Mixed formulation in Koiter analysis of thin-walled beams Original Research Article

The paper extends the asymptotic mixed formulation proposed in (G. Garcea, G. Salerno, Sanitizing of locking in Koiter perturbation analysis through mixed formulation, Fourth World Congress on Computational Mechanics, Buenos Aires, Argentina, 1988; G. Garcea, G. Salerno, R. Casciaro, Comput. Methods. Appl. Mech. Engrg. 180 (1–2) (1999) 137–167) to structures composed of an assemblage of flat slender elastic panels. The same type of structure has already been investigated in (A.D. Lanzo, G. Garcea, R. Casciaro, Int. J. Numer. Methods Engrg. 38 (1995) 2325–2345; A.D. Lanzo, G. Garcea, Int. J. Numer. Methods Engrg. 39 (1996) 3007–3031) with a compatible formulation and using the usual hypothesis of negligible precritical rotations in order to avoid the extrapolation locking (see also (G. Garcea, G.A. Trunfio, R. Casciaro, Comput. Methods. Appl. Mech. Engrg. 165 (1–4) (1998) 137–167) produced by the high axial to flexural stiffness ratio of the panels.