scholarly journals Stochastic response determination of structural systems modeled via dependent coordinates: a frequency domain treatment based on generalized modal analysis

Meccanica ◽  
2019 ◽  
Vol 54 (9) ◽  
pp. 1421-1431 ◽  
Author(s):  
Antonina Pirrotta ◽  
Ioannis A. Kougioumtzoglou ◽  
Athanasios A. Pantelous
Keyword(s):  
Modal Analysis ◽  
Frequency Domain ◽  
Structural Systems ◽  
Stochastic Response ◽  
Response Determination ◽  
Dependent Coordinates

An Efficient Wiener Path Integral Technique Formulation for Stochastic Response Determination of Nonlinear MDOF Systems

2015 ◽  
Vol 82 (10) ◽  
Author(s):  
Ioannis A. Kougioumtzoglou ◽  
Alberto Di Matteo ◽  
Pol D. Spanos ◽  
Antonina Pirrotta ◽  
Mario Di Paola
Keyword(s):  
Path Integral ◽  
Computational Cost ◽  
High Dimensional ◽  
System Response ◽  
Stochastic Response ◽  
Mdof Systems ◽  
Low Dimensional ◽  
Response Determination ◽  
Efficiency And Reliability

The recently developed approximate Wiener path integral (WPI) technique for determining the stochastic response of nonlinear/hysteretic multi-degree-of-freedom (MDOF) systems has proven to be reliable and significantly more efficient than a Monte Carlo simulation (MCS) treatment of the problem for low-dimensional systems. Nevertheless, the standard implementation of the WPI technique can be computationally cumbersome for relatively high-dimensional MDOF systems. In this paper, a novel WPI technique formulation/implementation is developed by combining the “localization” capabilities of the WPI solution framework with an appropriately chosen expansion for approximating the system response PDF. It is shown that, for the case of relatively high-dimensional systems, the herein proposed implementation can drastically decrease the associated computational cost by several orders of magnitude, as compared to both the standard WPI technique and an MCS approach. Several numerical examples are included, whereas comparisons with pertinent MCS data demonstrate the efficiency and reliability of the technique.

Stochastic response determination of nonlinear oscillators with fractional derivatives elements via the Wiener path integral

2014 ◽  
Vol 38 ◽  
pp. 127-135 ◽  
Author(s):  
Alberto Di Matteo ◽  
Ioannis A. Kougioumtzoglou ◽  
Antonina Pirrotta ◽  
Pol D. Spanos ◽  
Mario Di Paola
Keyword(s):  
Path Integral ◽  
Fractional Derivatives ◽  
Nonlinear Oscillators ◽  
Stochastic Response ◽  
Response Determination

Error analyses of a Multi-Input-Multi-Output cantilever beam test

2021 ◽  
pp. 107754632110337
Author(s):  
Arup Maji ◽  
Fernando Moreu ◽  
James Woodall ◽  
Maimuna Hossain
Keyword(s):  
Transfer Function ◽  
Frequency Domain ◽  
Cantilever Beam ◽  
Transfer Functions ◽  
Linear Superposition ◽  
Transfer Function Matrix ◽  
Error Analyses ◽  
Pseudo Inverse ◽  
Function Matrix

Multi-Input-Multi-Output vibration testing typically requires the determination of inputs to achieve desired response at multiple locations. First, the responses due to each input are quantified in terms of complex transfer functions in the frequency domain. In this study, two Inputs and five Responses were used leading to a 5 × 2 transfer function matrix. Inputs corresponding to the desired Responses are then computed by inversion of the rectangular matrix using Pseudo-Inverse techniques that involve least-squared solutions. It is important to understand and quantify the various sources of errors in this process toward improved implementation of Multi-Input-Multi-Output testing. In this article, tests on a cantilever beam with two actuators (input controlled smart shakers) were used as Inputs while acceleration Responses were measured at five locations including the two input locations. Variation among tests was quantified including its impact on transfer functions across the relevant frequency domain. Accuracy of linear superposition of the influence of two actuators was quantified to investigate the influence of relative phase information. Finally, the accuracy of the Multi-Input-Multi-Output inversion process was investigated while varying the number of Responses from 2 (square transfer function matrix) to 5 (full-rectangular transfer function matrix). Results were examined in the context of the resonances and anti-resonances of the system as well as the ability of the actuators to provide actuation energy across the domain. Improved understanding of the sources of uncertainty from this study can be used for more complex Multi-Input-Multi-Output experiments.

Investigation of Impact Profile and Isolation Effect in Automated Impact Device Design and Control for Operational Modal Analysis

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Z. C. Ong ◽  
C. C. Lee
Keyword(s):  
Modal Analysis ◽  
Isolation Effect ◽  
Time Averaging ◽  
Impact Device ◽  
Lack Of Information ◽  
Analysis Technique ◽  
And Control ◽  
Phase Angles ◽  
Synchronous Time

A novel modal analysis technique called impact-synchronous modal analysis (ISMA) was introduced in previous research. With the utilization of impact-synchronous time averaging (ISTA), this modal analysis can be performed in presence of ambient forces whereas the conventional analysis method requires machines to be totally shut down. However, lack of information of phase angles with respect to impact in ISMA has caused it to be labor-intensive and time-consuming. An automated impact device (AID) is introduced in this study in the effort to replace the manually operated impact hammer and prepare it to be used in the current practice of ISMA on the purpose of enhancing its effectiveness and practicability. Impact profile and isolation effect are noted to be the contributing parameters in this study. This paper devoted on calibrating and controlling of the AID which gives the desired impact profiles as compared to the manual impact hammer. The AID is found effective in the determination of dynamic characteristics when the device is isolated from the boundary condition of the test structure.

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