INTERACTION OF ELASTIC CONTAINER BOTTOM WITHFREE SURFACE OF A VISCOUS LIQUID IN A CYLINDRICAL CONTAINER

摘要

In modern space technology thin and light structures are for weight reasons of great importance. The high flexibility and low frequencies of the structural system leads to strong interactions with the liquid contained inside the system, as well as the control system. For such a reason the coupled hydroelastic frequencies of an incompressible and viscous liquid was investigated for a cylindrical container with an elastic bottom and a free liquid surface. It was found that viscosity decreases the coupled frequencies in the lower range of filling heights in comparison to frictionless liquid. In addition a new phenomenon appears, exhibiting for certain liquid height ranges only aperiodic motion, indicating that the liquid cannot oscillate in these domains. The magnitude of these ranges depend on the parameters of flexural rigidity of the container bottom, on the Ohnesorge number and the Bondnumber. With increasing angular and radial- mode number these aperiodic ranges decrease. It also could be shown that higher modes exhibit larger damping. Strong coupling of structure and free liquid surface occurs at low liquid heights.