Output-Only Analysis for Modal Parameters Estimation of an Elastically Scaled Ship

2008 ◽  
Vol 52 (01) ◽  
pp. 45-56
Author(s):  
Giuliano Coppotelli ◽  
Daniele Dessi ◽  
Riccardo Mariani ◽  
Marcello Rimondi
Keyword(s):  
Life Prediction ◽  
Structural Response ◽  
Random Excitation ◽  
Parameters Estimation ◽  
Elastic Response ◽  
Modal Parameters ◽  
Practical Application ◽  
Scaled Model ◽  
Output Only ◽  
Ship Speed

The study of the ship structural response assumes an increasing importance as soon as the structures, characterized by much more lightness, are designed and built for faster vessels. This requisite implies a greater flexibility of the structures themselves, the elastic response of which has to be evaluated with accuracy in order to predict the dynamic behavior. In the present paper, a methodology for the identification of the modal parameters from the measurement of only the responses of a vibrating structure has been developed and applied to an elastically scaled model. This output-only technique is successfully applied to the segmented model of a real ship towed in the INSEAN linear basin. The broadband random excitation, provided by the loads exerted by an irregular sea pattern, induces a stochastic response of the model, which is monitored with accelerometers. The obtained results not only outline the parametric dependence of the modal properties on the ship speed, but also suggest a possible practical application of this technique for on-board structural monitoring and fatigue-life prediction.

Remaining useful life prediction method for machine tools based on meta-action theory

2021 ◽  
pp. 1748006X2110025
Author(s):  
Zongyi Mu ◽  
Yan Ran ◽  
Genbao Zhang ◽  
Hongwei Wang ◽  
Xin Yang
Keyword(s):  
Machine Tools ◽  
Life Prediction ◽  
Action Theory ◽  
Prediction Method ◽  
Operational Reliability ◽  
Remaining Useful Life ◽  
Practical Application ◽  
Dynamic Prediction ◽  
Degradation Model ◽  
Useful Life

Remaining useful life (RUL) is a crucial indictor to measure the performance degradation of machine tools. It directly affects the accuracy of maintenance decision-making, thus affecting operational reliability of machine tools. Currently, most RUL prediction methods are for the parts. However, due to the interaction among the parts, even RUL of all the parts cannot reflect the real RUL of the whole machine. Therefore, an RUL prediction method for the whole machine is needed. To predict RUL of the whole machine, this paper proposes an RUL prediction method with dynamic prediction objects based on meta-action theory. Firstly, machine tools are decomposed into the meta-action unit chains (MUCs) to obtain suitable prediction objects. Secondly, the machining precision unqualified rate (MPUR) control chart is used to conduct an out of control early warning for machine tools’ performance. At last, the Markov model is introduced to determine the prediction objects in next prediction and the Wiener degradation model is established to predict RUL of machine tools. According to the practical application, feasibility and effectiveness of the method is proved.

Improving the accuracy of SOD for modal parameters estimation of damped systems

2014 ◽  
Vol 226 (6) ◽  
pp. 1673-1687 ◽  
Author(s):  
Mousa Rezaee ◽  
Gholamreza Fattahi Yam
Keyword(s):  
Parameters Estimation ◽  
Modal Parameters ◽  
Damped Systems

Real-time vision-based modal parameters estimation at 10000 fps

2012 ◽  
Author(s):  
Hua Yang ◽  
Idaku Ishii ◽  
Takeshi Takaki
Keyword(s):  
Real Time ◽  
Parameters Estimation ◽  
Modal Parameters

scholarly journals Output-Only Modal Analysis Based on Improved Empirical Mode Decomposition Method

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Shiqiang Qin ◽  
Qiuping Wang ◽  
Juntao Kang
Keyword(s):  
Modal Analysis ◽  
Empirical Mode Decomposition ◽  
Modal Parameters ◽  
Band Pass Filter ◽  
Pass Filter ◽  
Random Decrement Technique ◽  
Mode Decomposition ◽  
Frequency Components ◽  
Output Only ◽  
Emd Method

The output-only modal analysis for bridge structures based on improved empirical mode decomposition (EMD) is investigated in this study. First, a bandwidth restricted EMD is proposed for decomposing nonstationary output measurements with close frequency components. The advantage of bandwidth restricted EMD to standard EMD is illustrated by a numerical simulation. Next, the modal parameters are extracted from intrinsic mode function obtained from the improved EMD by both random decrement technique and stochastic subspace identification. Finally, output-only modal analysis of a railway bridge is presented. The study demonstrates the mode mixing issues of standard EMD can be restrained by introducing bandwidth restricted signal. Further, with the improved EMD method, band-pass filter is no longer needed for separating the closely spaced frequency components. The modal parameters extracted based on the improved EMD method show good agreement with those extracted by conventional modal identification algorithms.

