Presentation given to the Solid Freeform Fabrication Conference, Austin, TX 8/2006
Cellular solids studies the mechanical effects of the material arrangement of architectures for the goal of designing materials which are lightweight and possess high structural integrity. These architectures present themselves frequently in structural members in nature (bone, plant stalks, and porous rock) and are now used frequently in design (tissue engineering scaffolds, mechanical design). Until now however, physical studies of these architectures have been completed using molding techniques (for 2D) and random models (for 3D). Rapid prototyping (RP) provides high repeatability during replication which decreases error in studied samples and can serve to reduce the number of conflicting variables which confound the development of structural relationships. In this study we designed and characterized four geometric solids from the Platonic and Archimedean set of polyhedra, the simplest architectures that exist in nature which exhibit symmetry and order. Multiple models of these polyhedra were generated using computer aided design at similar topologies but with varying volume fractions. Employing finite element analysis we analyzed the structures with simulated uni-axial linear compressive tests. We then built actual models of the architectures using solid laser sintering (SLS) with a Sinterstation 2500Plus. The architectures were printed at porosities of 80% and 90% by volume with a bounding box of 2cm x 2cm x 2cm. After printing of the models, they were scanned with micro-computed tomography (µCT) as a validation of the use of SLS for fabrication of computer modeled architectures. Finally, the architectures were compressed to fracture using an MTS, validating the modeling component of the design and providing information which will allow for the determination of relationships which govern the material arrangement and resulting mechanical properties. These results of this study are useful in the development of models which directly relate complex architecture to mechanical properties; these models can be used to develop any architecture based on given input parameters such as porosity, surface area, connectivity and fracture pattern.