|When mating components must fit tight and prevent the use of a large radius between section changes, consider using an undercut radius to relieve the stress concentration.
The failure of a large 22" diameter shaft was the result of a stress concentration created by a 1/8" radius at a large section change. The failure is showcased in the article "Material Properties - Case Study No. 128: Mine Hoist Shaft Flange Failure at Sharp Radius Stress Concentration." All of the design details are discussed in that article. The figure to the left shows a section transition. The flange diameter in the picture was 42". The white line denotes the perimeter of the flange before the design change. The two white dots denote where material was removed for the undercut radius. The reason the 1/8" radius was used in the first place was because a drum had to fit up tightly to the flange. A large radius between the flange and the shaft would have prevented the drum from fitting snugly up against the flange. The undercut radius relieves the stress concentration caused by the large section change and allows the drum to fit up snugly with the flange along the white line.
All Pictures and Text Copyright 2002 - 2016 Contact Mr. Adler Adler Engineering LLC of Wyoming USA
|Great care has been taken in the compilation of this article. However, no warranty, expressed or implied, including without limitation, warranties of merchantability or fitness for a particular purpose, are given in connection with this article or any article archived on this website. Although this information is believed to be accurate by the author, the author cannot guarantee favorable results will be obtained from the use of this article alone. This article is intended for use by persons at their sole discretion and risk. Since the conditions of product or material use are outside of the author's control, the author assumes no liability or obligation in connection with any use of this information. The author is not liable for special, indirect or consequential damages resulting from the use of this material.
No part of this article or any article archived in this website, or any part thereof, may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, without the prior written permission of the copyright holder R. H. Adler. Nothing contained in this article or any article archived in this website shall be construed as a grant of any right of manufacture, sale, use, or reproduction, in connection with any method, process, apparatus, product, composition, or system, whether or not covered by letters of patent, copyright, or trademark, and nothing contained in this article or any article archived in this website, shall be construed as a defense against any alleged infringement of letters of patent, copyright, or trademark, or as a defense against any liability for such infringement.