From: David Bushnell and Charles Rankin, "Use of GENOPT and BIGBOSOR4 to obtain optimum designs of multi-walled inflatable spherical and cylindrical vacuum chambers", AIAA Paper 2012-1446, 53rd AIAA Structures, Dynamics and Materials Conference, Honolulu, Hawaii, April 2012.

This is Fig. 65 from the 2012 GENOPT paper. This slide shows GENERAL bifurcation buckling of the optimized cylindrical balloon with 40 modules over 90 degrees of circumference and with truss-like webs. This GENERAL buckling mode is analogous to the GENERAL buckling mode displayed two slides ago for the cylindrical balloon with 15 modules over 90 degrees of circumference.

There are 31 nodal points in each segment of the model, which is the nodal point density specified in the “balloon” software, SUBROUTINE BOSDEC (NODSEG = 31) for optimization.

In this case BIGBOSOR4 produces an eigenvector that has a significant component of local spurious “zig-zag” buckling modal displacement.

The question arises: “Does the presence of the spurious ‘zig-zag’ component of buckling modal displacement significantly affect the critical buckling load factor (eigenvalue) predicted by BIGBOSOR4?” The answer from the predictions listed in Tables 21 and 22 of the 2012 GENOPT paper appears to be: “no”.

For viewing figures and tables referred to here but not shown here, please download the 2012 GENOPT paper from this website

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