PRINTING THESIS PROJECT BY MIHAI DRAGOS POTRA
SELECTIVE MATERIAL DEPOSITION Bone is a unique natural material that can solve many structural problems generated by the mechanical stresses and applied loads on it. The solution lies in the selective material deposition approach, the ability to configure one or more materials into a structural geometry that will give to the bone element its characteristic strength while keeping a minimum ration of material/volume. This will allow the bone to perform in a most efficient way under heavy loads or stresses while keeping its body as light as possible. The bone material distribution acts as a FGM (functionally graded materials)in which each “layer� has its own function. The outer layer, periosteum, is uniform and continuous and allows for the cartilages of the muscles to bound on it. It follows then the compact bone, that is the main body of the bone, that evolves towards the central axis of the bone to a spongious structure also called the cancellous bone. This layer has the role to distribute the stresses from one side of the compact bone to the other while keeping the minimum material. It will reinforce or weaken by reconfiguration/alteration of its pattern or assimilation/loss of material mass. Besides the material location distribution the bone has to ability to entangle different materials with different proprieties into one mass for a better performance. The solution consist of a matrix of collagen fibers, a protein which is strong in tension (collagen is the main component of skin and tendons) that creates a matrix which is then filled in with calcium salts, which are strong in compression, analogous to concrete.
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