Heterogeneous Object Modeling for Rapid Prototyping

A heterogeneous object is referred to a solid component consisting of two or more material primitives distributed continuously or discontinuously within an object. Modeling and manufacturing of heterogeneous object (HO) have been paid much attention recently as the advent of rapid prototyping manufacturing technology, which makes it possible to fabricate the heterogeneous object. As the continuously variation of material composition produces gradient in material properties, they are often known as functionally gradient materials (FGM), shown in Fig. 1(a). For example, a component contains two compositions, metal and heat resistance material (such as ceramic); the material distribution is illustrated in (b). From the figure we can see that metal increases its fraction gradually from one side to another (the red line), while the heat resistance material linearly reduces its fraction (the green line), which can avoid the stress concentration because of the thermal stress relaxation in transition of two materials, shown in (c). A discontinuous change in material composition generates distinct regions of material in the solid, which is usually called multi-material object (MMO) such as composite materials, as demonstrated in Fig. 2 (ZCorp (2005)). MMO has been extensively used in industry for a long time, while FGM has shown tremendous potential in many fields, such as aeronautics and astronautics, biomedical engineering, and nano-technology, etc.