Stacking sequence optimization and modeling of laminated composite plates for free vibration
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Date
2018-01
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Izmir Institute of Technology
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Green Open Access
No
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No
Abstract
Composite materials, especially fiber reinforced composites, have been
extensively used in various engineering fields such as automotive, aerospace, aircrafts,
defense, marine and so on due to having their high specific strength to weight and
stiffness to weight ratios. In these last years, vibration problem has become more and
more important in the structures where thin plates are used. Therefore, free vibration
characteristics of composite structures under the influence of dynamic forces should be
determined in the design process. Accordingly, in this thesis, optimum designs, which
maximize the natural frequencies of laminated composite plate, are investigated by
using hybrid algorithm combining the genetic algorithm (GA) and generalized pattern
search algorihm (GPSA). Composite plates made of graphite/epoxy have been
considered and assumed to be symmetric with continuous fiber angles in the laminate
sequences. The natural frequency of plates is obtained bu using the Rayleigh Ritz
method analytically. Free vibration equation is taken as objective function and fiber
orientation angles are chosen as design variables. The natural frequency is maximized
for various boundary conditions, aspect ratios, number of ply and material properties.
The optimum designs obtained are verified by finite element method, and mode shapes
of laminated composite plates are presented. A comparison between continuous and
conventional (laminate in which the orientation angles are limited to the conventional
orientations) designs is performed in order to show the reliability of continuous plates.
As a results, it is observed that material properties, boundary conditions and dimensions
of composite plates play important role on vibration behavior of composite plates. On
the other hand, the natural frequencies and the optimum fiber oriantation angles are not
affected from the change of number of plies.
Description
Thesis (Master)--Izmir Institute of Technology, Mechanical Engineering, Izmir, 2018
Full text release delayed at author's request until 2020.01.31
Includes bibliographical references (leaves: 81-83)
Text in English; Abstract: Turkish and English
Full text release delayed at author's request until 2020.01.31
Includes bibliographical references (leaves: 81-83)
Text in English; Abstract: Turkish and English
Keywords
Laminated composite plates, Vibration analysis, Optimization, Hybrid algorithm, Composite materials, Mechanical Engineering, Makine Mühendisliği