BONE GRAFT - Porosity in bone graft implants.
CELLULAR TIRE - Conformal lattice as airless tire structure.
Bone tissue, like most other tissues, has the ability to regenerate when provided a space in which to grow. Bone grafting is a surgical procedure which aims to implant scaffold materials for reparative bone growth. The success of a bone graft relies on three biologic mechanisms: osteoconduction, osteoinduction and osteogenesis. Osteoconduction occurs when the graft serves as a scaffold upon which bone cells spread and form new bone. Naturally, the structural properties of this scaffold play an important role in this process. This is precisely why porosity and strength are crucial parameters in the design of bone graft implants. Through the use of lattice structures, INTRALATTICE allows us to manipulate the implant structure.
First and foremost, defining the design space required some form of medical imaging of the patient’s fracture. Based on a CT scan of the patients fractured skull, InVesalius reconstructed the set of medical images into a 3D representation. Then, by manually selecting voxels where cranial bone was missing, an implant space was defined (seen in yellow) and exported as a mesh (.stl). For the record, this process was quite tedious and a more efficient approach is needed.
Once the solid design space is defined (as a mesh, in this case), we can import it into Rhinoceros and begin the Intralattice design phase. In this particular case study, we used the UniformDS component to populate the space. Experimenting with various lattice topologies and cell sizes allows us to manipulate the porosity and strength of the implant. We're currently developing a new algorithm which emulates the trabecular structure found in bone. In that regard, we are very interested in working with specialists to fine-tune these structures.
Airless tires are of particular interest in offroad, military and extra-terrestrial vehicles. In general, the quality of such tires is largely based on resilience. However, since this property is hard to evaluate through FEA, extensive physical testing is required to validate the quality of a design. In this case study, we simply show prototypes which would be tested, the quality of these designs is unknown.
As usual, the first step was to define a design space, which in this case, was the space between the tire thread and the wheel rim. Keep in mind that for conformal lattices generated, the design space is defined by 2 of its constituent surfaces: the inner and outer surfaces.
Next, we set the various design parameters, and the lattice is generated. By changing the design parameters, we easily obtain very diverse structures.
BARE DESIGN SPACE