LAW36 material curve assignment? [SOLVED]
Altair EmployeeHello,
In the RD-xxxx tutorials the stress-strain curve is assigned to fct_ID1, but I cannot find it in my Hypermesh. There is a curve assignment field under fct_ID_E, and one more field under the NFunc. If I assign it for fct_ID_E, RADIOSS gives an error that stress should decrease as plastic strain increases. If I assign to the field under NFunc, it also needs scale and EPS_DOT.
1. What are these two parameters?.
2. Eventually, where do I provide the curve?
3. Also, after creating the material, is there a way to view the true stress - strain curve just to confirm that RADIOSS interprets it correctly? I also tried the Johnson Cook material model but the results were way wrong (strain of >200% when the fail strain is 8%). So I just want to make sure the fields I am entering have correct interpretation by checking with the total stress strain curve.
Answers
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HI,
Maybe you should scroll down a lil bit when you edit the material card.
<?xml version="1.0" encoding="UTF-8"?>
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What you see is different from what I see. Anyway that is a bug.
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Hello Bongris,
So, I was using an older version of HW here. Sorry for the confusion.
Click the N_func and input 1. This will open a tab right below to refer the curve.
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Yeah that works for me! Thanks! Can you tell me what is the meaning of scale and EPS_DOT (is this strain rate for the stress-strain curve?)? The stress-strain curve is all that matters, so does RADIOSS calculate different stresses than the curve using the strain rate at that stage and then extrapolating using some theory?
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Prakash can you please tell me what is scale and EPS_DOT for the curve function?
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Hi,
This refers to the strain rate which is usually obtained form the testing data. Consider a tensile test of specimen, the rate at which it is displaced during the test is referred to as the EPS_DOT. In hypermesh, we can provide different values of the same along with the corresponding curves. Please find the attached image and for more details go the help content of MAT 36.
<?xml version="1.0" encoding="UTF-8"?>
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Thanks for your reply Gopal!
I wanted ask how RADIOSS uses the strain rate value?
For example, if the curve is with a rate 0.1 per second, how does this value get used in any way?
If the simulation has strain rate of 1 per second, will RADIOSS use a different stress-strain curve than the input?
The user guide is not at all detailed, it only gives one liner definitions.
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Can someone please answer my question?
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Can you check the law characterization document in help menu where Elasto-plastic material law characterization in RADIOSS is explained.
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