A time-domain seismic SSI analysis method for inelastic bridge structures through the use of a frequency-dependent lumped parameter model

2015 ◽  
Vol 44 (13) ◽  
pp. 2137-2156 ◽  
Author(s):  
Nikolaos Lesgidis ◽  
Oh-Sung Kwon ◽  
Anastasios Sextos
Keyword(s):  
Time Domain ◽  
Lumped Parameter Model ◽  
Analysis Method ◽  
Frequency Dependent ◽  
Lumped Parameter ◽  
Bridge Structures

Dynamic Forces From Single Gland Labyrinth Seals: Part I—Ideal and Viscous Decomposition

1994 ◽  
Vol 116 (4) ◽  
pp. 686-693 ◽  
Author(s):  
K. T. Millsaps ◽  
M. Martinez-Sanchez
Keyword(s):  
Inviscid Flow ◽  
Labyrinth Seal ◽  
Lumped Parameter Model ◽  
Solution Technique ◽  
Linear Perturbation ◽  
Labyrinth Seals ◽  
Frequency Dependent ◽  
Lumped Parameter ◽  
Reduced Parameters ◽  
Force Decomposition

A theoretical and experimental investigation on the aerodynamic forces generated by a single gland labyrinth seal executing a spinning/whirling motion has been conducted. A lumped parameter model, which includes the kinetic energy carryover effect, is presented along with a linear perturbation solution technique. The resulting system is nondimensionalized and the physical significance of the reduced parameters is discussed. Closed-form algebraic formulas are given for some simple limiting cases. It is shown that the total cross force predicted by this model can be represented as the sum of an ideal component due to an inviscid flow with entry swirl and a viscous part due to the change in swirl created by friction inside the gland. The frequency-dependent ideal part is solely responsible for the rotordynamic direct damping. The facility designed and built to measure these frequency dependent forces is described. Experimental data confirm the validity and usefulness of this ideal/viscous decomposition. A method for calculating the damping coefficients based on the force decomposition using the static measurements only is presented.

Dynamic Analysis and Multi-Object Optimization of the Forced Torsional Vibration for Vehicular Multi-Stage Planetary Gears

2011 ◽  
Vol 86 ◽  
pp. 263-267 ◽  
Author(s):  
Hui Liu ◽  
Zhong Chang Cai ◽  
Chang Le Xiang ◽  
Ming Zheng Wang
Keyword(s):  
Steady State ◽  
Time Domain ◽  
Torsional Vibration ◽  
Vibration Response ◽  
Resonance Vibration ◽  
Lumped Parameter Model ◽  
Lagrange Method ◽  
Planetary Gears ◽  
Multi Stage ◽  
Lumped Parameter

On the basis of lumped parameter model and the Lagrange method, the model of powertrain was built. Resonance vibration response and non-resonance vibration response were calculated respectively in time domain and frequency domain, characteristics of forced torsional vibration in steady–state were concluded. Comparability and difference of response of parts in different stage were explained. Multi-object optimization was applied to reduce vibration.

Research on Torsional Vibration of Gear-Shafting System Based on an Extended Lumped Parameter Model

2010 ◽  
Vol 143-144 ◽  
pp. 487-492 ◽  
Author(s):  
Xiang Xu ◽  
Rui Ping Zhou
Keyword(s):  
System Dynamics ◽  
Natural Frequency ◽  
Dynamic Simulation ◽  
Torsional Vibration ◽  
Lumped Parameter Model ◽  
Input Frequency ◽  
Analysis Method ◽  
Vibration Equation ◽  
Lumped Parameter ◽  
Marine Propulsion

In this paper, gear-shafting system dynamics theory has been introduced into the torsional vibration calculation of the marine propulsion shaft and the vibration equations of a marine gear-shafting system were established using the lumped parameter model by taking the gear-shafting system in marine propulsion shaft as the research object. In order to solve the problem of vibration equation, dynamic simulation has been done in MATLAB software, in which the natural frequency of the system has been obtained from the simulation curve by changing the input frequency, meanwhile, the conclusion that the gears pair comprehensive meshing error is independent of the system natural frequency has been achieved. Thus, the analysis method presented in this work is available for the torsional vibration calculation of the marine gear-shafting system.

