Assessing the axial buckling load of a pressurized orthotropic cylindrical shell through vibration correlation technique

Robustness of Empirical Vibration Correlation Techniques for Predicting the Instability of Unstiffened Cylindrical Composite Shells in Axial Compression

“…The prediction accuracy was also found to generally improve when experimental data of f m vs. P for greater P / P b ratios were used, as expected. The VCT-predicted and experimental KDFs for the highest load levels used in each of the studies [ 21 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ] are presented in a parity plot in Figure 1 a. Specifically, for CFRP shells, the maximum loads in these VCT studies amounted to P / P b = 0.81…0.98 [ 21 , 25 , 26 , 27 , 28 ], whereas for metal shells, they were P / P b = 0.54…0.99 [ 26 , 30 , 31 ].…”

“…. 0.99 [26,30,31]. Further, a wide range of cylinder geometries, as characterized by the relative shell length parameter ω = H/ √ R•t [33], expressed via cylinder height H, radius R, and wall thickness t, has been covered in the tests, Figure 1b.…”

“…This VCT method has been applied for estimation of the buckling load in axial compression of CFRP shells of various lay-ups [ 21 , 23 , 25 , 26 , 27 , 28 ], including a variable-angle tow CFRP shell [ 28 ], as well as grid-stiffened glass/epoxy [ 29 ], composite lattice sandwich [ 22 ], stainless steel [ 26 ] and aluminum alloy [ 30 , 31 ] shells. Apart from a pure axial loading, the critical load for pressurized aluminum alloy shells [ 31 ] has also been studied. Notably, a numerical simulation of the experimental VCT procedure of shells, implementing either real measured imperfections or appropriate assumed imperfections in the shell model, has also produced encouraging results [ 32 ].…”

“…However, a sufficiently detailed characterization of shell imperfections may be overly complicated in industrial applications. The advantage of VCT is that only a relatively uncomplicated nondestructive mechanical test of a shell is required [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ] instead of a detailed inspection of different imperfections of the shell. However, the boundary conditions of the structural element have to be accurately recreated in the shell test.…”

Impact of Geometrical Imperfections on Estimation of Buckling and Limit Loads in a Silo Segment Using the Vibration Correlation Technique

“…Skukis et al [ 14 ] verified this method experimentally with a good result. Recent papers confirmed effectiveness of the modified VCT by conducting experimental and numerical analyses on cylindrical shells stiffened with lozenge grid cores [ 15 ], pressurised orthotropic shells with rectangular stiffeners [ 16 ], sandwich plates with iso-grid cores [ 17 ], composite unstiffened shells [ 18 ] and variable angle tow composite cylindrical shells [ 19 ].…”