Dynamic model updating based on strain mode shape and natural frequency using hybrid pattern search technique

2018 ◽  
Vol 422 ◽  
pp. 112-130 ◽  
Author(s):  
Ning Guo ◽  
Zhichun Yang ◽  
Le Wang ◽  
Yan Ouyang ◽  
Xinping Zhang
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Rahi Jain ◽  
Wei Xu

Abstract Background Developing statistical and machine learning methods on studies with missing information is a ubiquitous challenge in real-world biological research. The strategy in literature relies on either removing the samples with missing values like complete case analysis (CCA) or imputing the information in the samples with missing values like predictive mean matching (PMM) such as MICE. Some limitations of these strategies are information loss and closeness of the imputed values with the missing values. Further, in scenarios with piecemeal medical data, these strategies have to wait to complete the data collection process to provide a complete dataset for statistical models. Method and results This study proposes a dynamic model updating (DMU) approach, a different strategy to develop statistical models with missing data. DMU uses only the information available in the dataset to prepare the statistical models. DMU segments the original dataset into small complete datasets. The study uses hierarchical clustering to segment the original dataset into small complete datasets followed by Bayesian regression on each of the small complete datasets. Predictor estimates are updated using the posterior estimates from each dataset. The performance of DMU is evaluated by using both simulated data and real studies and show better results or at par with other approaches like CCA and PMM. Conclusion DMU approach provides an alternative to the existing approaches of information elimination and imputation in processing the datasets with missing values. While the study applied the approach for continuous cross-sectional data, the approach can be applied to longitudinal, categorical and time-to-event biological data.


1999 ◽  
Author(s):  
S. A. Lipsey ◽  
Y. W. Kwon

Abstract Damage reduces the flexural stiffness of a structure, thereby altering its dynamic response, specifically the natural frequency, damping values, and the mode shapes associated with each natural frequency. Considerable effort has been put into obtaining a correlation between the changes in these parameters and the location and amount of the damage in beam structures. Most numerical research employed elements with reduced beam dimensions or material properties such as modulus of elasticity to simulate damage in the beam. This approach to damage simulation neglects the non-linear effect that a crack has on the different modes of vibration and their corresponding natural frequencies. In this paper, finite element modeling techniques are utilized to directly represent an embedded crack. The results of the dynamic analysis are then compared to the results of the dynamic analysis of the reduced modulus finite element model. Different modal parameters including both mode shape displacement and mode shape curvature are investigated to determine the most sensitive indicator of damage and its location.


Author(s):  
Philippe Collignon ◽  
Jean-Claude Golinval

Abstract Failure detection and model updating using structural model are based on the comparison of an appropriate indicator of the discrepancy between experimental and analytical results. The reliability of the expansion of measured mode shapes is very important for the process of error localization and model updating. Two mode shape expansion techniques are examined in this paper : the well known dynamic expansion (DE) method and a method based on the minimisation of errors on constitutive equations (MECE). A new expansion method based on some improvements of the previous techniques is proposed to obtain results that are more reliable for error localisation and for model updating. The relative performance of the different expansion methods is demonstrated on the example of a cantilever beam.


2014 ◽  
Vol 538 ◽  
pp. 79-82
Author(s):  
Zhi Dong Huang ◽  
Yun Pu Du ◽  
Han Xiao Li ◽  
Xiu Li Sun ◽  
Yu Wang

The characteristics of oval gear is analyzed. The parameters of oval gear are chosen and calculated. The three-dimensional solid modeling of oval gear is achieved. The dynamic model of oval gear is established by FEM and modal analysis of oval gear is investigated. The natural frequency and major modes of the first six orders are clarified. The method and the result facilitate the dynamic design and dynamic response analysis of oval gear.


Author(s):  
Marwan Hassan ◽  
David S. Weaver

The development of a theoretical model for fluidelastic instability in tubes arrays is presented. Based on the simple model of Lever and Weaver, it considers a group of 7 tubes which move in both the streamwise and transverse directions. The analysis does not constrain either tube frequency or relative mode shape so that the tubes’ behaviour evolves from a perturbation naturally. No additional empirical input is required. A particular case is used to evaluate the model’s performance and the ratio of streamwise to transverse natural frequency is varied. Both streamwise and transverse fluidelastic instability are predicted and the results agree well with experimental observations.


2012 ◽  
Vol 163 ◽  
pp. 111-115 ◽  
Author(s):  
Wen Jing Wang ◽  
Li Ge Zhang ◽  
Shu Sheng Bi

Compliant mechanisms gain at least some of their mobility from the deflection of flexible members rather than from movable joints only. Dynamic effects are very important to improving the design of compliant mechanisms. An investigation on the dynamics and synthesis of the compliant mechanisms is presented. The dynamic model of compliant mechanisms is developed at first. The natural frequency and sensitivity are then studied based on the dynamic model. Finally, optimal design of compliant mechanism is investigated. The experimental study of natural frequency is performed. The comparison between the experiment results and the theoretical results verifies the validity of the experiment system and theoretical model.


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