Review of Early Work on Digital Displacement® Hydrostatic Transmission Systems

2018 ◽  
Author(s):  
Niall Caldwell
Keyword(s):  
Time Domain ◽  
Lumped Parameter Model ◽  
Primary Control ◽  
Hydrostatic Transmission ◽  
Load Sensing ◽  
Lumped Parameter ◽  
Good Comparison ◽  
Displacement Pump ◽  
Variable Displacement ◽  
Work Done

The paper describes the work done by the author (1) from 1999 to 2006 to develop the Digital Displacement Pump (DDP) and Pump/Motor (DDPM) and demonstrate the feasibility of off-highway vehicle applications. The link between DDPM capacity and the solenoid valve performance was identified. Magnetic geometry was improved by parametric FEA, then time-domain behavior was improved with a hybrid FEA/lumped-parameter model. Software improvements allowed variable speed and bidirectional operation, enabling the demonstration of the first Digital Displacement Transmission (DDT) systems on a vehicle, one featuring a load-sensing DDP and secondary control by DDPM displacement, and one featuring primary control by DDP displacement and a conventional axial motor. A time-domain simulation was created of the primary-controlled vehicle, which yielded good comparison to experimental results. The deterministic nature of the DDP lends itself to model-based system design methods, which have since been used to develop larger commercial systems. The first detailed analysis of DDP efficiency characteristics revealed profound differences to conventional variable displacement pumps, including exceptional part-load efficiency and the dominant effect of fluid compressibility. A peak overall efficiency of 97% was recorded for a DDP after analysis of loss sources prompted design improvement.

Research on Torsional Vibration of the Propulsion Shafting Gear System Based on an Extended Lumped Parameter Model

2010 ◽  
Vol 37-38 ◽  
pp. 1120-1124 ◽  
Author(s):  
Xiang Xu ◽  
Rui Ping Zhou
Keyword(s):  
Natural Frequency ◽  
Normal Condition ◽  
Torsional Vibration ◽  
Gear System ◽  
Lumped Parameter Model ◽  
Prototype Model ◽  
Analysis Method ◽  
Lumped Parameter ◽  
Marine Propulsion ◽  
Simulation Results

In this paper, gear dynamics theory has been introduced into the torsional vibration calculation of the marine propulsion shafting. The vibration equations of a marine gearbox were established using an extended lumped parameter model through reasonably adjusting the parameters to get the natural frequency of marine gearbox shafting gear system. The solution of the equations shows that under normal condition, the natural frequency of gear meshing transmission is high and the gearbox itself will not affect the torsional resonance. Then a virtual prototype model of marine gearbox was built by the use of ADAMAS software. The simulation results show that the proposed method could reflect the actual torsional vibration correctly. Thus, the analysis method presented in this work is available for the torsional vibration calculation of the marine gearbox.

A New Time Domain Multiple Input Modal Analysis Method

1987 ◽  
Vol 109 (4) ◽  
pp. 377-384 ◽  
Author(s):  
D. W. Cho ◽  
K. F. Eman ◽  
S. M. Wu
Keyword(s):  
Modal Analysis ◽  
Time Domain ◽  
Multivariate Time Series ◽  
Mode Shapes ◽  
Analysis Method ◽  
Parameter System ◽  
Oscillatory Systems ◽  
Structural Test ◽  
Lumped Parameter ◽  
Multiple Input

A time domain approach for multiple input modal analysis of oscillatory systems is proposed. The mathematical foundation for the approach is given along with its applications to a simulated lumped parameter system and the structural dynamics analysis of a milling machine. It has been shown that the proposed multivariate time series models are able to identify the complex mode shapes from multiple input structural test data. The advantages of the proposed method in comparison to existing methods are also highlighted.

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