NOVA-2S, A Stiffened Panel Extension of the NOVA-2 Computer Program.

A stiffened panel extension is developed into the NOVA-2S and NOVA-2LTS computer programs which replace the NOVA-2 and NOVA-2LT programs for nuclear overpressure vulnerability and analysis of aircraft. These new versions are capable of analyzing a stiffened flat or cylindrical panel in both the elastic and inelastic response regions as well as retaining the capability of analyzing stiffeners and pure panels, individually. In the stiffened panel analysis the stiffeners are treated discretely in either or both coordinate directions and are allowed various eccentric positions relative to the single-layered, multilayered and honeycomb panel skin configurations. The stiffened panel analysis is evaluated successfully by comparing the analytical solutions with experimental results from 3 test programs that measured strains and displacement responses on stiffened panels. An evaluation of the stiffened panel analysis versus the approach of analyzing individual elements of the stiffened panel is made by comparing the two approaches on the basis of response quantities at constant range and slant ranges at constant damage level. Three stiffened panels that are very similar to those found on the B-52 aircraft were used and it was concluded that, in general, the individual element approach is not adequate and the stiffened panel analysis should be used for these types of stiffened panels.