Cutting Force of Hollow Needle Insertion in Soft Tissue

This paper presents a 3-D finite element model (FEM) using cohesive zone (CZ) concept to simulate the hollow needle insertion and identify the change in cutting force. CZ is a FEM technique that integrates the fracture mechanics based on surface energy and has often used in analysis of crack propagation. Experiments of needle insertion into the soft polyvinyl chloride (PVC) phantom tissue were conducted using two types of needle (bias bevel and lancet) under a constant speed to identify friction and cutting forces. Using the CZ concept, a thin layer of FEM is built to observe the tissue flow and cutting force along the needle cutting edge during insertion. Both experimental observation and modeling results show higher cutting force for the lancet tip due to smaller rake angle along the cutting edge. This FEM approach has demonstrated the potential as being an analysis tool for hollow needle insertion.