Porovnání metod pro získání modálních parametrů při experimentální modální analýze

Comparison of Modal Parameter Estimation Techniques For Experimental Modal Analysis

conference paper

en

This paper deals with comparison of three commonly used modal parameter estimation methods (Pick Picking, Least Square Complex Exponential and Eigensystem Realization Algorithm) in order to judge about their accuracy and limitation. There have been invented a great amount of modal parameter estimation techniques in the field of experimental modal analysis. However, there is not universal method which would be suitable for every possible structure and/or with acceptable accuracy. As a test structure, 15 degrees of freedom plane with given mass, damping and stiffness was chosen. The foundations of discussed methods are described, their implementation on the test structure is shown and finally, natural frequencies and damping obtained by analytical approach are compared with those estimated using mentioned techniques. In addition, mode shapes differences are illustrated by means of Modal Assurance Criterion. Based on these comparisons, an accuracy and limitation of the methods is summarized in the conclusion.

Tato práce se zabývá srovnáním tří běžně používaných metod pro odhad modálních parametrů (Pick Picking, Least Square Complex Exponential a Eigensystem Realization Algorithm). Cílem bylo posoudit a ověřit jejich přesnost a omezení. Existuje mnoho metod pro stanovení modálních parametrů, avšak žádná není univerzální, která by byla vhodná pro všechny systémy s přijatelnou přesností. V tomto příspěvku byl použit jako tesovací struktura model desky s 15 stupni volnosti s definovaným tlumením a tuhosti. Pomocí jednotlivých metod byly získány vlastní frekvence a tlumení systému. Přesnosti a omezení jednotlivých metod jsou shrnuty v závěru.

This paper deals with comparison of three commonly used modal parameter estimation methods (Pick Picking, Least Square Complex Exponential and Eigensystem Realization Algorithm) in order to judge about their accuracy and limitation. There have been invented a great amount of modal parameter estimation techniques in the field of experimental modal analysis. However, there is not universal method which would be suitable for every possible structure and/or with acceptable accuracy. As a test structure, 15 degrees of freedom plane with given mass, damping and stiffness was chosen. The foundations of discussed methods are described, their implementation on the test structure is shown and finally, natural frequencies and damping obtained by analytical approach are compared with those estimated using mentioned techniques. In addition, mode shapes differences are illustrated by means of Modal Assurance Criterion. Based on these comparisons, an accuracy and limitation of the methods is summarized in the conclusion.

Experimentální modální analýza, určení modálních parametrů, modal assurance.

Experimental Modal Analysis, Modal Parameter Estimation, Modal Assurance Criterion

2014

12.05.2014

978-80-214-4871-1

ENGINEERING MECHANICS 2014

2014

460–463

762