Finite-element modeling of a bevel-tipped needle interacting with gel

Deviation of a needle from its intended path can be minimized by using a robotic device to steer the needle towards its target. Such a device requires information about the interactions between the needle and soft tissue, and this information can be obtained using finite element (FE) analysis. In this study, we present an FE analysis that integrates the Johnson–Cook damage model for a linear elastic material with an element deletion-based method. The FE analysis is used to model a bevel-tipped needle interacting with gel. The constants for the damage model are obtained using a compression test. We compare simulation results with experimental data that include tip–gel interaction forces and torques, and three-dimensional (3D) in situ images of the gel rupture obtained using a laser scanning confocal microscope. We quantitatively show that the percentage errors between simulation and experimental results for force along the insertion axis and torque about the bevel edge are 3% and 5%, respectively. Furthermore, it is also shown qualitatively that tip compression is observed at the same locations in both experimental and simulation results. This study demonstrates the potential of using an FE analysis with a damage model and an element deletion-based method to accurately simulate 3D gel rupture, and tip–gel interaction forces and torques.