Instability in Tensile Deformation

The exercise shows a 8" long tensile test specimen. The material obeys the flow stress = s = Ken behavior. Both engineering stress-engineering strain and true stress-true strain curves are shown.

The questions are:

  1. At what value of engineering strain does necking start?
  2. What is the value of true strain at the onset of necking?
  3. Is the strain at the onset of necking related to the strength coefficient K?
  4. Is the strain at the onset of necking related to the strain hardening exponent n?
The start of necking is easier to see on the engineering stress-engineering strain curve.
Click "Reset" to initialize.
After setting values for K and n, clicking "Start/Stop" will begin simulation of material deformation.
Both engineering stress-engineering strain and true stress-true strain curves are displayed.
The process can be stopped and restarted with "Start/Stop" button.

If you see this message rather than an animation, your browser is not Java enabled - the rest of the exercises will not run either.


Procedures for answering the questions posed and a quantitative model of the onset of nonuniform deformation in tension are HERE

© 2001 by Barney E. Klamecki. All rights reserved