How does Mechanical behave at strains larger than those given in the plasticity data?

I am running a static structural model with nonlinear (plastic) material data. The material data in my model is isotropic elasticity + multilinear isotropic plasticity.

I provide piece-wise points to the multilinear isotropic plasticity model, say up to a strain value of 0.50. I then apply displacement to the model until a strain in a specific location (outside surface, average over short path in region of interest) is 0.50. However, the strain in the core of the component is greater (I don't have an example to hand, but for sake of argument, say around 0.52).

I am trying to determine whether my model is still valid in this case - how does Mechanical handle the model when strain exceeds that in the plasticity model?

My thought is that strains are likely valid, since I understand the structure of the mathematical modelling to be: displacement --> strain --> stress --> force. If that is the case, the strains throughout the model area valid. The stress at the surface, where strain = 0.50, is valid. The stress at the core of the component, where strain = 0.52 (Exceeding plasticity data model) is not valid. That would be acceptable to me, as I am not interested in the stress at the core. HOWEVER, I am interested in the force reaction at my applied displacement in the model - would the validity of this be affected?

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Answers

  • Thanks, this makes sense. I am not familiar with the "tangent modulus" property, so will take a look into that. From your description though, it essentially sounds like Ansys applies a "perfectly plastic" behaviour beyond the last datapoint for the material.

  • peteroznewmanpeteroznewman Member
    edited October 5

    @langlinator Yes, perfectly plastic is the same as a zero tangent modulus.

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