On Approximation of Reserve Factors Dependency on Loads for Composite Stiffened Panels

We present two level approach to build accurate approximations for Reserve Factors dependency on loads for composite stiffened panels. Such dependency is continuous non-smooth function with complex form plateaux regions (i.e. regions where function has zero gradient), defined on low dimensional grids. The main problem that arises if one tries to construct global approximation in such case is the occurrence of Gibbs effect (i.e. harmonic oscillations of prediction) near the borders of plateaux that may significantly deteriorate approximation quality. Viable existing solution: approximation based on linear triangular interpolation avoids oscillations, but unlike the proposed approach it provides model that is not smooth outside plateaux regions and generally requires larger sample size to achieve same accuracy of approximation.