FEM-based approach for the stability design of thin-walled members by using cFSM base functions

摘要

This paper presents a new design approach for the stabilitydesign of thin-walled members. The proposed approach is basedon the buckling modes and critical forces/moments determinedby a linear buckling analysis performed on a regular shell finiteelement model. A fully automatic buckling mode identificationtechnique is applied, by using the modal base functions of thenewly proposed constrained finite strip method, where the vari-ous buckling types are separated by clearly defined mechanical criteria. The paper briefly summarizes the determination ofmodal base functions which then are used to approximate fi-nite element displacement functions (i.e., buckling modes). Themode identification method provides the lowest critical values(forces or moments) to all the three characteristic bucklingtypes: global, distortional and local, on the basis of which thebuckling resistance can be calculated by using the design formu-lae of the direct strength method. The proposed new approach,which is potentially more general than any of the existing de-sign approaches, is demonstrated on Z columns and beams withsimple loading and boundary conditions. Critical values as wellas resistances are calculated for some selected cases, the resultsare compared to those of another design method. The compar-isons prove the applicability of the proposed procedure. Furtherresearch is necessary to extend the proposal for more generaland more complex practical cases.