Instability of Thin Walled Bars

Abstract

Instability of thin walled bars of variable, open cross sections is analyzed. A thin walled bar is treated as a special case of the membrane shell with the internal constraints (Vlasov's and Wagner's assumptions). The geometry of the bar is described by means of coordinates of the discrete points located on the midsurface of the bar. Principal coordinate system is assumed for the cross section. Large deformations of the cross section are analyzed in total Langrangian formulation. Prebuckling strains are assumed to be small and the Green‐Lagrange linearized tensor is used in strain analysis. The general, nonlinear formula for the strain tensor element