Closed-Form Approximate Solutions for the Local Buckling Behavior of Composite Laminated Beams Based on Third-Order Shear Deformation Theory

This paper presents approximate closed-form analytical methods for the assessment of the local buckling behaviour (i.e. buckling of flanges and webs) of shear-deformable composite laminated beams. The analysis approach relies on the discrete plate method, i.e. the buckling analysis of flanges and webs modelled as separate plates that are elastically clamped at those edges where the adjacent section members are located. We perform these local buckling analyses within the framework of third-order shear deformation theory (short: TSDT) by Reddy (Mechanics of Laminated Composite Plates and Shells, 2004, [1]) and compare the results to analysis approaches that we established using classical laminated plate theory (CLPT) and first-order shear deformation theory (FSDT). The buckling analysis uses simple shape functions for the displacements and rotation angles and enables closed-form solutions based on the principle of minimum elastic potential of the buckled plates. The results show that the approximate analysis approach work with very satisfying accuracy despite its rather simple and straightforward nature and thus is especially suited for all practical applications where computational time and effort are crucial factors.