AnsweredAssumed Answered

Simple Torsion Stress in Tubes

Question asked by Matthew Johnson on Oct 3, 2008
Latest reply on Oct 9, 2008 by Matthew Johnson
I'm a new user to CosmoWorks and FEA in general. I'm working on a project that involves torsion in a hollow tube. I'm making some general assumptions based off calculations for torsion in tubes as outlined in "Mechanical Engineering Design" by Shigley and Mischke. When I initially started the project, the calculations and the FEA were off by a factor. So in order to enhance my understanding of Cosmosworks, I picked two sample problems from the book. They are of torsion in a round tube and a rectangular tube. In the round tube problem, I took the properties for 1018 steel as seen in the attached pic and assumed a 3000 lbf-in input about the centerline axis. The book indicates that I should be getting 44,427 psi shear stress whereas Cosmos is showing 78,480 psi as seen in the attached pictures. In the rectangular problem, I used the material properties defined in the problem and used a 23,728 lbf-in input, from the problem, with an axis generated from the center of the rectangle. The book indicates that I should be getting 11,500 psi shear stress whereas Cosmos is showing 130,800 psi as seen in the attached pictures. Both tubes are constrained by their bottom face and have an applied torque about the top face. Is there something I'm not addressing here?

EDIT: I finally managed to work that counterintuitive attachment java app. Here are the attachmets. The problems are in the 7th edition pages 144-145. Thanks for the input.

Outcomes