Railway Bridges Identification Techniques

2005 ◽  
Author(s):  
Luigi Garibaldi ◽  
Luigi Bregant ◽  
Claudio Valente ◽  
Fabio Brancaleoni ◽  
Giuseppe Catania
Keyword(s):  
Reference Model ◽  
Random Access ◽  
Random Excitation ◽  
Correct Identification ◽  
Railway Bridges ◽  
The Road ◽  
Alternative Techniques ◽  
Road Surface Roughness ◽  
Output Only ◽  
Identification Techniques

Output-only methodologies are nowadays well established to extract modal parameters in many areas of engineering, such as civil, mechanical and aeronautical. In the past, civil engineering tests have been mainly developed for road bridges, with the vehicle passage over the bridge deck representing the main source of excitation with some contribution given by the ambient noise. In the road bridge cases, the excitation is considered to be a function of the road surface roughness, the vehicles speed, the weight and suspension vehicles characteristics, and also the random access of the vehicles over the bridge, whilst for the railway case, not all these issues are correctly addressed, and other characteristics rise-up, possibly advantageous for a correct identification process; to demonstrate this statement, we can bear in mind how the random access of the vehicles becomes meaningless for railway bridges, the single train being a quasi deterministic source; furthermore, the influence of the train weight should be considered if compared to usual road vehicles. Since output-only techniques are conceived for random excitation noise, their use in these conditions is considerably stressed and special care, or alternative techniques, has to be considered to avoid errors. In this sense, the bridge reference model becomes more important and some special techniques have to be developed.

scholarly journals Real Time Estimation of Modal Parameters and Their Quality Assessment

2008 ◽  
Vol 15 (3-4) ◽  
pp. 299-306 ◽  
Author(s):  
Tadeusz Uhl ◽  
Maciej Petko ◽  
Grzegorz Karpiel ◽  
Andrzej Klepka
Keyword(s):  
Laboratory Test ◽  
Quality Assessment ◽  
Real Time ◽  
Time Estimation ◽  
Parameters Estimation ◽  
Modal Parameters ◽  
Recursive Method ◽  
Test Rig ◽  
Confidence Bounds ◽  
Real Time Estimation

In this paper the recursive method for modal parameters estimation is formulated and verified. Formulated algorithms are implemented in the FPGA electronic chip. As a result, the modal parameters and confidence bounds for the modal parameters are obtained in real time. The algorithms and their implementations are tested on laboratory test rig data and applied to – flight modal analysis of an airframe structure.

scholarly journals Response analysis of random base excitation ona magnetic bearing rotor system

2019 ◽  
Vol 293 ◽  
pp. 04004
Author(s):  
Jinping Chen ◽  
Li Zhang ◽  
Yanyan Luo ◽  
Haining Zhang ◽  
Jun Liu
Keyword(s):  
Collision Detection ◽  
Random Excitation ◽  
Magnetic Bearing ◽  
Rotor System ◽  
Response Analysis ◽  
Random Response ◽  
Practical Application ◽  
External Disturbances ◽  
Response Characteristics ◽  
Auxiliary Bearing

The magnetic bearing-rotor system is subject to various external disturbances in practical application. Under certain control conditions, the random response characteristics of the magnetic bearing-rotor system are a particular concern. This paper analyzes the response characteristics of base of the magnetic bearing subjected to acceleration random excitation in the horizontal direction. First, the magnetic bearing-rotor system model is deduced. Then, the random response of the rotor under acceleration random excitation is derived. The probability of the collision of the rotor between the auxiliary bearing is calculated and the example is given. The paper conclusion provides a theoretical basis for the collision detection and prediction of the magnetic bearing-rotor system.

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