Hydraulic Die Forming Discussion Group
Computer simulation of work hardening metal

Lee Marshall
lmarshal@bonnydoonengineering.com

I just came across this in today's San Jose Mercury News, and immediately latched upon the portion that dealt with work hardening of metals. There is a lot more, and I (being a bit peculiar about stuff like this) found it utterly fascinating.
What they have done, is to create a virtual cube of atoms and incised notches in two faces. They then applied a virtual force to see how the cube reacted to the pressure. The visuals are simply fascinating.
In one simulation, they looked at work hardening:

"In the work hardening computation, the simulated material was made to be tough, not brittle. That meant that the atoms would initially respond to stress by sliding past each other rather than simply breaking apart. The offset atoms create lines of misalignment in
the periodic structure of the material that are called dislocations. In a soft metal under stress, such dislocations simply pass through the material as deformation occurs. But in a stronger or more complex
material, various dislocations collide, which halts further atomic motion at each intersection. As deformation continues, these pinned dislocations accumulate, initially increasing the strength of the
material because it can resist a greater force. But if the stress continues, the density of pinned dislocations can become so great that the material turns brittle and breaks."

Take a look at:
www.research.ibm.com/resources/news/20020429_fracture_simulation.shtml

Enjoy

Lee

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