First, you define material data, panel dimensions and boundary conditions. Options to import the corresponding data from RSTAB are available. Then, you define the boundary stresses for each load case, either by manual input or import from RSTAB.

The stiffeners are modeled as spatially effective surface elements eccentrically connected to the plate. Therefore, it is not necessary to take into account the stiffener's eccentricities by effective widths. The stiffeners’ bending, shear, strain and St. Venant stiffness as well as the Bredt stiffness for closed stiffeners is determined automatically when using a real 3D model.

The analyses are carried out successively by calculating the eigenvalues of the ideal buckling values for the individual stress conditions (exclusive effect of s_x, s_y, t) and the buckling value for the simultaneous effectiveness of all stress components.

To determine the buckling behavior which is similar to the behavior of a buckling member, PLATE-BUCKLING calculates the eigenvalues of the ideal c/t parts' buckling values with longitudinal panel sides assumed to be free.

Then, the module determines the slenderness and the reduction factors according to DIN 18800, part 3, table 1. Finally, the analysis is performed in accordance with DIN 18800 part 3, eq. (9), (10) or (14). 

The buckling panel is discretized in finite quadrilateral or, if necessary, triangular elements. Each node of an element has six degrees of freedom.

The bending component of the triangular element is based on the LYNN-DHILLON-Element (2nd Conf. Matrix Meth. JAPAN – USA, Tokyo) according to the bending theory described by Mindlin. The membrane component, however, is based on the BERGAN-FELIPPA-Element. The quadrilateral elements consist of four triangular elements and the inner node is eliminated.

The results are displayed with references to DIN 18800. In addition, the module represents the calculation results separately for the occurance of a single edge load and for the simultaneous occurance of all boundary loads.

In case of several load cases, PLATE-BUCKLING displays the governing load case separately. Thus, a time-consuming comparison of calculation data is not necessary. 

The results table showing the buckling load factors displays for all load cases the actions resulting from s_x, t and s_y for all buckling modes. The values s_kx and s_ky represent the influence of the buckling behavior similar to the one of buckling members. 

All buckling modes as well as loadings of the buckling panel can be visualized in the graphic window. Use this results display to check the buckling modes or load data quickly. Finally, you can take advantage of the animation option used to show the modes in motion, which may help you to understand the buckling behavior of stiffened plates in particular.

Finally, you can export all tables to MS Excel, OpenOffice.org Calc or in a CSV file without any problems. All specifications required for the export are defined in a special transfer menu.