Stiffness prediction and deformation analysis of Cobalt-Chromium lattice structures: From periodic to functionally graded structures produced by additive manufacturing

Lattice structures are candidates for innovative design of orthopedic implants and other highly functional products. In particular, functionally graded structures can be employed to achieve the required strength and stiffness for optimal stress-strain distribution. Prediction of the real behavior of these structures is essential for effective design. In the present work, stiffness prediction and deformation analysis of Cobalt-Chromium lattice structures manufactured using laser-based Powder Bed Fusion additive manufacturing were carried out. The study was developed in two steps: compressive tests and Digital Image Correlation were performed on periodic structures, with the results used to predict the stiffness of two types of functionally graded structures. The proposed method was validated experimentally, with the predicted stiffness of structures designed with the proposed elementary units within 6.1% for all tested cases. An array of stiffness data was then defined to allow free design of graded structures foreseeing specific compressive properties. The mechanical properties and deformation behavior of the structures were also investigated, with the local strain distribution mapped and compared to global deformation values.