Abstract
Making a diameter of needle small is effective for reducing the pain of patients. However, thinning a needle leads to easy buckling in the puncturing process, because the aspect ratio of needle becomes high. We propose the method for avoiding buckling of thin needle by setting a guide around it. This guide can limit the lateral displacement of needle, making the stress lower than material fracture stress. Using FEM software (COMSOL Multiphysics) the displacement and stress of needle after buckling was simulated. This simulation took into account large deformation and contact model. The simulation results show that 1) the deformation of needle is stopped after contact, 2) the initial gap between guide and needle is smaller, the stress is lower, and 3) the maximum stress can be set lower than material fracture stress.
