Methods of Interpreting the Results of Vibration Measurements to Locate Damages in Beams

Minda, Petru Florin; Praisach, Zeno Iosif; Minda, Andrea Amalia; Gillich, Gilbert-Rainer

doi:10.4028/www.scientific.net/amm.430.84

Cited by 2 publications

(1 citation statement)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Usually, the frequency change caused by cracks compares to those achieved by using theoretical models. If more vibration modes are involved, the comparison is made by using dissimilarity estimators that perform a bin-by-bin evaluation [10][11][12]. It is possible to separate the problem of finding the crack location and severity by applying two consecutive normalizations [13].…”

Section: Introductionmentioning

confidence: 99%

Assessing multiple cracks in beams by a method based on the damage location coefficients

Gillich¹,

Aman²,

Nedelcu³

et al. 2019

Vib. proced.

View full text Add to dashboard Cite

In this paper, we analyze the case of structural integrity assessment when the beams have several cracks. The relationship between the location and the severity of one crack and the resulting frequency shift is known. That is why we can design databases containing many defects for which we can calculate precisely the frequency changes and the subsequent damage location coefficients. When the natural frequency evolution of several vibration modes is monitored, we can find alteration due to the crack. Comparing the results of the measurements with the values contained in the database, for instance by involving a bin-by-bin dissimilarity estimator, we can find the location and severity of the crack. For multiple cracks, this approach was not investigated. In this study, we design a database for two cracks affecting at the same time the beam. For these cracks, which have various severities and locations, we calculated the frequency changes by applying the superposition principle. Afterward, we find the frequency shifts for a test structure by means of the finite element method. The comparison between the damage location coefficients in the database and the signature of the damages achieved by simulation is made by the software we have developed in Visual Basic for Application in Excel. We succeed to find the severity and the location of the two cracks for all considered crack configurations.

show abstract

Section: Introductionmentioning

confidence: 99%

Assessing multiple cracks in beams by a method based on the damage location coefficients

Gillich¹,

Aman²,

Nedelcu³

et al. 2019

Vib. proced.

View full text Add to dashboard Cite

show abstract

About the calculus of the relative frequency shifts for a beam with multiple cracks

Gillich

Nedelcu

Hamat

et al. 2020

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

We propose in this paper a mathematical relationship to calculate the natural frequency shifts of beams due to multiple cracks. The relationship is based on the application of the superposition principle. A crack alters the frequencies for the bending vibration modes in a particular manner, with respect to the crack depth and location. We have shown that the affected beam have the same natural frequencies as a healthy beam with a smaller thickness; this thickness has to be calculated separately for each vibration mode. As a consequence, we can consider the next crack affects healthy beams, one different beam for each considered mode. Subsequent cracks affect a bigger number of beams. For the last crack, we have to calculate the frequencies for a number of beams that is the number of the considered vibration modes to the power equal with the number of cracks. To automate the process of calculating the resulted natural frequencies, we have written a program in Visual Basic for Excel Applications (VBEA), which permits finding the natural frequencies of a beam with up to nine cracks. This application can calculate the natural frequencies for four beam types: with fixed-free, fixed-fixed, simply supported and free-free restraints. The results obtained by calculating the frequencies for several damage scenarios and boundary conditions fit those obtained from simulations by involving the finite element method.

show abstract

Methods of Interpreting the Results of Vibration Measurements to Locate Damages in Beams

Cited by 2 publications

References 10 publications

Assessing multiple cracks in beams by a method based on the damage location coefficients

Assessing multiple cracks in beams by a method based on the damage location coefficients

About the calculus of the relative frequency shifts for a beam with multiple cracks

Contact Info

Product

Resources

About