  This paper proposes a novel density-based method for structural design
considering restrictions of multi-axis machining processes. A new mathematical
formulation based on Heaviside function is presented to transform the design
field into a geometry which can be manufactured by multi-axis machining
process. The formulation is developed for 5-axis machining, which can be also
applied to 2.5D milling restriction. The filter techniques are incorporated to
effectively control the minimum size of void region. The proposed method is
demonstrated by solving the compliance minimization problem for different
machinable freeform designs. Several two and three-dimensional numerical
examples are presented and discussed in detail.
