3 Internal Resonance

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4022
Author(s):  
Ying Hao ◽  
Ming Gao ◽  
Yuda Hu ◽  
Yuehua Li
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Axial Velocity ◽  
Nonlinear Dynamic ◽  
Internal Resonance ◽  
Initial Conditions ◽  
Nonlinear Dynamic Analysis ◽  
Time History ◽  
Resonance Amplitude ◽  
Axially Moving

The remarkable properties of shape memory alloys (SMA) are attracting significant technological interest in many fields of science and engineering. In this paper, a nonlinear dynamic analytical model is developed for a laminated beam with a shape memory alloy layer. The model is derived based on Falk’s polynomial model for SMAs combined with Timoshenko beam theory. In addition, axial velocity, axial pressure, temperature, and complex boundary conditions are also parameters that have been taken into account in the creation of the SMA dynamical equation. The nonlinear vibration characteristics of SMA laminated beams under 1:3 internal resonance are studied. The multi-scale method is used to solve the discretized modal equation system, the characteristic equation of vibration modes coupled to each other in the case of internal resonance, as well as the time-history and phase diagrams of the common resonance amplitude in the system are obtained. The effects of axial velocity and initial conditions on the nonlinear internal resonance characteristics of the system were also studied.

Statistical Methods for Prediction of Characteristic Loads for Free Fall Lifeboats Based on CFD Screening Results

2013 ◽  
Author(s):  
Vidar Tregde ◽  
Arne Nestegård
Keyword(s):  
Environmental Conditions ◽  
Time History ◽  
Free Fall ◽  
Response Analysis ◽  
Short Term ◽  
Sea State ◽  
Screening Process ◽  
History Of ◽  
Term Analysis

Computational Fluid Dynamics (CFD) has been used in a screening process to calculate characteristic loads for a Free Fall Lifeboat (FFLB) during impact and submergence. The link between various input, e.g. environmental conditions and host specific data, resulting structural loads and motion of the lifeboat is explored. The screening can be used together with host specific environmental conditions to find structural design loads and motion restrictions. Response based analysis have been developed for both short term and long term predictions. For the short term predictions a sea state given by (Hs, Tp) on the 100-year contour line is identified and a three hour irregular sea state is simulated. This time history of surface elevations is used for a large number of random lifeboat drops. From these random drops a distribution of wave height and corresponding wave steepness is derived which is then input to an interpolation in the database of CFD screening results. The resulting responses are fitted to a Weibull distribution and the 90% quantile in this short term load distribution is determined. The long term response analysis is further developed from the short term analysis. The short term distributions for each (Hs, Tp) are combined with the probability of occurrence of the sea state, and long term distributions are derived for the responses similar to the short term analysis. The screening results are used to identify critical load cases which are further investigated.

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