Suppose I have a plate 60 (a) x 40 (b) dimension. Is all the buckling calculation based on this dimesnion of a and b or does Hypersizer calculate a buckling critical length and if yes how is it calculated. Help is much appreciated. Thanks.

If the loads are uniform, then HyperSizer will perform all panel buckling calculations based on these dimensions. It does not attempt to calculate the critical buckling length. I assume by critical buckling length, you are saying that given a fixed load, calculate the critical length at which the panel will buckle. HyperSizer does not take that approach. Rather it assumes a fixed buckling length and calculates the eigenvalue from which the critical buckling load is found.

If the loads are non-uniform, where part of the panel is in tension and part is in compression, HyperSizer adjusts the buckling length so that only the compressive part of the panel is included in the buckling wave. For details, see this post:

http://hypersizer.com/faq/index.php?topic=88.0