Linearized Buckling Analysis
A linearized buckling analysis can be used to estimate the critical load at which a structure becomes unstable. This is a predefined study type that consists of two study steps: An initial step in which a unit load is applied to the structure, and a second step in which an eigenvalue problem is solved for the critical buckling load.
COMSOL reports a critical load factor, λ,which is the multiplier to the initial load at which the structure becomes unstable. The corresponding eigenmode is the shape of the structure in its buckled state.
The level of the initial load used is immaterial since a linear problem is solved. If the initial load actually was larger than the buckling load, then the critical value of λ is smaller than 1. It is also possible that the computed value of λ is negative. This signifies that a reversed load will give the critical case.
When performing a linearized buckling study, it is possible to discriminate between live and dead loads, where the former are the ones with respect to which the critical load factor is computed, and the latter are assumed to be constant. In this case, two different basic load cases need to be solved before the eigenvalue solution.
The buckling computed buckling modes can be used to provide an initial imperfection for a subsequent nonlinear buckling analysis,
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For more details about how to model buckling, see Buckling Analysis.
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The numerical formulation is described in the section Linear Buckling in the Structural Mechanics Theory chapter.
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Settings for the solvers are described in Studies and Solvers, Linear Buckling, and Buckling Imperfection in the COMSOL Multiphysics Reference Manual.
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Bracket — Linear Buckling Analysis: Application Library path Structural_Mechanics_Module/Tutorials/bracket_linear_buckling
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Buckling Analysis of a Truss Tower: Application Library path Structural_Mechanics_Module/Buckling_and_Wrinkling/truss_tower_buckling