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Unable to plot displacement vs time graph

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Hello there,

I am using Structural Mechanics and I am able to simulate my design. I was able to get the deformation due to Internal stress and strain. I am now getting problem in plotting the graph. I am using 2D plot Group and adding Parameterized Curve 2D in Data Sets. Also, I am not able to get the correct values on x and y axis Fig.1 in attachment. Fig.2 shows the simulation of design.

I have to get time variations from 0 to 100 ms and displacement from 1.3 mm to 0 mm....

Please help....


9 Replies Last Post 17 déc. 2015, 11:30 UTC−5

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Posted: 9 years ago 15 déc. 2015, 09:00 UTC−5
Hi Swati Rastogi,

I don't understand what you want to plot? What value shall be displayed on the x-axis and what on the y-axis?

Why did you add the parameterized curve in data set? Is there a theory/formula you want to compare your results with?

Best Nicolas
Hi Swati Rastogi, I don't understand what you want to plot? What value shall be displayed on the x-axis and what on the y-axis? Why did you add the parameterized curve in data set? Is there a theory/formula you want to compare your results with? Best Nicolas

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Posted: 9 years ago 15 déc. 2015, 11:34 UTC−5
Hello Nicolas,

Thanks for the reply.

I mean to say in my query that I am unable to get the time vs displacement graph for my design. Figure 2 in previous query I showed the simulated design but I am not getting the t (ms) vs d(mm) graph.

Design is such that the microspring is to latch within 100 ms and the total distance covered is 1.3mm i.e the distance between the microspring slider and the lock. As the time increases distance to cover by microspring system will decrease. I have attached the image below, I hope it might help you in figuring what I want to say. Figure 1 shows the actual geometry. The distance between the slider and lock is around 1300um which is to be covered in 100ms.
Hello Nicolas, Thanks for the reply. I mean to say in my query that I am unable to get the time vs displacement graph for my design. Figure 2 in previous query I showed the simulated design but I am not getting the t (ms) vs d(mm) graph. Design is such that the microspring is to latch within 100 ms and the total distance covered is 1.3mm i.e the distance between the microspring slider and the lock. As the time increases distance to cover by microspring system will decrease. I have attached the image below, I hope it might help you in figuring what I want to say. Figure 1 shows the actual geometry. The distance between the slider and lock is around 1300um which is to be covered in 100ms.


Krishnaswamy Veluswamy

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Posted: 9 years ago 15 déc. 2015, 12:59 UTC−5
hi,

I would suggest you to use 1D plot group and select the line graph.
In the data set choose the solution and study for Time dependent analysis, as you had performed the solution.
Since, it is Time dependent solution, you dont need to input x-axis value as time. Its done automatically.

In the Y-axis data, choose the replacement button and select the displacement variable. and then Plot it.

Hope it works for you. All the best.
hi, I would suggest you to use 1D plot group and select the line graph. In the data set choose the solution and study for Time dependent analysis, as you had performed the solution. Since, it is Time dependent solution, you dont need to input x-axis value as time. Its done automatically. In the Y-axis data, choose the replacement button and select the displacement variable. and then Plot it. Hope it works for you. All the best.

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Posted: 9 years ago 15 déc. 2015, 14:30 UTC−5
Hi,

Thanks for the reply.

I tried to do apply the same and unfortunately I got error (Fig.3) and I am totally confused what to do. While solving problem using stationary study I am able to get simulation but not the graph while using Time dependent Study nothing is moving on now. Please help..
Hi, Thanks for the reply. I tried to do apply the same and unfortunately I got error (Fig.3) and I am totally confused what to do. While solving problem using stationary study I am able to get simulation but not the graph while using Time dependent Study nothing is moving on now. Please help..


Krishnaswamy Veluswamy

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Posted: 9 years ago 15 déc. 2015, 15:10 UTC−5
Hi,
It seems that the error had risen due to the solver settings most probably. However, I also see that the cancel button has been clicked when assembling the matrices, I have no clues why that had happened. I would suggest you to check once again the entire model BC's once more and then try to solve. If still the error still exists, please upload the model. So that everyone might help you.
Hi, It seems that the error had risen due to the solver settings most probably. However, I also see that the cancel button has been clicked when assembling the matrices, I have no clues why that had happened. I would suggest you to check once again the entire model BC's once more and then try to solve. If still the error still exists, please upload the model. So that everyone might help you.

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Posted: 9 years ago 16 déc. 2015, 00:08 UTC−5
Hi,

It is not allowing me to post the model, Size is 6.96MB and I am getting file size error. Thus, I have cleared the mesh and disabled the solution. Please help.
Hi, It is not allowing me to post the model, Size is 6.96MB and I am getting file size error. Thus, I have cleared the mesh and disabled the solution. Please help.


