Hi,

I think applying a velocity corresponding to a displacement will yield similar results. In fact, applying a force, displacement or velocity all will be same, if the corresponds to each other.

regards,

Anshul

Hi Anshul Faye

Thank you for your answer. In fact, one of the research I read, used the velocity option with a magnitude of 0.25 in the Z direction and eventually came up with the results of 123 kN reaction force and 3.5 mm displacement.

So, this is my point, I need to deal with the velocity option more professional so that I can come up with an accurate results.

Any suggestion that could help me please?

Regards, 

Hi,

I will try to explain you my thought in detail.

Case 1 - you apply 0.25 mm/sec velocity and run the analysis for t=14 sec, then you get a displacement of 3.5 mm and Reaction force of 123 kN at loading point.

Case 2 - you apply a displacement of 3.5 mm and run the analysis for t=14 sec, you get a velocity of 0.25 mm/sec and Reaction force should be 123 kN at the loading point.

Case 3 - you apply a force of 123 kN at loading point and run the analysis for t=14 sec, you should get a velocity of 0.25 mm/sec and displacement of 0.25mm at the loading point.

In my opinion, All 3 cases are equivalent and should give same results.

regards,

Anshul

Hi,

Ok I will try to do that. But, you mentioned t= 14 sec. Do you mean the amount of time period regarding the Step option right? Then what about the time scaling factor regarding the increment option?

Regards, 

Try running a dynamic explicit step instead of a static step and apply the velocity like a regular displacement BC.  Use the total time of the step to control how much you want your BC to displace as Anshul pointed in the example.

Hi David Restrepo

Thanks for your answer. Yes, I am using the dynamic step. But the key point is in the time scaling and mass scaling factor which I have to insert some values in order to achieve more accurate results.

My concern is how to deal with these options? On other hand, which values I have to insert to achieve an accurate results? Any suggestion?

Kind regards,

Can you give more details of your simulation? You use time and mass scaling to increase the speed of your simulation (obviously there are more considerations). Generally you don't have to input this values.. you can use the values that Abaqus uses by default. 

Hi,

Sorry for delayed response. Yes by t=14, I meant time in the step. This comes from (displacement/velocity). As David already mentioned that without time and mass scaling also you can run the dynamic analysis and there are several other considerations in using these scaling factors.

Dear Ahmed

Can't you use the Riks method instead? As you know, the Riks (AKA Arc length) method can capture any unloading, snap-back, snap-through etc. without the need to apply any specific load or displacement. You will apply a unit force and the analysis will take care of the rest.

However, if you have very high material nonlinear behavior, you may experience convergence problems.

Best,

Hi David Restrepo

1) Regarding your question about using the time scaling and mass scaling in order to increase the speed of simulation. On contrary, because those options give more analysis control and increase the time of analysis so eventually coming up with more accurate results.

2) Regarding your second part of question (Input the values). Yes, I have to input some values as some options do not come with default values as shown in the attached pictures.

Hi Anshul Faye

Thanks for your advice. However, why did you specifically suggest me to use t=14 sec? And what are the other ways to run the dynamic analysis?

Dear Sina

Riks method does not help that much to achieve an accurate results due to dealing with very complicated non-linear materials, besides I have read some papers related to my work that do not recommend to use Riks method. So the best way is employing the dynamic analysis.

Regards,

Take force applied with respect to time and go for dynamic analysis.

Dear Nitinkumar

Thanks for your answer. I assume you mean applying a magnitude of load with respect to time by using am amplitude option, right? But I do not want apply an amount of either load or displacement. I need to do the opposite procedure, and know how much load could the sample resist and how much slip could occur between the steel beam and concrete.

Regards,

Hi AHMED ALBARRAM sir

I have read your comments and others also, i also have similar doubts related to my work.Have you got some idea how to use time scaling factor and mass scaling in ABAQUS Dynamic Explicit steps???

Thnak you

Apply force with time and perform dynamic analysis.