strain rate material modeling

[fsh1962]

I want to create stress/strain curves for Higher Strain Rates from an available stress/strain curve?
I am interested on the mathematical formulation aspect to generate a Dyna Material card.

 

[mp87]

You can't. Material behaviour is strongly influenced by strain rate and that's the reason why the tensile test is valid only within a certain range of strain rates. So you need experimental data of your material at the strain rate you're interested to. Once available, you can fit them with a suitable equation, e.g. the Johnson-Cook's one.

 

[FennLane]

There was a European Project some years ago when many of the Military Defence Establishments collaborated on a programme to plot the stress stain curves of a range of materials at very high strain rates.

The work involved testing using hydraulic machines with piston speeds of around 10 metres/second.

The effect of specimen heating on flow stresses was also evaluated by using controlled energy inputs into the test piece.

I was involved with the design of the machines used to carry out the testing programme but never gained access to the results.

It may be there is some published data by now as this work was carried out in around 1990.

 

[EdStainless]

There is publicly available data from the US military on how some material behave under crash or explosive loading.
This is a major area of ongoing research. People build machines that let them deform samples at very high rates (think higher than 10e4). Most tensile testing is done at 10e-3 to 10e-1 or so.

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P.E. Metallurgy, Plymouth Tube