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Amit Tyagi ¹, M. K. Ghosh ¹

Affiliations
1 Department of Mechanical Engineering, Institute of Technology, Banaras Hindu University, Varanasi-221005, IN

Abstract

In this work, transverse vibration of a thin rectangular plate with bonded high density and high modulus patch has been undertaken with simply supported boundary conditions at its edges. Plate material properties, patch thickness and patch area influence the transverse vibration of the host plate. Therefore, these effects must be accounted to correctly determine the natural frequencies of the plate in transverse vibration. The equation of motion for transverse vibration of the plate has been derived by taking into account of the patch material elasticity in the moment and force equations. The displacement function of the transverse vibration has been represented by a double Fourier series to solve the equation of motion for a composite plate with bonded elastic patch. Influence of dimensionless material and geometry parameters on the natural frequencies of the composite plate have been investigated. For material parameters, the flexural rigidity ratio and density ratio of the patch and the host plate have been considered. For geometrical parameters, area ratio and thickness ratio of the patch and the host plate have been considered. The location of the bonded elastic patch has been offset to study the influence of geometry on the modal frequencies. It has been found that these parameters significantly influence the modal frequencies. The results have shown that the shift in the fundamental mode frequency for the case of a central patch is larger than that of the offset patch. For a given area of the patch, the modal frequencies first increase and then decrease for an increase in the patch thickness.

Keywords

Transverse Vibration, Bonded Elastic Patch, Modal Frequency, Thin Plates.

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Amit Tyagi ¹, M. K. Ghosh ¹

Affiliations
1 Department of Mechanical Engineering, Institute of Technology, Banaras Hindu University, Varanasi- 221005, IN

Abstract

Present problem deals with a rectangular plate with a PZT patch bonded to it. The plate is considered to be simply supported at its edges. Since PZT possess electromechanical properties, electrical properties along with mechanical properties are considered while deriving the equations of motion for transverse vibration of the plate with patch. The primary focus in this paper is how these electrical properties affect the plate behaviour in terms of transverse vibration frequencies. Transverse displacement has been represented by a double Fourier series. Open circuit boundary condition has been applied to the PZT patch. Results have been obtained for a plate covered fully by the patch and also for a plate covered partially by the patch. It has been found in the present investigation that electrical properties affect modal frequencies significantly.

Keywords

Modal Analysis, Transverse Vibrations, Thin Plates, Piezoelectric, Electromechanical.

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J. K. De ¹, A. K. Roy Mahato ², M. K. Ghosh ¹

Affiliations
1 Zoological Survey of India, M-Block, New Alipore, Kolkata-700053, IN
2 Gujarat Institute of Desert Ecology, Bhuj, Kachchh-370001, Gujarat, IN

Abstract

Barasingha is one of the large size deer belonging to the family Cervidae wit h characteristic highly branched antler and residing in a marshy habitat, so called swamp deer (Jerdon, 1874; Blanford, 1888-91; Lydekker, 1898, Bhadian, 1934; Pocock, 1943; Schaller, 1967; Krishnan, 1972; Prater, 1971). Brander (1923) mentioned two races of barasingha north-eastern and central Indian races according to their living in two different type of habitat.

Keywords

Barasingha, Age-Sex Ratio, Population, Conservation, Dudhwa National Park.

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J. P. Srivastava ¹, M. K. Ghosh ¹

Affiliations
1 Zoological Survey of India, M-Block, New Alipore, Kolkata-700053, IN

Abstract

The two species of the genus Cynopterus Cuvier viz. Cynopterus sphinx and Cynopterus brachyotis are known to occur in Indian Territory, and are widely distributed in different parts of the country. Cynopterus sphinx has one subspecies, the nominate one. The subspecies of brachyotis occurring in India are angulatus, brachysoma, ceylonensis and scherzeri, Ellerman & Morrison Scott (1966), however. Hill and Thonglongya (1972) found angulatus more similar to sphinx and regarded it as a subspecies of sphinx on the basis of its external and cranial measurements being closer to sphinx.

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