Method to Enhance the Frequency Readability for Detecting Incipient Structural Damage

The paper presents a procedure to precisely estimate the natural frequencies of structures. It implies the acoustic excitation of the structure and the evaluation of the frequencies from the response signals, involving an advanced method developed by the authors. The study is performed on a cantilever beam. To demonstrate the efficiency of the contrived procedure, the values of the frequencies by applying this procedure are compared whit those obtained by standard frequency estimation made for the response to an impulsive excitation.

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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A procedure for an accurate estimation of the natural frequencies of structures

Gillich¹,

Mituletu²,

Nedelcu³

et al. 2018

“…In addition, these methods can highlight the small frequency changes that are expected, and which are difficult to be observed in the initial stage of research by experiments. However, we have developed methods to increase the accuracy of frequency estimation [17][18][19] and the procedures to compare the modal parameters in the healthy and damaged state [20], so that we appreciate that in a mature stage the method to detect longitudinal cracks in weld joints of the I-beams will work efficiently.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity analysis for frequency-based prediction of cracks in open cross-section beams

Barbinta¹,

Tufiși²,

Hamat³

et al. 2019

The paper presents a study dedicated to analyzing the sensitivity of structures with open contours to cracks. For this purpose, we analyze the particular case of the I-beam made by welding, for which we want to see how the frequencies of different modes of vibration change when a crack occurs in the weld joint between the web and the flange. The research is done using numerical simulations performed with the ANSYS program, from which the natural frequencies are obtained depending on the depth and extent of the crack. A large number of vibration modes and two types of boundary conditions are taken into account. We found that the frequency changes are small but still detectable and depend on the beam fixation mode. This makes it possible to detect cracks in the weld joint if the vibration modes where the decrease in frequency is significant are analyzed.

“…In previous studies [15][16][17][18], the authors developed a robust method for detecting, locating and evaluating transverse cracks in all types of beams, regardless of the constraining method, based on the natural frequency changes.…”

Section: Introductionmentioning

confidence: 99%

Numerical study on complex shaped cracks in cantilever beams concerning frequency and stiffness changes

Tufiși¹,

Gillich²,

Nedelcu³

et al. 2018

The paper presents a mathematical relation to express the effects of a T-shaped crack on beam-like structures. The study is performed by using the finite element method (FEM) and contrived analytical formulas for proving the existing correlation between deflection, strain energy, and natural frequency changes. The damaged beam static and dynamic behaviors are analyzed by means of the FEM. The frequency shift for the first mode of vibration derived directly was compared with the frequency alteration calculated involving the change in the beam deflection for several scenarios of the T-shaped crack. The frequency shift is derived using the relations between deflection and natural frequency. As the final step in the research, we compared the outcomes for the same crack with the results achieved from a beam suffering a loss of stiffness.