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Problems with MAT9ORT

I'm having some problems using MAT9ORT. I'm analyzing a 3D printed prosthesis, but when I use MAT9ORT the resulting displacement is huge, but when I use MAT1 as an approximation (the values in the three directions are not so different) just to compare, the displacement it is ok. The MAT9ORT are giving me a displacement 100 times bigger. Can someone help me with it? Does anyone have an idea what is causing this? like a wrong deffinition on the parameters of the material for example. Thanks a lot.

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Adriano_Koga

Can you provide more details on what properties are you using?

Are you setting the material direction correctly?

Nayara Lacerda

Can you provide more details on what properties are you using?

Are you setting the material direction correctly?

Hello, Adriano. Thank you for answering. I am using the E, G and Poisson properties. I think I am using the material direction correctly. And, even if it was incorrect, the results should not be not so different because the properties are close in the three directions, what (in my opinion) does not justify getting a hundred times larger displacement just by changing the material law.

Adriano_Koga

Hello, Adriano. Thank you for answering. I am using the E, G and Poisson properties. I think I am using the material direction correctly. And, even if it was incorrect, the results should not be not so different because the properties are close in the three directions, what (in my opinion) does not justify getting a hundred times larger displacement just by changing the material law.

Hi Nayara,

MAT9ORT is actually very senstitive to the input values, even poisson and Gij values.

Even some small differences might lead to numerical instabilities in the model.

There are some stability checks for this kind of material, that you can see in the MAT9ORT documentation in OptiStruct help.

Hope this helps you somehow.

Adriano