On some recent developments of the frequency response and damping capabilities of the VAST finite element program

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On some recent developments of the frequency response and damping capabilities of the VAST finite element program

Lei Jiang / Chernuka, M.W. / Stredulinsky, D.

This paper presents some recent developments in the VAST finite element program suite to provide a capability for the analysis and design of vibration damping systems including viscoelastic materials, i.e. elastomers, as utilized in ship machinery vibration isolation system. In the first part of the paper, we discuss a recent enhancement of the direct frequency response analysis module in VAST, which is able to handle frequency-dependent, complex stiffness characteristics. The system loss factor, an important indicator of the effectiveness of vibration damping, is estimated using the strain energy weighted sum of the material loss factors. The second part of this paper deals with a simplified, finite element analysis (FEA) based procedure for optimal design of viscoelastically damped structures. This procedure uses the results of a sequence of VAST real constant coefficient eigenvalue analyses to predict the natural frequencies and system loss factor of damped structures with user specified damping materials and operating temperatures. From a graphical comparison of the system loss factors corresponding to various damping materials, the optimal one can be identified to achieve the best performance of a vibration damping system. The effectiveness of the VAST direct frequency response analysis capability and the simplified optimal design procedure has been verified by numerical examples.