In this paper, a unified beam theory is developed and applied to study the buckling response of two types of functionally graded sandwich beams. In the first type (Type A), the sandwich beam has a hardcore whereas in the second type (Type B), the sandwich beam has a softcore. In both the type of beams, face sheets are made up of functionally graded material. The material properties of face shee...

The Letter by Deng et al. [1] presents an analytic theoretical description of matter-wave superradiance [2] which claims to go beyond previous theoretical frameworks. I show here that the theory presented in this Letter is not a description of superradiance per se, but rather an elegant perturbative description of a Raman amplifier far away from the superradiant threshold. As such, it merely is...

In this paper, the size dependent behavior of the gold micro-switches has been studied. This behavior becomes noticeable for a structure when the characteristic size such as thickness or diameter is close to its internal length-scale parameter. The size dependent effect is insignificant for the high ratio of the characteristic size to the length-scale parameter, which is the case of the silicon...

A finite element model based on the layerwise theory is developed for the analysis of transverse cracking in cross-ply laminated beams. The numerical model is developed using the layerwise theory of Reddy, and the von Kármán type nonlinear strain field is adopted to accommodate the moderately large rotations of the beam. The finite element beam model is verified by comparing the present numeric...

In this investigation Rayleigh-Ritz variational method has been applied to determine the least natural frequency coefficient for the title problem. Classical plate theory assumptions have been used to calculate strain energy and kinetic energy. Coordinate functions are combination of polynomials which satisfy boundary conditions at the outer boundary and trigonometric terms. In the second part ...

A Timoshenko beam equation with boundary feedback control is considered. By an abstract result on the Riesz basis generation for the discrete operators in the Hilbert spaces, we show that the closed-loop system is a Riesz system, that is, the sequence of generalized eigenvectors of the closed-loop system forms a Riesz basis in the state Hilbert space. 1. Introduction. The boundary feedback stab...

Is. ,•l•i, "B•k reflection ofultrasonic waves obliquely incident to a solid surface in water," Ipn. I. Appl. Phys. 2, 198 (1963). 20. l. Diachok and W. G. Mayer, "Conical reflection of ultrasound from a liquid-solid interface," J. Acoust. Soc. Am. 47, 1:55-157 (1970). 3W. G. Neubauer, in Elastic Wave Scattering and Propagation, edited by V. K. Varadan and V. V. Varadan (Ann Arbor Science, Ann A...

Compared to bulk waves, Rayleigh waves can propagate much longer distances with lower signal attenuation levels, which are nominally proportional to r / 1 for a given frequency (r=distance). In addition to the small attenuation, Rayleigh waves are also non-dispersive and sensitive to surface-breaking defects. The surface penetration depth of Rayleigh waves is also approximately one wavelength, ...

In this paper, a size-dependent formulation for the Bernoulli-Euler beam is developed based on a new model of couple stress theory presented by Hadjesfandiari and Dargush. The constitutive equation obtained in this new model, consists of only one length scale parameter that is capable of capturing the micro-structural size effect in predicting the mechanical behavior of the structure. Having on...