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plasticity

Pioneer
Pioneer
I am trying to do temperature dependant plasticity using 601(Advance non linear statics) solver but when i applying temperature dependant stress strain value(plastic hardning data) in stress strain related properties (mat 1) and non linearity as a plastic i got following error Some of the tangential modulii calculated from the stress-strain data for material "Waspaloy_1" do not fall within the acceptable range for isotropic hardening in NX NASTRAN. but i read in siemens help file their they mention as ''In NX Nastran, only linear and nonlinear elastic materials can be temperature dependent. Elastic-plastic and hyperelastic materials can’t be temperature dependent''. Please suggest me how can proceed further.Thank you
1 REPLY

Re: plasticity

Siemens Phenom Siemens Phenom
Siemens Phenom

In the NX Nastran Quick Reference Guide, Remark 1 for MATS1 states:

 

Thermo-elastic analysis with temperature-dependent material properties is available for isotropic linear and nonlinear elastic materials (TYPE = “NLELAST”) and anisotropic linear elastic materials. Four options for the constitutive relation exist. These options are listed in Table 15-3 along with the required bulk entries.

 However, this remark does not apply to SOL 601. There are a special section of remarks for SOL 601 & 701. In this section, Remarks 5, 10 and 11 are applicable to your issue:

 

5. TID can reference a TABLEST entry for TYPE = “PLASTIC” but not for TYPE = “NLELAST”.

10. If the slope of the line joining the origin and second point in TABLES1 (for TYPE = “PLASTIC” and a given TID) is not equal to the value of E in MAT1 entry, the strain value at the second point will be adjusted accordingly.

11. If TYPE = “PLASTIC”, all tangent modulii ETi must satisfy the following:
  ◦HR = 1: ETi < E

    ETi can be negative when HR=1. Caution: Under certain modeling
    and loading conditions, a negative ETi may prevent a solution
    from converging and cause a failure.

  ◦HR = 2: 0.0001 * E < ETi < E

  ◦HR = 3: 0.0001 * E < ETi < E

 

You can specify temperature dependent plasticity for SOL 601. Your issue is probably related to the bounds on Et noted in Remark 11.