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Posted: 9 years ago 16 déc. 2015, 04:06 UTC−5
Dear Swati Rastogi,

Thank you for your file. It's always easier to help if you provie at least a simple model.
Concerning the file size limit, for me, it was usually sufficient to just clear the solution to reduce the file size tremendously.

Now to your problem:
1. I had no problems solving the time depent study with the settings you choosed for your model. However, I had to use very coarse mesh and large relative tolerance in order to not compute forever.

2. In order to plot the result, I used 1D Plot Group (see See image "study_and_plot.png"). You select the solution belonging to your time depent study as data set. If you have two studies (Study 1 = steady state, Study 2 = time dependent (sol2 in my case)) you may have to change the default. You can look up in the solver configuration of your study node, which solution belongs to which study. Furthermore, you have to add a graph. I used point graph, which will display only the result of one point.
Image "result_time_depent_study.png" shows the displacement over time for the point I selected. You see that I have plotted 3 curves. The total displacment is the total displacement of x,y and z but you see that the spring moves in x, y, and z. Please note, that this is just an example and you may have to adapt it to what you need to know. There might be also other, better or more appropriate methods to display what you want to show/ know.

Additionally, as far as I can see your model moves basically only in the x and y direction. You might study a 2D model, which will tremendously decrease the computation time. Moreover, you might simplify your model further. You might can remove the holes and the rodes to either side of your spring without changing the results too much. You could also simulate the simplified model first and then add further details. In this way you can get quickly results and can proove if your model works and what you can expect from your design. Then add the details for fine tuning.

Hope this helps you.

Best,
Nicolas
Dear Swati Rastogi, Thank you for your file. It's always easier to help if you provie at least a simple model. Concerning the file size limit, for me, it was usually sufficient to just clear the solution to reduce the file size tremendously. Now to your problem: 1. I had no problems solving the time depent study with the settings you choosed for your model. However, I had to use very coarse mesh and large relative tolerance in order to not compute forever. 2. In order to plot the result, I used 1D Plot Group (see See image "study_and_plot.png"). You select the solution belonging to your time depent study as data set. If you have two studies (Study 1 = steady state, Study 2 = time dependent (sol2 in my case)) you may have to change the default. You can look up in the solver configuration of your study node, which solution belongs to which study. Furthermore, you have to add a graph. I used point graph, which will display only the result of one point. Image "result_time_depent_study.png" shows the displacement over time for the point I selected. You see that I have plotted 3 curves. The total displacment is the total displacement of x,y and z but you see that the spring moves in x, y, and z. Please note, that this is just an example and you may have to adapt it to what you need to know. There might be also other, better or more appropriate methods to display what you want to show/ know. Additionally, as far as I can see your model moves basically only in the x and y direction. You might study a 2D model, which will tremendously decrease the computation time. Moreover, you might simplify your model further. You might can remove the holes and the rodes to either side of your spring without changing the results too much. You could also simulate the simplified model first and then add further details. In this way you can get quickly results and can proove if your model works and what you can expect from your design. Then add the details for fine tuning. Hope this helps you. Best, Nicolas


Gunnar Andersson COMSOL Employee

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Posted: 9 years ago 16 déc. 2015, 04:06 UTC−5
Swati, there seems to be a problem with the graphics card or driver on your computer. I suggest that you test either of the following workarounds:

- File > Preferences > Graphics and Plot Windows: Change Rendering to DirectX 9 or Software. Restart the program.

- Update the graphics drivers.
Swati, there seems to be a problem with the graphics card or driver on your computer. I suggest that you test either of the following workarounds: - File > Preferences > Graphics and Plot Windows: Change Rendering to DirectX 9 or Software. Restart the program. - Update the graphics drivers.

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Posted: 9 years ago 17 déc. 2015, 11:30 UTC−5
Hi all,

Thanks Gunnar Sir, Nicolas Sir and Krishnaswamy Sir. Your advises helped me a lot in solving my problem. I have finally got the correct simulation plot and a very good Convergence plot. My project date is 20th of this month so ultimately I have something to show in my presentation. Thanks a million.

The only problem I have now is in plotting a graph. I am able to get the axis's but not the area inside it (T vs D.png). Please help.

Hi all, Thanks Gunnar Sir, Nicolas Sir and Krishnaswamy Sir. Your advises helped me a lot in solving my problem. I have finally got the correct simulation plot and a very good Convergence plot. My project date is 20th of this month so ultimately I have something to show in my presentation. Thanks a million. The only problem I have now is in plotting a graph. I am able to get the axis's but not the area inside it (T vs D.png). Please help.

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