Stress analysis in solid rigid polyurethane foams due drilling processes

Abstract

In different fields of medicine there are surgical procedures that involve the drilling of bone tissue, depending on its success of the several parameters combination. The calculation and control of the involved parameters are critical to reducing the bone tissue damage. This research aims to evaluate the level of stress generated during the drilling process, using solid rigid polyurethane foams with similar mechanical properties to the human bone. During drilling of solid materials are used experimental methods, based on strain gauges and thermography, for strain analysis in the solid material and temperature calculation on the drill bit. The involved parameters in drilling are the rotational speed and the drill bit geometry always constants in different tests, with a variable feed-rate. In simultaneous, a numerical explicit dynamics model, using the finite element method, was developed through LS-DYNA program. The results allow to obtain the stress field in solid materials, function of different drilling parameters. To the same rotational speed and the drill bit geometry, the decreasing in the feed-rate, carry out the increasing in the level of stresses. Due the mechanical resistance of the rigid polyurethane
foam, for the instrumented measured zone, there is no mechanical tissue damage. The damage is caused in the hole due the perforation by the material removing.