Q. Is there any guidance on how to determine the parameters for a Chaboche material model?
A. You need to start by generating cyclic test data of your material application and from the test data, determine what effects (i.e. shakedown, ratcheting) need to be modeled. From there, you can use some of the guidelines found in Chapter 5 of the Advanced Structural Nonlinear Course notes for choosing the right combination of hardening models in Chaboche to start your curve fitting. ANSYS does not currently offer tools or training expertise in the area of curve fitting for this material model.
The material model involves two physics associated with kinematic hardening and isotropic hardening. They are in turn described by two sets of parameters. A correct procedure would be to carefully set up experiments to separate the two behaviors, such that curve fitting can be performed with each one. We can't use a uniaxial tensile test to get the parameters out of it such as we do for hyperelasticity, since it is the mixed behavior from the two hardenings. Also, kinematic hardening itself has several variations, so it is hard to establish a unique experimental set up. It will depend on what the test lab can do. Hence, user needs to consult with a reputable test lab (Datapoint Labs or Axel Products).
Refer also to Mechanics of Solid Materials by Lemaitre & Chaboche, English Translation by Cambridge University Press, 1990.
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Q. Is there any guidance on how to determine the parameters for a Chaboche material model? A. You need to start by generating cyclic test data of your material application and from the test data, determine what effects (i.e. shakedown, ratcheting) need to be modeled. From there, you can use some of the guidelines found in Chapter 5 of the Advanced Structural Nonlinear Course notes for choosing the right combination of hardening models in Chaboche to start your curve fitting. ANSYS does not currently offer tools or training expertise in the area of curve fitting for this material model. The material model involves two physics associated with kinematic hardening and isotropic hardening. They are in turn described by two sets of parameters. A correct procedure would be to carefully set up experiments to separate the two behaviors, such that curve fitting can be performed with each one. We can`t use a uniaxial tensile test to get the parameters out of it such as we do for hyperelasticity, since it is the mixed behavior from the two hardenings. Also, kinematic hardening itself has several variations, so it is hard to establish a unique experimental set up. It will depend on what the test lab can do. Hence, user needs to consult with a reputable test lab (Datapoint Labs or Axel Products). Refer also to Mechanics of Solid Materials by Lemaitre & Chaboche, English Translation by Cambridge University Press, 1990. |
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