Studies on the Stability of Pipes Conveying Fluid : (The Combined Effect of a Spring Support and a Lumped Mass)

The present paper deals with the combined effect of a spring support and a lumped mass on the stability of a tubular cantilever conveying fluid. The support and the mass are assumed to be attached to the cantilever at the same location. The validity of Galerkin's 8 term approximation is discussed from the view point of predominant eigenmodes in critical flutter configurations. It is shown that for particular combinations of spring stiffness and lumped mass there exists an instability region which jutts out from the main flutter domain. Both theory and experiment confirm that the instability in the region is of mild flutter type, not violent.