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Session 2666

COMBINED CONTACT, BEARING AND AXIAL STRESSES LABORATORY EXPERIMENTS

Nashwan Younis Department of Engineering Indiana University-Purdue University Fort Wayne Fort Wayne, IN 46805-1499

Abstract

Stress concentrations in thin tensile plates with circular holes have been of interest to engineers for a long time. Many investigations in regard to this subject, experimental and theoretical, have taken place. This paper deals with the investigation of assembly stresses and its effects on stresses around holes. Combined contact, bearing, and axial stresses laboratory experiments were designed and constructed for the use of mechanical engineering students. Two design projects are suggested in conjunction with the proposed experiments. The goal is that these experiments is to improve the students’ comprehension in advanced mechanics of materials, experimental mechanics, or machine design courses.

Introduction

In most undergraduate Mechanical Engineering (ME) courses, the discussion of assembly stresses is relatively brief. Stress concentrations have been of interest to engineers and mathematicians for a long time. Kirsch developed the theoretical stress concentration for an infinite elastic isotropic plate containing a circular hole subjected to a tensile axial load1. This theory predicts a stress-concentration factor (SCF) of 3.0 for the hole with the maximum tensile and compressive stresses being 0 and 90 degrees from the horizontal axis of the hole, respectively. The validity of Kirsch’s solution was examined utilizing optical experimental techniques2. The solution for the circular hole in a finite-width plate under uniaxial tension was published by Howland3 in 1930. In more resent years, experimental solutions have been obtained for a wide variety of hole shapes under different loading conditions4.

The increasing industrial demand for more sophisticated structural and machine components requires a solid understanding of the concepts of stresses in members and stress concentrations around discontinuities. Students in a mechanical engineering program are introduced to the concepts of stress and strain in a solid body through the Introduction to Mechanics of Materials course. The contact stresses are then discussed in senior level courses due to the added complexity of the theoretical derivations. In the first Machine Design course, junior mechanical engineering students, learn to calculate the bolt/rivet and joint members stresses. However, in a first ME course, there is generally insufficient time to carefully consider the assumptions that are made in developing the theories and to delve into the corresponding approximate nature of the

Proceedings of the 2004 American Society for Engineering Education Annual Conference & Exposition Copyright © 2004, American Society for Engineering Education

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Younis, N. (2004, June), Combined Contact, Bearing, And Axial Stresses Laboratory Experiments Paper presented at 2004 Annual Conference, Salt Lake City, Utah. 10.18260/1-2--13690