PSI - Issue 36

O.L. Derkach et al. / Procedia Structural Integrity 36 (2022) 71–78 O.L. Derkach et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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2. The mechanisms of influence of the damage parameters (notch depth and its location over the beam length) and the degree of anisotropy of the elastic properties in composite material on the principal frequency variation of flexural vibrations of the cantilever beam were determined: - the most significant decrease of the vibration frequency independently of the notch depth is the fibers ’ orientation along the beam axis, whereas the smallest decrease – at 45 deg to it. The nature of the dependencies of the principal frequency variation of flexural vibrations is determined from the relation between shear moduli of the matrix and fibers, which can implies the influence of the shear deformation on the variation of the principal frequency of vibrations of the damaged composite beam; - in the notch location near the beam clamped end, independently of its depth and angle of the fibers, the principal frequency of flexural vibrations of the damaged beam reduces as compared with that one for the intact beam, while the reduction level at the specified notch depth increases with an increase of the reinforcement angle; - there is such notch location over the beam length for the specified depth and width, the so-called transition point, at which the natural frequency of vibrations of the damaged and intact beams is the same independent of the fibers ’ orientation, which indicates the identical damage effect on both the variation of the stiffness and inertia properties of the beam. The transition point position depends on the notch depth and angle of the fibers. With the subsequent distance of the notch from the transition point to the free end, the principal frequency of vibrations of the damaged beam increases as compared with that one for the intact beam. Acknowledgements The paper was prepared within the funding of the NAS of Ukraine 2021-2022 for the scientific project “Development of Procedure of the Determina tion of the Influence of the Damage Parameters on the Modal Characteristics of the Composite Beam Elements of the Layered Structure” by the group of young scientists of the NAS of Ukraine (grant agreement No 05/01-2021(3)). References Cawley, P., Adams, R.D., 1979. A vibration technique for non-destructive testing of fibre composite structures. J. Composite Materials 13, 161 – 175. Derkach, O.L., Zinkovskyi, A.P., Savchenko, O.V., 2020. Active damping of nonstationary vibrations of a three-layer electro-viscoelastic composite plate. Strength of Materials 52, 876 – 888. Ghoneam, S.M., 1995. Dynamic analysis of open cracked laminated composite beams. Composite Structures 32, 3 – 11. Kim, K., Choe, K., Kim, S., Wang, Q., 2019. A modeling method for vibration analysis of cracked laminated composite beam of uniform rectangular cross-section with arbitrary boundary condition. Composite Structures 208, 127 – 140. Kisa, M., 2004. Free vibration analysis of a cantilever composite beam with multiple cracks. Composite Science and Technology 64, 1391 – 1402. Krawczuk, M., Ostachowicz, W.M., 1995. Modeling and vibration analysis of a cantilever composite beam with a transverse open crack. Journal of Sound and Vibration 183, 69 – 89. Kruts, V., Zinkovskii, A., Savchenko, K., Onyshchenko, Y., 2019. Finite element analysis of the open crack influence on the compressor blade natural frequencies, 26th International Congress on Sound and Vibration (ICSV26), Montreal, Canada, 7-11 July, paper #224. Manivasagam, S., Chandrasekaran K., 1992. Characterization of damage progression in layered composites, Journal of Sound and Vibration 152, 177 – 179. Song, O., Ha, T.-W., Librescu, L., 2003. Dynamics of anisotropic composite cantilevers weakened by multiple transverse open cracks. Engineering Fracture Mechanics 70, 105 – 123. Yershov, R., Savchenko, O., Zinkovskii, A., Derkach, O., 2020. Electronic system for calculation-experimental determination of the modal and damping characteristics of active viscoelastic beams, 40th International Conference on Electronics and Nanotechnology (ELNANO), Kyiv, 858 – 863. Zinkovskii, A.P., Tokar', I.G., Kruts, V.A., 2015. Influence of the local surface damage parameters on the natural frequencies of vibration of structural elements. Strength of Materials 47, 221 – 226. Zinkovskii, A.P., Tokar', I.G., 2018. Influence of local surface damage of the natural frequencies of the higher modes of flexural vibration of cantilever rods. Strength of Materials 50, 557 – 564.