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A finite element method is developed and validated for the estimation of loss factors of a viscoelastically damped plate. Viscoelastic layer is used as constrained layer and is sandwiched between an aluminum base plate and a constraining layer. Frequency-dependent material properties are used for the viscoelastic material in the finite element model. The derived dynamic equations of motion are used to carry out harmonic analysis to determine the natural frequencies and loss factors of sandwich plate and validated with experimental results for cantilever boundary condition. The validated finite element model is then used to estimate the loss factors of sandwich plate with various boundary conditions and different thicknesses of constraining and constrained layer for a given base plate thickness. The results show that the loss factor is maximum for a constraining layer to sandwich plate thickness ratio of 0.40–0.45 and is independent of boundary condition. The loss factor increases with increase in thickness of the viscoelastic layer. The loss factor increases for higher mode for all boundary conditions. [ABSTRACT FROM AUTHOR]

The lateral buckling analysis of cold-formed thin walled beams subjected to pure bending moments has been performed. The critical buckling loads are estimated based an optimization criteria. The estimated critical buckling stresses are compared with the published results, they show excellent agreement. The effect of the beam length, radius and thickness of the flanges and the length of the extended open flanges, on the critical buckling stresses have been studied for several combinations of the geometric parameters of the beam. Among the three beams, the critical buckling moments for the beam with the extended open flanges are found to be the maximum. However, considering the material and manufacturing costs, beams with rounded cross section are efficient in resisting the buckling loads. [ABSTRACT FROM AUTHOR]

Abstract: In this study, response of a flight vehicle component to rocket noise is considered. Tuned mass dampers, hitherto used in low frequency excitation, have been utilized to attenuate high frequency, broad band excitations. Modally tuned dampers have been investigated for a variety of input excitations. Modal dampers exhibit significant attenuation of all input signals. [Copyright &y& Elsevier]

We present the pre and post buckling analysis of stiffened composite panels based on the finite element models. Individual buckling studies are conducted on the stiffened composite panel madeup of woven fabric CFC/epoxy, E-glass/epoxy and the Kevlar/epoxy composites. Straight, T shaped and I shaped stiffeners are considered to stiffen the panel. The panel is fabricated with 8 layers and the stiffeners are madeup of 16 layers, of equal thickness arranged in different orientations. The panel is subjected to a uniform axial compression load of 10 kN. The distribution of the buckling stresses and the buckling loads with different panel and stiffener combinations are estimated for three different layup sequences. The variation of the buckling stresses and the buckling loads from the numerical model are compared with the experiment. The results are in excellent agreement. [ABSTRACT FROM AUTHOR]