STRUCTURAL INTEGRITY OF FUSELAGE PANELS WITH MULTISITE DAMAGE

Structural integrity assessment of aging night vehicles is extremely i mportant to ensure their economic and safe operation, A two-step analy tical approach, developed to estimate the residual strength of pressur ized fuselage stiffened shell panels with multi-bay fatigue cracking i s presented in this article, Conventional finite element analysis of t he damaged multibay panel is first carried out to obtain the load flow pattern through it, The Schwartz-Neumann alternating method is then a pplied to the fuselage skin with mutiple site damage, to obtain stress es and the relevant crack tip parameters that govern the onset of frac ture. Fracture mechanics as well as net section yield criteria are use d to evaluate the static residual strength. The presence of holes with or without multisite damage ahead of a dominant crack is found to sig nificantly degrade the capacity of the fuselage shell panels to sustai n static internal pressure, An elastic-plastic alternating method is n ewly developed and applied to evaluate the residual strength of flat p anels with multiple cracks. The computational methodologies presented herein are marked improvements to the present state-of-the-art, and ar e extremely efficient, both from engineering manpower as well as compu tational costs point of view, Once verified, they can very well comple ment the experimental requirements, reducing the cost of structural in tegrity assessment programs.