Chapter 16. Evaluation of the Stress State in a Buttonhead, Tensile Specimen for Ceramics
- John B. Wachtman Jr.
Published Online: 26 MAR 2008
Copyright © 1990 The American Ceramic Society, Inc.
14th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 11, Issue 9/10
How to Cite
Jenkins, M. G., Ferber, M. K. and Martin, R. L. (1990) Evaluation of the Stress State in a Buttonhead, Tensile Specimen for Ceramics, in 14th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2: Ceramic Engineering and Science Proceedings, Volume 11, Issue 9/10 (ed J. B. Wachtman), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470313053.ch16
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 1990
Print ISBN: 9780470374931
Online ISBN: 9780470313053
An analysis of the stress state in a buttonhead, tensile specimen with two types of gripping systems was conducted using finite element analysis (FEA) methods and empirical tests with strain gauges. The FEA modeling revealed stress concentrations (kt) existing at the buttonhead and at the transition from the gauge section to the shank. However, the stress field within the bulk of the gauge section is uniform and uniaxial. The buttonhead kt varied from 0.35–0.72 of the gauge section stress for tapered collet or straight collet systems, respectively. Empirical tests confirmed these results whereby the tapered collet system, compared to the straight collet system, sustained over twice the average load before failure at the buttonhead. In addition, using hydraulic couplers in the loadtrain, the percent bending at failure ranged from 0.4–4.9 (average = 2.5) and from 1.5–6.3 (average = 3.9) for the tapered and straight collet systems, respectively. A statistically based analysis was made on the effect of bending on the measurement of characteristic strengths and a practical upper limit of 5.0% bending is suggested for tensile strength tests.