Patran-Nastran: User fatal message 25004 "POISSONS RATIO OF MAT1 ID 2 IS LESS THAN ZERO OR GREATER THAN 0.5"

[luca.vicari1996]

Hello everyone. I’m an aerospace engineering student. For the thesis work, I am performing a nonlinear implicit analysis (SOL 400) and I have a problem. In particular I am realizing a hertzian contact between a steel cylindrical indenter and a plate with the following equivalent mechanical properties: E=1.3086e+09 Pa and Poisson ratio =-0.5166.
I realized the contact conditions and set up the analysis. The analysis setting can confirm that it is correct because previously set up the same analysis but with the plate made of aluminum , Nastran did not give problems.
If I assign to the plate a material (isotropic) with the mechanical characteristics described above, Nastran in f.06 reports that " USER FATAL MESSAGE 25004 (TA1M)- POISSONS RATIO OF MAT1 ID 2 IS LESS THAN ZERO OR GREATER THAN 0.5".
I cannot understand how to solve this problem, since my aim is to analyze how a plate with a negative Poisson ratio behaves.
if anyone can help me I would be very pleased.

[John_Holtz · Accepted solution]

Hi @luca.vicari1996 . Welcome to the Autodesk Nastran forum.

Are you using Nastran from MSC? (MSC is the company that produces Patran. The error message is not from Autodesk Nastran.) You should contact the company that produces the solver (probably MSC but perhaps another vendor) and ask them if there is a method of analyzing a material with a negative Poisson's ratio.

As indicated by the message, a MAT1 material model (isotropic material) cannot be used.

John