Solid Works - the Solid Model

OVERVIEW

In this project, finite element analysis is used to analyze the potential failure of a machine part under certain physical conditions. For this, we use cosmos works to analyze a steel pulley which is prone to failure and verify the validity of the finite element method. As we see from figure1, a shaft is located at the middle of the mechanism and a pulley is subjected to a torque through the pulley's connecting shaft to the motor. This model is evaluated using finite element analysis. In this analysis we are going to test the design of the pulley for permanent deformation. We examine the model by using cosmos works to verify the predictions made about the consequent physical behavior of the part with appropriate boundary conditions. Finite element analysis is applied to the pulley and shaft with the applied boundary conditions. One of inner rectangular surface located inside of a hole is restrained and a 0.25 N.m torque is applied to face of the shaft. This restraint prevents rotational motion about the shaft and leads to considerable stresses at weak points. To get accurate results, various meshing methods are conducted to explore the convergence of the results. Some approaches are taken to find the best way to improve the stability of the pulley. These approaches are about the geometry of the model, boundary conditions, and material composition of the pulley.We run the analysis with different scenarios in order for us to find how exactly the design fails. To avoid failure, we redesign the part in order to improve its performance under the required conditions by using solid works and cosmos works. And also, we use a suitable factor of safety (FOS) to estimate the failure of the part.

PROCEDURE

The solid model is created by using solid works in order to run the finite element analysis in cosmos works. We define the material composition as AISI 1020 steel, cold rolled. Yield strength of this material is 350 MPA.

Now it is time to define initial settings for the pulley. The process is continued by applying a fixed restraint to inner rectangular face of one of the holes. This means that selected surface is basically immovable. Other initial setting is to apply 0.25 N.m torque to the surface of contact between the shaft and the pulley, creating a compressive force on the restrained surface. We apply with these initial boundary conditions to model the physical situation of the pulley and determine if the pulley fails or passes the failure test.

After we run the model, we expect that the maximum stress occurs at the regions where torque is applied. And also, the stresses are expected to be high on the restrained face because of compression. The displacement of the pulley to be with respect to the shaft since the pulley is powered by the rotating shaft. Large displacements are also further from the fixed position.

Now it is time to start finite element analysis with these boundary conditions. We use high mesh quality with a medium mesh density. As we know, this is second order elements