Dynamic properties of the Shear Thickening Fluid (STF) are studied. Two series of tests by the Split Hopkinson Pressure Bar method were carried out to determine the dynamic bulk and shear properties of STF. The hypothesis about the possibility to describe STF behavior by a Newtonian fluid model in the characteristic range of strain rates is confirmed. A simplified mathematical model of the STF is then formulated for the use in computer simulation of ballistic impact tests of multilayered composite protective shells. The effectiveness of the STF impregnation for improvement of ballistic impact characteristics of Kevlar woven fabrics is confirmed. It is concluded that the role of the contact conditions between STF and Kevlar basis in the process of increasing the energy absorption capacity of Kevlar-STF barrier is significant, noting that the mechanism of contact interaction between STF and Kevlar basis can be described by viscous friction law, i.e., the STF behaves almost as a rigid body during the interactions with the solids, while it normally behaves as a fluid. It is also established that the STF impregnation of protective shells with titanium framework not only increases the absorption capacity of the whole package but also reduces the deflection of the metal base.

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Blade flutter of modern gas-turbine engines is one of the main issues that engine designers have to face. The most used numerical method that is employed for flutter prediction is the energy method. Although a lot of papers are devoted to the analysis of different blade wheels, this method was rarely validated by experiments. Typical mesh size, time step, and various modeling approaches that guarantee reliable flutter prediction are not commonly known, whereas some examples show that predictions obtained through nonvalidated codes can be inaccurate. In this paper, we describe our implementation of the energy method. Analysis of convergence and sensitivity to various modeling abstractions are carefully investigated. Numerical results are verified by compressor and full engine flutter test data. It is shown that the prediction of flutter onset is rather reliable so that the modeling approaches presented in this paper can be used by other researchers for the flutter analysis of industrial compressor blades. Nomenclature f = natural frequency m = number of nodal diameters N = number of blades n = rotor speed W = work done by the unsteady pressure over one cycle of blade oscillation α = inlet angle of attack φ = 2π m∕N, interblade phase shift ω = 2πf, circular frequency

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