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Structural Engineering and Mechanics
  Volume 16, Number 2, August 2003, pages 195-217
DOI: http://dx.doi.org/10.12989/sem.2003.16.2.195
 


Effect of boundary conditions on the stability of beams under conservative and non-conservative forces
A. Marzani and E. Viola

 
Abstract
    This paper, which is an extension of a previous work by Viola et al. (2002), deals with the dynamic stability of beams under a triangularly distributed sub-tangential forces when the effect of an elastically restrained end is taken into account. The sub-tangential forces can be realised by a combination of axial and tangential follower forces, that are conservative and non-conservative forces, respectively. The studied beams become unstable in the form of either flutter or divergence, depending on the degree of non-conservativeness of the distributed sub-tangential forces and the stiffness of the elastically restrained end. A non-conservative parameter a is introduced to provide all possible combinations of these forces. Problems of this kind are usually, at least in the first approximation, reduced to the analysis of beams according to the Bernoulli-Euler theory if shear deformability and rotational inertia are negligible. The equation governing the system may be derived from the extended form of Hamilton\'s principle. The stability maps will be obtained from the eigenvalue analysis in order to define the divergence and flutter domain. The passage from divergence to flutter is associated with a noticeable lowering of the critical load. A number of particular cases can be immediately recovered.
 
Key Words
    dynamic instability; non-conservativeness; sub-tangential forces; flutter and divergence; elastically restrained end.
 
Address
Department of Structures, University of Calabria, via Pietro Bucci, Arcavacata di Rende Cosenza, Italy
Department of Civil Engineering, DISTART, University of Bologna, Viale Risorgimento 2, Bologna, Italy
 

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