A comprehensive computer program, designated BIGBOSOR4, for analysis of the stress, stability and vibration of segmented, ring-stiffened, branched shells of revolution and prismatic shells and panels is described. The program performs large deflection axisymmetric stress analysis, small-deflection non-symmetric stress analysis, modal vibration analysis with axisymmetric nonlinear pre-buckling stress included, and buckling analysis with axisymmetric or non-symmetric pre-buckling stress.

One of the main advantages of BIGBOSOR4 is the provision for realistic engineering details such as eccentric load paths, internal supports, arbitrary branching conditions, and a library of wall constructions. The program is based on the finite difference energy method, which is very rapidly convergent with increasing numbers of nodal points. The discretization is one-dimensional: along the meridian of each segment of the possibly complex, branched shell of revolution. The variation of deformation in the circumferential coordinate direction is trigonometric. Because of the one-dimensional discretization the stiffness and load-geometric matrices are very narrowly banded. Therefore, solutions are obtained very rapidly, even for configurations with many, many shell segments. This makes BIGBOSOR4 particularly suitable for use in an optimization context. BIGBOSOR4 has been “hooked up” with GENOPT, a system of programs that can be used to optimize anything.

BIGBOSOR4 graphic showing non-axisymmetric load on rocket

Graphic from Structural Analysis Systems – Vol. 2, A. Nikuj-Lari, editor, Pergamon, 1986, “BOSOR4 – Program for stress, stability and vibration of complex, branched shells of revolution”, by David Bushnell, pp. 25-54.

Buckling mode of a non-axisymmetrically loaded rocket payload shroud: (a) Pressure distribution measured in a wind tunnel test; (b) Prebuckling beam-type deflection; (c) Non-axisymmetric buckling mode. Buckling is between the discrete rings and occurs with 13 circumferential waves.

For a gallery of the kind of problem that can be solved by BIGBOSOR4, see this slide show that is primarily composed of pictures taken from the long, illustrated abstracts of papers about BOSOR4 and results generated from executions of BOSOR4.

NOTE: BIGBOSOR4 supersedes BOSOR4. Input files for BOSOR4 are also valid for BIGBOSOR4. BIGBOSOR4 runs bigger problems than BOSOR4, problems with many more shell segments.

Abstracts and Papers

2012 NOTE: BOSOR4 is superseded by BIGBOSOR4, which permits many more shell segments. The papers listed above were written before BIGBOSOR4 existed. However, they also pertain to BIGBOSOR4. Input files for BOSOR4 are valid for BIGBOSOR4.

BIGBOSOR4 has capabilities that BOSOR4 does not have:

  1. BIGBOSOR4 will analyze “true” prismatic shells, that is, shells that are rigorously prismatic, not just toroidal shells of such a form as to simulate approximately the behavior of prismatic shells as described in the paper, Stress, Buckling, and Vibration of Prismatic Shells, David Bushnell, AIAA Journal, Vol. 9, No. 10, pp 2004 – 2010, 1971. In order to download details about this topic, click on:

    Prismatic Shell Models

  2. BIGBOSOR4 will analyze complicated shells of revolution supported by springs. In order to download details about this topic, click on:

    Shells Supported by Springs

BIGBOSOR4 subroutines produce Postscript files by means of which plots can be shown on a computer screen or hard copies can be obtained.