Browsing by Subject "Sloshing (Hydrodynamics)"
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Item Deterministic behavior of elevated water tanks under vertical motion(Texas Tech University, 1985-12) Gau, Jin-shyThe dynamic response of 3n elsstic structure carrying 3 rigid cylindrical tank partially filled with a liquid subjected to vertical sinusoidal harmonic excitation Is considered. The nonlinear response is determined by using an asymptotic expansion technique developed by Struble. Secular terms which give rise to parametric resonance conditions are identified. Four parametric resonance conditions are found to take place when the excitation frequency is in the neighborhood of twice the natural frequency of one of the normal modes, or close to the sum or difference of the normal mode frequencies of the system. The steady-state responses of the system are obtained for the first three parsmetric resonance conditions and show the occurrence of the jumps phenomenon at a certain critical excitation frequency. Under combination parametric resonance of difference type the method does not provide any steady state response.Item Experimental investigation of random parametric liquid sloshing(Texas Tech University, 1986-12) Heinrich, Randy ThomasThe dynamic response of the liquid free surface in a circular cylindrical tank subjected to a random parametric excitation is investigated experimentally. Two main objectives are considered in this study. The first is to resolve a contradiction observed in the literature of various methods used to predict the mean square stability. The second is to verify the results predicted by the non—Gaussian closure scheme. Experimental measurements are processed to estimate the response statistical parameters. These include the mean, mean square, and probability density functions for the first anti—symmetric and first symmetric sloshing modes. The tests are repeated for various excitation spectral density levels. The results confirm the jump phenomenon for the first anti—symmetric sloshing mode as predicted by the non—Gaussian closure scheme. The measured statistical parameters show some deviations from the predicted results. This disagreement is mainly attributed to the fact that the excitation is represented by a physical white noise process in the analytical model while it is a band—limited random process in the actual experimental tests.Item Response of a nonlinear two-degree-of-freedom system to a horizontal harmonic excitation(Texas Tech University, 1985-12) Li, WenlungAn elastic structure containing a fluid subjected to a horizontal sinusoidal excitation is investigated. The system is found to include cubic nonlinearities. The system response is determined by using the multiple scales asymptotic approximation method. The method predicts that primary resonances may occur when the excitation frequency, Ω is close to either the first mode natural frequency, ω1, or the second mode natural frequency, ω2. The system behavior under the fourth order internal resonance condition (ω2 ≈ 3ω1) is predicted. The system response under conditions of primary resonances (Ω ≈ω1 and Ω≈ω2), together with internal resonance is also considered. Other features, such as amplitude jump phenomenon and chaotic-like response have been observed. Two possible responses have been found when Ω is near ω2 = unlmodal response and autoparametric interaction response. The boundaries of these two motions are defined in the excitation amplitude - frequency plane. Moreover, the so called "static attractor" is also observed.Item Stationary response of liquid free surface under wide-band random parametric excitation(Texas Tech University, 1983-05) Soundararajan, AravamudhanThe stationary response of a liquid free surface in a partially filled cylindrical container, to a wide band random parametric excitation, is investigated. Two analytical approaches are employed. The first is the Gaussian closure scheme to truncate the infinite hierarchy moment equations obtained through the Fokker-Planck equation, and the second is the Stratonovich stochastic averaging approach. The validity of the two solutions is examined by comparing the two analytically predicted probability densities with the one obtained through experiments. The comparison reveals poor agreement with the Gaussian probability density. In contrast, the probability density derived by the averaging method agrees very well with the experimental density.