Although bone fracture-fixation devices are crucial for fracture site stability, undesirable stress-shielding at locations further away from the fracture site, are problematic due to the stiffness mismatch between the bone and the fracture-fixation device. Thus, there is the need for a novel fracture-fixation plate design that provides sufficient stability at the fracture site while obviating stress-shielding away from this site. This issue can be efficiently addressed by fabricating a stiffness-graded (compositionally-graded) titanium alloy fracture-fixation plate, with low elastic modulus (or stiffness) at the ends, comparable to the bone modulus; and higher elastic modulus at the center, close to the site of the fracture. Additive manufacturing processes such as laser engineered net shaping (LENS™), a near-net shape processing technology based on direct-laser-deposition (DLD), can be used to fabricate such functionally graded alloys. This study will present the results from a novel LENS™ deposited, compositionally and functionally graded titanium alloy plate for use as a fracture-fixation device in orthopedic surgery. The gradation has been achieved between a low-modulus Ti-35Nb-10Zr (wt. %) alloy and the higher-modulus, commercially pure Ti near the center of the plate. Site-specific investigations of the microstructure, mechanical behavior, corrosion, and cyto-compatibility, along the compositional gradient will be presented.
- Understand the need for using functionally graded materials for real world applications.
- How to use the DLD-based AM systems for its full functionality in order to create compositionally graded samples for a wide range of applications.