GENERATIVE DESIGN OF COMPOSITE WEARABLE DEVICES

Design of lightweight (weight-minimized) composite structures that can meet stiffness, strength, and manufacturing constraints is challenging and time-consuming. Numerous constraints from wearable medical devices such as orthotics and exoskeletons, have geometric constraints from the user's anatomy determining their fit, comfort, and safety during wear. This paper presents a generative design methodology to create composite wearables customized to the user's anatomy. Design automation begins with a 3D scan of the relevant anatomy as input and produces 3D printable composite structure components. Through constrained optimization, the design process is accelerated by establishing the structural geometry, reinforcement fiber insertion paths, and manufacturing process plans. The methodology is illustrated on a patient-customized active ankle orthosis design. The geometric constraints are derived from a lower limb scan, and a patient-customized contact surface was generated and the fit is evaluated based on curvature and smoothness metrics. The surface is thickened to create a 3D structure, and the fiber reinforcement paths are determined based on the strength, stiffness, and limitations of additive manufacturing machinery. Considerations from the composite Process-Structure-Property-Performance (PSPP) relationships allow the considerations void and defect introduction by the 3D printing process. The insertion of generative design, automation, and optimization techniques reduced the scan to a real part cycle from several days to about 18 hours. The paper presents treadmill walk testing results from 15 healthy subjects.