Features in Layered Manufacturing of Heterogeneous Objects

The usage of features in computer aided design and manufacturing has increased significantly over the last decade. By and large, all such features are geometric (form features). In this paper, we shall discuss the need to go beyond current geometric features and consider material -composition, and gradation -within the object. This need has been brought about by layered manufacturing technologies which build up parts, layer by layer, under computer control. While industrial use of this new technology has been for making prototypes, functional metallic parts can/are being made by layered manufacturing. Furthermore, a variety of materials can be deposited to create multi-material and functionally graded components. We consider features in this new domain (of layered manufacturing) and identify research topics and present an overview of our current focus on "material features" in the context of heterogeneous solid models. 1.0 Introduction Layered manufacturing(LM) refers to the host of manufacturing technologies that deposit material, layer by layer, under computer control. It is also referred to as solid freeform fabrication (SFF) and in industry as rapid prototyping. Layered manufacturing methods can be used to make functional parts which have good surface quality and good material property. One distinguishing characteristic of LM is that it is capable of depositing multiple materials in a layer as welLas varying the material composition. Harnessing this characteristic is the focus of our research. In this paper, we consider heterogeneous objects i.e., objects made of different constituent materials and having continuously varying material composition and/or microstructure (See Fig. 1). The state-of-the-art design and analysis research indicatesthatheterogeneous objects naturally arise in the context of thermal expansion coefficients, mechanical strength, creep,. thermal and electrical conductivity, etc. Applications ofheterogeneous objects include automotive engineering, aerospace, and biomaterials, etc.