Abstract
This paper presents experimental techniques used in and results obtained during a series of experiments performed to investigate the free-vibration behavior of 15-in. base-diameter spherical and paraboloidal shell models of various geometric parameters and boundary conditions. The models were manufactured from polyvinyl-chloride (P.V.C.) sheets by a thermo-vacuum process using special molds and templates. To provide the necessary excitation power, a variable control amplitude/frequency audio oscillator was used to drive a loudspeaker which was mounted underneath the models.
A recently developed noncontact fiber-optics instrument, referred to as the “Fotonic Sensor”, was employed in determining the motion of the models. Thirty-two models of different configurations and boundary conditions were tested in the series. The natural frequencies were observed for all models, while the mode shapes associated with the first four-to-six resonant frequencies were mapped only for some of the models, using special scanning devices.
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Abbreviations
- E :
-
Young's modulus of elasticity
- f :
-
natural frequency of free vibration
- h :
-
thickness of shell model
- H :
-
rise of shell model
- m :
-
mass density of material
- r 0 :
-
base radius of shell model
- R :
-
radius of curvature of shell model
- w :
-
normal displacement
- ε:
-
strain
- θ:
-
circumferential angle
- ν:
-
Poisson's ratio
- ρ:
-
specific gravity of material
- σ:
-
stress
- ϕ:
-
meridional angle
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The results presented in this paper were obtained in the course of research sponsored by the National Research Council of Canada, Grant No. A-2736, and the Defence Research Board of Canada, Grant No. 6301-11.
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Glockner, P.G., Tawadros, K.Z. Experiments of free vibration of shells of revolution. Experimental Mechanics 13, 411–421 (1973). https://doi.org/10.1007/BF02324885
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DOI: https://doi.org/10.1007/BF02324885