New advancements in Solid Freeform Fabrication (SFF) processes promise the capability
to produce Functionally Gradient Material (FGM) parts, in which the material compositions vary
spatially. To realize this potential there is a need for CAD methods and design software to
model, design, represent and exchange material information and instructions to the
manufacturing process. However, currently available commercial CAD systems are limited to
representing and storing only geometric information, which is not adequate for material design
purposes. This work presents an extension of a theoretical approach based on Volumetric MultiTexturing (VMT) and hypertexturing schemes to make the material design process intuitive and
user controllable. Inverse distance weighted interpolation is used in conjunction with procedural
material functions to accomplish axial or linear material gradient directions from surface to
surface across a solid. This offers the capability of specifying fixed material composition values
to the faces in the solid and blending them across the interior of the solid. The extension of the
proposed approach to the modeling of discrete material domains is also discussed. These material
regions can be combined using special sets of operators depending on the form of the material
functions. Finally, a design environment has been developed, which allows users to
systematically apply material information to geometry and captures design intent.Mechanical Engineerin
