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Roy Duan

How to do a material parameter validation simulation?

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Hi all,

 

As we know, we can get a stress-strain curve by doing a tensile test. But how to simulation this tensile test process to validate the parameters? In the tensile test, the loading velocity was very low (about 2mm/min), how can we simulate this in software?

 

Roy

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Hi Roy,

Please go through Example 11 - Tensile Test in the Help Menu, where material characterization is studied. 

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3 hours ago, George P Johnson said:

Hi Roy,

Please go through Example 11 - Tensile Test in the Help Menu, where material characterization is studied. 

Hi George,

Yes, the example 11 is about tensile test validation. However, in the example, the loading velocity is about 1m/s, which I think is too large. In our test, the loading velocity is about 2mm/min, and the whole tensile test process takes 10 minutes. If I use this  condition, the simulation time will be so long. How should I do this?

 

Best Wishes

Roy

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Hi Roy,

You can try the same with implicit options in RADIOSS.

There are examples on implicit cases in the Help Menu. Please go through it which shows the various cards required to activate implicit run.

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2 hours ago, George P Johnson said:

Hi Roy,

You can try the same with implicit options in RADIOSS.

There are examples on implicit cases in the Help Menu. Please go through it which shows the various cards required to activate implicit run.

Hi George,

I will try the method you mentioned.

What's the difference between implicit solver in Radioss and Optistruct solver ?   Do you have any documents about tensile test simulation by using implicit solver in Radioss?

 

Thank you 

Roy

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Hi Roy,

For static or slow dynamic computations where the duration of the study is long, many cycles are necessary to carry out the simulation implicit time-integration scheme is recommended.

OptiStruct uses Newton's method to solve the nonlinear equilibrium equation, which is an iterative method. Please go through the attached document which explains about the various solver methods available for RADIOSS implicit and its features.

Unfortunately, no documents are available on tensile test simulation in RADIOSS implicit.

Implicit.pdf

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Hi,

If you are going to be using the validated material data in RADIOSS explicit then it is important to run the validation model in RADIOSS explicit.  In explicit FEA codes, it is common to make the loading time in the simulation faster than the test to reduce the simulation time.  Then in the simulation you should check to make sure that the kinetic energy remains small relative to the total energy.  You can also use mass scaling with /DT/NODA/CST to add add mass to increase the time step of the simulation.  Or even Advanced Mass scaling /DT/AMS for an even higher time step. 

After you get a running model, you can always run it slower and without mass scaling to see if it changes the results.

Thanks,

Andy

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9 hours ago, George P Johnson said:

Hi Roy,

For static or slow dynamic computations where the duration of the study is long, many cycles are necessary to carry out the simulation implicit time-integration scheme is recommended.

OptiStruct uses Newton's method to solve the nonlinear equilibrium equation, which is an iterative method. Please go through the attached document which explains about the various solver methods available for RADIOSS implicit and its features.

Unfortunately, no documents are available on tensile test simulation in RADIOSS implicit.

Implicit.pdf

 

Hi George,

Thank you for your reply. After reading the documents, I still cannot understand the difference between implicit radioss and optistruct. I think optistruct is also an implicit solver.

 

Best Wishes

Roy

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3 hours ago, andy said:

Hi,

If you are going to be using the validated material data in RADIOSS explicit then it is important to run the validation model in RADIOSS explicit.  In explicit FEA codes, it is common to make the loading time in the simulation faster than the test to reduce the simulation time.  Then in the simulation you should check to make sure that the kinetic energy remains small relative to the total energy.  You can also use mass scaling with /DT/NODA/CST to add add mass to increase the time step of the simulation.  Or even Advanced Mass scaling /DT/AMS for an even higher time step. 

After you get a running model, you can always run it slower and without mass scaling to see if it changes the results.

Thanks,

Andy

Hi Andy,

Thank you for your advice. Maybe the explicit radioss solver cannot be used for long time during problems.

 

Roy

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