Temperature decreases instead of rising !!
Temperature decreases instead of rising !!
(OP)
Hi guy,
I would be really happy, if you could help me to solve my problem !!
Here is it:
I study residual stresses induced in orthogonal cutting.
The simulation is "dynamic-explicit-temp-disp"
The workpiece is modelled with a Johson-Cook law, conductivity, heat capacity, inelastic heat fraction etc...
And so is the tool.
The chip is built thanks to a Johnson-Cook failure criterium with element deletion.
The contacts are defined with Coulomb-friction and "heat generation"
PROBLEM: During the process, upstream of the tool's nose, the temperature of some elements decreases! But I get residual stresses under the machined surface.
If the conductivity of the material is set to a very small value (0.001 for example), there isn't any problem but no residual stresses!
It seems really that the problem comes from the conductivity...It's not a problem of units...
It makes no sense ?!?!
If the temperature decreases in some elements, where does the heat go???
Thank you for any suggestions !
I would be really happy, if you could help me to solve my problem !!
Here is it:
I study residual stresses induced in orthogonal cutting.
The simulation is "dynamic-explicit-temp-disp"
The workpiece is modelled with a Johson-Cook law, conductivity, heat capacity, inelastic heat fraction etc...
And so is the tool.
The chip is built thanks to a Johnson-Cook failure criterium with element deletion.
The contacts are defined with Coulomb-friction and "heat generation"
PROBLEM: During the process, upstream of the tool's nose, the temperature of some elements decreases! But I get residual stresses under the machined surface.
If the conductivity of the material is set to a very small value (0.001 for example), there isn't any problem but no residual stresses!
It seems really that the problem comes from the conductivity...It's not a problem of units...
It makes no sense ?!?!
If the temperature decreases in some elements, where does the heat go???
Thank you for any suggestions !





RE: Temperature decreases instead of rising !!
I think you may check the energy dissipated from the contact, as an output variable. You can check first of all if there is really an energy dissapation during the process.
RE: Temperature decreases instead of rising !!
In other words, you should try eliminating one of your heat sources to see if that helps you isolate the problem.
The reason that the elements are getting colder is probably because one area is drawing heat away from them erroneously in order to maintain energy balance. By reducing the conductivity, you are reducing the ability of the bad zone to pull heat away from those far away elements... But you still have a bug; the low conductivity is just masking it.
RE: Temperature decreases instead of rising !!
I already tried to turn alternatively off the heat generation and the inelastic heat fraction but it doesn't change anything to my problem.
And I still have the problem.
Any other suggestion?
RE: Temperature decreases instead of rising !!
RE: Temperature decreases instead of rising !!
But there is the problem without too.
RE: Temperature decreases instead of rising !!
For you:
Absolute Zero = 0 K
Stefan Boltzmann = 5.67 × 10–8 kg s^-3 K^-4
From Abaqus manual:
*Physical Constants
ABSOLUTE ZERO
Set this parameter equal to the absolute zero on the temperature scale chosen. For example, if the analysis uses temperature in degrees Celsius, set ABSOLUTE ZERO=–273.15.
STEFAN BOLTZMANN
Set this parameter equal to the Stefan Boltzmann constant. For example, STEFAN BOLTZMANN=5.669 × 10–8 Joule per sec m2 Kelvin4 in SI units.
RE: Temperature decreases instead of rising !!
Really thank you for your help Vumat721.
RE: Temperature decreases instead of rising !!
Here are some files which could help you to understand better the problem:
1: The temperature in an element on the surface of the machined surface: http://f
2: The domain in which the temperature decrease (in dak-blue): http://f
Other suggestion ?
RE: Temperature decreases instead of rising !!