Makine Mühendisliği Bölümü Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.11779/1944
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Book Part Citation - Scopus: 319 - Identification of the Elastic and Damping Properties of Jute and Luffa Fiber-Reinforced Biocomposites(Elsevier, 2022) Genç, Garip; Saygılı, Yusuf; Körük, Hasan; Şanlıtürk, Yusuf Kenan; Sanliturk, Kenan Y.Although there are many studies in the literature on the static mechanical properties of biomaterials such as tensile strength, the dynamic mechanical properties of biomaterials such as modal loss factors have not been investigated in detail. In this study, the Young’s moduli and damping (or loss factors) of some jute and luffa fiber-reinforced biocomposites are investigated. The effects of fiber/resin ratio and thickness on the mechanical properties of the jute and luffa composites are identified via an experimental approach. For this purpose, acoustic and structural frequency response functions of some homogeneous and hybrid jute and luffa composite plates with different fiber/resin ratios and thicknesses are measured. By analyzing the measured frequency response functions using the circle-fit method, the modal frequencies and loss factors of the homogeneous and hybrid composite plates are determined. By assuming that the homogeneous plates are isotropic, the same plates are modeled using the finite element method, and by comparing the experimental and theoretical natural frequencies, the elastic properties of the homogeneous plates are determined. In addition, the same homogeneous plates are modeled by considering an anisotropic material model, and the associated material properties are determined. By using the identified material properties, the finite element models of the hybrid composite plates are developed, and by comparing their experimental and theoretical natural frequencies, the identified elastic material properties are evaluated and validated.Article Citation - WoS: 9Citation - Scopus: 11Development of an Equivalent Shell Finite Element for Modelling Damped Multi-Layered Composite Structures(Elsevier, 2020) Şanlıtürk, Kenan Y.; Özer, Mehmet Sait; Körük, HasanA new equivalent shell finite element (FE) for modelling damped multi-layered structures is presented in this study. The method used for developing the new FE for such structures is based on the idea that the strain energy of the equivalent single-layer FE must be equal to the sum of the strain energies of individual layers. The so-called energy coefficients are defined for this purpose for the extensional, bending and shear deformations of the composite structure. These coefficients are then determined and used as correction multipliers during stacking the elemental matrices of individual layers. Two approaches, based on second-order strain or stress distribution assumption through the composite thickness, are investigated for deriving the shear energy coefficients. The damping capability of the FE developed here originates from using complex Young's modulus to define the material properties of individual layers. The resulting equivalent single-layer shell element with four nodes has six degrees-of-freedom per node. The accuracy, advantages and limitations of the composite FE developed in this work are investigated using experimental as well as theoretical results. In the light of the finding of these investigations, further enhancement in the formulation is made by also utilising a new shear correction factor for the individual layers in the equivalent shell element. Final results for free- and constrained-layered structures confirm that the equivalent shell FE developed here can be used effectively for the prediction of the modal properties of damped multi-layered structures.Conference Object Laser-Generated Surface Acoustic Wave-Based Study and Detection of Surface Cracks(Int. Sc. & Tech. Conf. Beam technologies & Laser Applications, 2015) Chen, Kun; Fu, Xing; Li, Tingting; Dorantes-Gonzalez, Dante Jorge; Li, Yanning; Wu, SenMonitoring cracks to check the integrity of engineering materials by Non- Destructive Testing (NDT) in industry is significant in industry. And within the NDT techniques, Laser-Generated Surface Acoustic Wave technique (LSAW) has shown to be a promising technique. To further develop non-contact and accurate testing strengths of this method, models for analyzing the generation, propagation and tracking of surface acoustic waves (SAW’s) changes in S45C steel samples with distributed cracks are developed by using Finite Element Method (FEM). Time and frequency domain analyses are used to process the acoustic wave signals after the interaction with cracks. The simulation results and preliminary analyses reveal the good potential LSAW’s have to monitor cracks. First results in developing an experimental setup for crack detection are also provided.