Plastic buckling of circular tubes under axial compression—part II: Analysis

Liner wrinkling and collapse of girth-welded bi-material pipe under bending

“…In our study of lined pipe free of the constraining effect of welds [14][15][16], wrinkling and collapse were established for liner imperfections combining an axisymmetric mode and a shell-type mode with m circumferential waves as follows: Here is a characteristic wavelength often taken to correspond to the axisymmetric buckling mode of the shell under axial compression (e.g., see [21][22][23]) and {ω o , ω m } are amplitudes normalized by t L . It was demonstrated that the collapse curvature of the liner is significantly depended on both imperfection amplitudes and much less on m. Furthermore, comparison of collapse curvatures calculated using the actual buckling mode and imperfections like the one in Eq.…”

“…On the compressed side the separated liner sector develops periodic axial wrinkles similar to those seen in bending of a single pipe (e.g., see [17][18][19][20][21]). As is common to plastic buckling of shells, wrinkling is followed by a second instability that leads to catastrophic collapse of the liner in a diamond-type buckling mode (e.g., see [20][21][22][23]). The onset of liner wrinkling has been recently established by the authors through a plastic bifurcation check based on deformation theory of plasticity [16] akin to that of single tubes under bending of Ju and Kyriakides [17].…”

Strain ratcheting of steel tubulars with a rectangular defect under axial cycling: A numerical modeling

“…Bardi and Kyriakides [5,6] presented the results of an experimental study on stainless steel specimens with diameter-to-thickness ratios of 23 to 52. The evolution of wrinkles during the testing was monitored using a special surface-scanning device.…”

The torsional buckling of a cruciform column under compressive load with a vertex plasticity model

“…For buckling of circular tubes, Bardi et al (2006), Corona et al (2006) used the incremental moduli derived from the deformation theory as a linear comparison solid in the sense of Hill (1958) for computation of the buckling load under compressive and bending loads, respectively. The plastic buckling of different shell structures has been compared by Bushnell (1982).…”

“…However, for the secondary path, the according flow theory has to be used that relies upon artificial imperfections for triggering (Hutchinson and Budiansky, 1976). The amplitude of such imperfections is not a given geometric property but must be treated as an additional parameter that needs to be identified appropriately (Bardi et al, 2006;Corona et al, 2006).…”