Modeling and constant-curvature design of a 120° spirally notched neurosurgical device using finite element method

Towards 120° spiral notch pattern, this paper proposes a finite element model to characterize the nonlinear deformation and designs an inconsistent-configuration device to achieve constant-curvature bending. Effects of the notch geometry on bending stiffness are analyzed using the model. By deriving bending stiffness equations and modeling cable friction, the non-constant curvature bending behavior of the device are characterized. A nonuniform pattern is designed to maintain a constant force-to-stiffness ratio, ensuring uniform curvature. The optimized design reduces tip displacement errors to <1.81 mm under constant-curvature assumptions. This work provides a systematic approach to modeling and optimizing notched devices for neurosurgical applications.