Natural frequency changes due to damage in composite beams

Negru, Ionica; Gillich, Gilbert-Rainer; Praisach, Zeno-Iosif; Tufoi, Marius; Gillich, Nicoleta

doi:10.1088/1742-6596/628/1/012091

Cited by 7 publications

(5 citation statements)

References 11 publications

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“…The values of the normalized frequency shift [23] for sample 1 in each group, with respect to the rest of the samples of the same group, are presented in Figure 14. Due to the geometrical variations and high amplitude of vibrations, there is up to 33% frequency change in Group 1 for mode 1, while the other modes show a small frequency shift between the first and the rest of the samples.…”

Section: Normalized Frequency Shift Calculationsmentioning

confidence: 99%

Experimental and Numerical Simulation Study of the Vibration Properties of Thin Copper Films Bonded to FR4 Composite

Azam

Fragoso

2020

Applied Sciences

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Printed circuit boards constitute the basis of most electronic devices and are mainly fabricated of thin copper films bounded to fiber epoxy laminates, such as FR4. Vibrational stress can induce device failure, and hence, studies addressing their modal properties have important applications. In this paper, cantilever samples made of bare copper bounded to FR4 have been studied to analyze, for the first time, the vibration behavior of specimens with different aspect ratios, with and without central holes of different diameters. Natural frequencies and damping ratios were determined experimentally and analytically using a finite element method for four groups of samples with a very good correspondence between both methods. The fundamental resonance frequency of all the specimens was found to be less than 40 Hz and the influence of a central hole was not significant to affect the modal properties.

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Section: Normalized Frequency Shift Calculationsmentioning

confidence: 99%

Experimental and Numerical Simulation Study of the Vibration Properties of Thin Copper Films Bonded to FR4 Composite

Azam

Fragoso

2020

Applied Sciences

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“…Also, as stated by Negru et al [2015], transversal cracks in composite structures affect their stiffness as well as the natural frequency values. For a given crack, irrespective of its depth, the frequency drop ratio of any two transverse modes is similar (de Assis and ).…”

Section: Natural Frequency-based Methodsmentioning

confidence: 97%

On the use of Modal Test Data in Inverse Problems: Fundamentals and Applications

Gomes¹,

Carneiro²,

S.³

et al. 2022

Fundamental Concepts and Models for the Direct Problem

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In the past few decades, modal testing has become a major technology for determining, improving and optimizing dynamic characteristics of engineering structures in different fields, with emphasys (but not limited to) mechanical, civil, and aeronautical/aerospace engineering. One of the great advantages of using modal tests is related to their experimental practicality. This practical advantage leads to its strong use in inverse methods, or commonly known as inverse modal-based problems. An inverse problem based on modal parameters can be formulated basically using i) natural frequency, ii) damping factor or loss factor and iii) mode shapes. Other metrics can also be used from the composition of these 3 main responses, such as modal strain energy, inverse FRF and many others. Inverse modal-based identification through optimization algorithms are particularly emphasized. The methods discussed here are mainly elaborated by the evaluation of modal data due to the great potential of application. This chapter discusses the use of computational and intelligent techniques for parameter identification using modal responses. The content in this paper aims to help engineers and researchers find a starting point in developing a better solution to their specific structural problems, either by inverse methods, pattern recognition, or intelligent signal processing.

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“…Many researchers had detected shifts in the natural frequency when there was damage in the structure or material. Negru et al (2015) studied how transverse cracks in structures affect their stiffness as well as natural frequency. Ján Svoreň et al (2015) studied various methods to obtain the natural frequencies of a circular saw disk.…”

Section: Introductionmentioning

confidence: 99%

Study of variation in natural frequencies of bio-composites due to structural damage

Shah

Pandya

Street

2020

International Wood Products Journal

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The purpose here is to study the variation in the natural frequency of a material due to damage. Also, compare the shift in Natural Frequency that of a SYP-SP (Sweet Potato) bio-composite to a commercial SYP composite. Additionally, the motivation behind the study is to eventually provide biodegradable materials, as petroleum-based products being a finite resource and having more potential to harm the environment. The researcher obtained the Natural Frequencies by Experimental modal analysis using a cantilever beam vibration technique. The shift for the first three natural frequencies for damage induced SYP-SP composite was 10%, 8.6%, and 9.5% and for SYP-Commercial composite was 7.95%, 0.7%, and 0.9% respectively. The undamaged specimens of SYP-SP bio-composite and that of a commercial SYP composite showed behaviour almost on similar lines. Thus, stating the potential use of SYP-SP bio-composite for commercial applications like wood flooring, fencing, and other related applications.

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Natural frequency changes due to damage in composite beams

Cited by 7 publications

References 11 publications

Experimental and Numerical Simulation Study of the Vibration Properties of Thin Copper Films Bonded to FR4 Composite

Experimental and Numerical Simulation Study of the Vibration Properties of Thin Copper Films Bonded to FR4 Composite

On the use of Modal Test Data in Inverse Problems: Fundamentals and Applications

Study of variation in natural frequencies of bio-composites due to structural damage

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