Study on free vibration response of a liquid retaining composite structure considering fluid?wall interaction

摘要

Free vibration response of composite side walls of liquid retaining tank is carried out in the present study using direct couplingmethod. Graphite-epoxy side walls are modelled using eight noded isoparametric element with five degrees of freedomper node. The fluid inside the reservoir is modelled with sixteen noded brick element. First-order shear deformation theory(FSDT) is employed to obtain the strain terms of the thin plate with proper shear correction factor. Plate and fluid are modelledseparately in Matlab environment and then coupled in a direct way to obtain the vibration response of the side wallsconsidering the effect of fluid–structure interaction (FSI). Influence of parametric variations in terms of ply angle, ply layers(number and thickness), stacking sequence, tank geometry and boundary conditions are considered and respective responsesare presented graphically with several numerical examples. Convective wave propagation is more predominant in the secondfrequency of the fluid; hence, the first three natural frequencies are studied in depth to represent the actual free vibrationresponse. Outcome of the present study shows that frequency values increase with increase in ply angle though symmetric45° 2 layered lamination shows peak values among all the cross-ply or angle-ply variations. Height of the tank wall is also aguiding factor for frequency as it increases up to a ratio (height/length) of 0.5. Variation in boundary conditions reveals thattank with all edges simply supported for both the side walls has maximum frequency. Effect of convective wave response isalso observed with the results associated with second frequency values. Mode shapes of the plate under different boundaryconditions are also presented at the end.