Designing Graded Structure with Custom-Fit

Custom-Fit is an industry led project funded by the EU under Sixth Framework Prog ramme, with the aim of creating a fully integrated system for the design, production and supply of individualise products using Rapid Manufacturing technologies. One of the objectives of Custom-Fit is to manufacture products with graded materials in a single manufacturing process. To facilitate this, it has developed a new design philosophy and verification of product designs with graded structures.

Commercial computer aided design (CAD) systems in general are used for designing the geometry of an object and are not capable of describing the material composition of the object. The project has gathered experts from around Europe to develop three design systems for representing products with graded structure. TNO from Netherlands, Fraunhofer-IFAM from Germany and Materialise from Belgium are three of the partners in the Custom-Fit project. Each of them has defined a method for describing the structural design of a product based on different philosophy. The three software are InnerSpace by TNO, Multi Phase Topology Optimisation from IFAM and a FEA representation method by Materialise. These software offer the ability to define the proportion and distribution of materials within an object.

Lieve Boeykens from Materialise, who is leading the software development in the project, said that these software are very unique. She says, “These are very strong product, they maybe lighter in terms of data size but they are able to define the graded structure and deposit the material properly. It is not just our partners in the project who will benefit from these developments; eventually other market players will be able to use the same software, too. ”

Each of the three software has different strength and is suitable for the modeling of different product.

· InnerSpace, by TNO, enables a designer to define material property distributions and also the distribution profile. The software uses the STL file as the source file and the STL model defines the outer boundary of the object. It can define the material distribution for a whole object or just part of the object at any location. The data files from InnerSpace is very small and thus easy to transfer.

· Multi Phase Topology Optimisation (MPTO), by IFAM, is a numerical simulation technique based on finite element method. It is able to determine the optimum distribution of two or more different materials in components under thermal and mechanical loads. It finds an optimal spatial distribution of several different materials in order to achieve highest stiffness.

· Materialise also uses the FEA method to define a geometric model that consists of a large number of small scale volumetric elements. Each element can carry as many properties as the designer wants to define. It also enables the designer to define the material deposition within the object.

The field of graded material design is an emerging market and there are many new opportunities. Custom-Fit is using the software for the design of a range of products, including implants, prosthesis, helmet and seats. The availability of software for designing graded structure opens up the possibility of designing products with better mechanical structure. The next step would be to be able to manufacture such products. The project is now working on interfacing these software to additive manufacturing machines and thus realising the printing of products with graded structure.