Design for nonsymmetrical statistical distributions

This paper presents a method for approximation of the constraint region and design centering for statistically distributed design parameters. Arbitrary uncorrelated probability density functions (p.d.f.´s) are considered, including truncated ones. The approximation problem is formulated deterministically and solved by optimization. The constraint region is approximated by a family of second-order ellipsoidal type functions. Formulation of the approximation problem takes into account statistical distributions of parameters, to be used in subsequent design centering. A special metric replaces evaluation of a multidimensional (yield) integral over the constraint region by simple integrals over fixed intervals. An additional outcome of the approximation process is location of a nominal design that increases yield