DIFFERENTIATION ALGORITHMS FOR SOFT-MAGNETIC MATERIAL MODELS

Anisotropic soft materials are fully described by mapping the stored e nergy or coenergy density over the space of flux density or magnetic f ield components. This method requires accurate numerical differentiati on and reliable data. Two algorithms are described; one is fast and su itable for starting Newton iterations, the other is more costly but yi elds accurate second derivatives. Current laboratory techniques are su fficiently accurate but measurements must be spread over the coordinat e space so that numerous points lie in the multidimensional knee regio n of the material.