Fatigue Evaluation of Multi-Degree of Freedom, Frequency Domain, Stochastic, Truck Road Load Models

2019 ◽  
Vol 12 (1) ◽  
pp. 67-83 ◽  
Author(s):  
Karl Holmgren
Keyword(s):  
Frequency Domain ◽  
Degree Of Freedom ◽  
Load Models ◽  
Road Load ◽  
Fatigue Evaluation

A multi-axial vibration fatigue evaluation procedure for welded structures in frequency domain

2022 ◽  
Vol 167 ◽  
pp. 108516
Author(s):  
Xianjun Pei ◽  
Sandipp Krishnan Ravi ◽  
Pingsha Dong ◽  
Xiangwei Li ◽  
Xiaokun Zhou
Keyword(s):  
Frequency Domain ◽  
Evaluation Procedure ◽  
Axial Vibration ◽  
Welded Structures ◽  
Vibration Fatigue ◽  
Fatigue Evaluation

Effects of human-induced load models on tuned mass damper in reducing floor vibration

2019 ◽  
Vol 22 (11) ◽  
pp. 2449-2463
Author(s):  
Jun Chen ◽  
Ziping Han ◽  
Ruotian Xu
Keyword(s):  
Response Spectra ◽  
Tuned Mass Damper ◽  
Design Guidelines ◽  
Degree Of Freedom ◽  
Dynamic Responses ◽  
Single Degree Of Freedom ◽  
Load Model ◽  
Load Models ◽  
Single Degree ◽  
Mass Damper

Dozens of human-induced load models for individual walking and jumping have been proposed in the past decades by researchers and are recommended in various design guidelines. These models differ from each other in terms of function orders, coefficients, and phase angles. When designing structures subjected to human-induced loads, in many cases, a load model is subjectively selected by the design engineer. The effects of different models on prediction of structural responses and efficiency of vibration control devices such as a tuned mass damper, however, are not clear. This article investigates the influence of human-induced load models on performance of tuned mass damper in reducing floor vibrations. Extensive numerical simulations were conducted on a single-degree-of-freedom system with one tuned mass damper, whose dynamic responses to six walking and four jumping load models were calculated and compared. The results show a maximum three times difference in the acceleration responses among all load models. Acceleration response spectra of the single-degree-of-freedom system with and without a tuned mass damper were also computed and the response reduction coefficients were determined accordingly. Comparison shows that the reduction coefficient curves have nearly the same tendency for different load models and a tuned mass damper with 5% mass ratio is able to achieve 50%–75% response reduction when the structure’s natural frequency is in multiples of the walking or jumping frequency. All the results indicate that a proper load model is crucial for structural response calculation and consequently the design of tuned mass damper device.

Improving the Tracking of Generalized Predictive Control Controllers

1996 ◽  
Vol 210 (3) ◽  
pp. 169-182 ◽  
Author(s):  
J A Rossiter ◽  
B G Grinnell
Keyword(s):  
Frequency Domain ◽  
Predictive Control ◽  
Time Domain ◽  
Degree Of Freedom ◽  
Generalized Predictive Control ◽  
Control Law ◽  
Set Point ◽  
The Poor ◽  
Fixed Order ◽  
Two Degree Of Freedom

One of the advantages of predictive control is its ability to take optimal account of information about future set point changes in the specification of the control law. However, the optimum GPC (generalized predictive control) prefilter that uses this information can lead to a deterioration rather than an improvement in the accuracy of tracking. Some simple modifications to GPC to overcome this problem are discussed. It will then be shown how some simple algorithms can be used to design an optimal prefilter that does not have any of the poor effects arising from the standard choice and hence always improves the performance. The basis of the technique is analogous to the two-degree-of-freedom designs common in the literature on H∞. However, here the emphasis is on fixed-order prefilters designed from a time domain, not a frequency domain, objective.

Active Vibration Quenching Using Inverse Dynamics

1995 ◽  
Author(s):  
Thomas A. Trautt ◽  
Eduardo Bayo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Frequency Domain ◽  
Inverse Dynamics ◽  
Equations Of Motion ◽  
Input Function ◽  
Degree Of Freedom ◽  
The Finite Element Method ◽  
Simply Supported ◽  
Active Vibration

Abstract An inverse dynamics algorithm is derived for active vibration quenching of structures. The algorithm uses frequency domain technicques to compute an input function needed to produce a desired response at a particular degree of freedom. The desired response is a transition from the initial vibrating condition to a non-vibrating condition. The algorithm can also be used to modify the input function to correct for system disturbances while the input function is already being applied to the system. The algorithm is demostrated in a simulation of a simply supported beam controlled by a torque actuator at one end of the beam. The finite element method is used to discretize the equations of motion of the beam.

Frequency Domain Analysis of Multi-Degree of Freedom in Series Model SSI Effect with Translation and Rotation Input

2014 ◽  
Vol 1065-1069 ◽  
pp. 1457-1463
Author(s):  
Liang Fang ◽  
Qi Fang Wang
Keyword(s):  
Frequency Domain ◽  
Soil Structure ◽  
Correction Term ◽  
Mass Matrix ◽  
Frequency Domain Analysis ◽  
Degree Of Freedom ◽  
Soil Structure Interaction ◽  
Complex Matrix ◽  
Structure Interaction ◽  
In Series

Based on the multi-degree of freedom in series model, structural displacement amplitude formula is derived in the frequency domain under the translation-rotation input situation, this formula indicates that the soil - structure interaction (SSI) could be considered as adding a correction term M˜ to the mass matrix of the structure with the hypothesis of Rigid foundation. This corrected mass matrix is actually a complex matrix, which related to the input frequency and damping. Equivalent translation-rotation input is coupled with two translation input components U* and Θ*. Besides, we uses case analysis to explain the characteristics of soil - structure interaction (SSI) in frequency domain by the end of this paper.

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