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Need Help with Simulating Thermal Stresses in a Layered Plate
Posted 4 mar 2013, 14:17 GMT-5 MEMS & Nanotechnology, MEMS & Piezoelectric Devices Version 4.3a 4 Replies
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Hi Experts,
I kept running into this message:
Failed to find a solution.
System matrix is zero.
Returned solution is not converged.
I wasn't sure what exactly went wrong in my model. I'd really appreciate it if someone can help me out. I've been stuck with this same problem for a long time. Thanks a lot! I have attached my model here as well.
Below are the steps I went through... ( The idea is that I wanted to see the thermal stresses on two layers of plates as they go through temperature drop, given the values of young's modulus, poisson's ratio, thermal expansion and dimentions of the geometry, which is square in my case)
1 Go to the Model Wizard window.
2 Click the 3D button.
3 Click Next.
4 In the Add physics tree, select Structural Mechanics>Solid Mechanics (solid).
5 Click Add Selected.
6 In the Model Builder window, right-click Global Definitions and choose Parameters.
7 Go to the Settings window for Parameters.
8 Locate the Parameters section. In the Parameters table, enter the following settings:
NAME EXPRESSION DESCRIPTION
Tcontractive 100[degC] Initial temperature at stress free stage
Tpassive 20[degC] Final temperature after temperature drop
9 In the Model Builder window, right-click Model 1>Geometry 1 and choose block.
10 Go to the Settings window for block
11 Locate the Size section. In the Height edit field, type 1.
12 In the Width edit field, type 1
13 Click the Build All button.
14 In the Model Builder window, right-click Geometry 1 and choose block.
15 Go to the Settings window for Block
16 Locate the Size section. In the Width edit field, type 1.
17 In the Height edit field, type 1.
18 Locate the Position section. In the z edit field, type 1.
19 Click the Build All button.
20 In the Model Builder window, right-click Model 1>Solid Mechanics and choose Rename.
21 Go to the Rename Solid Mechanics dialog box and type Two Layers in the New name edit field.
22 Click OK.
23 Select Domains 1 and 2 only.
In the Model Builder window, expand the Model 1>Two Layers .
24 Right-click Linear Elastic Material Model 1 and choose Thermal Expansion.
25 Go to the Settings window for Thermal Expansion.
26 Locate the Thermal Expansion section. In the Tref edit field, type Tcontractive.
27 Locate the Model Inputs section. In the T edit field, type Tpassive.
In the Model Builder window, right-click Two Layers and choose Points>Fixed Constraint.
28 Select Vertex 4 only.
29 In the Model Builder window, right-click Two Layers and choose Points>Prescribed
30 Select Vertex 8 only.
31 Go to the Settings window for Prescribed Displacement.
32 Locate the Prescribed Displacement section. Select the Prescribed in y direction check box.
33 In the Model Builder window, right-click Model 1>Materials and choose Material.
34 Right-click Material 1 and choose Rename.
35 Go to the Rename Material dialog box and typePassive Layer in the New name edit field.
36 Click OK.
37 Go to the Settings window for Material.
38 Locate the Geometric Entity Selection section. From the Selection list, select Manual.
39 Click Clear Selection.
40 Select Domain 1 only.
41 Locate the Material Contents section. In the Material contents table, enter the following settings:
PROPERTY NAME VALUE
Young's modulus E 2.15e11
Poisson's ratio nu 0.3
Density rho 1000
Thermal expansion coefficient alpha 6e-6
42 In the Model Builder window, right-click Materials and choose Material.
43 Right-click Material 2 and choose Rename.
44 Go to the Rename Material dialog box and type contractive layerin the New name edit
field.
45 Click OK.
46 Select Domain 2 only.
47 Go to the Settings window for Material.
48 Locate the Material Contents section. In the Material contents table, enter the following settings:
PROPERTY NAME VALUE
Young's modulus E 1.3e11
Poisson's ratio nu 0.28
Density rho 1000
Thermal expansion coefficient alpha 3e-6
In the Model Builder window, right-click Model 1>Mesh 1 and choose Mapped.
49 In the Model Builder window, click Size.
50 Go to the Settings window for Size.
51 Locate the Element Size section. From the Predefined list, select Extra fine.
52 Click the Build All button.
53 In the Model Builder window, right-click Study 1 and choose Compute
I kept running into this message:
Failed to find a solution.
System matrix is zero.
Returned solution is not converged.
I wasn't sure what exactly went wrong in my model. I'd really appreciate it if someone can help me out. I've been stuck with this same problem for a long time. Thanks a lot! I have attached my model here as well.
Below are the steps I went through... ( The idea is that I wanted to see the thermal stresses on two layers of plates as they go through temperature drop, given the values of young's modulus, poisson's ratio, thermal expansion and dimentions of the geometry, which is square in my case)
1 Go to the Model Wizard window.
2 Click the 3D button.
3 Click Next.
4 In the Add physics tree, select Structural Mechanics>Solid Mechanics (solid).
5 Click Add Selected.
6 In the Model Builder window, right-click Global Definitions and choose Parameters.
7 Go to the Settings window for Parameters.
8 Locate the Parameters section. In the Parameters table, enter the following settings:
NAME EXPRESSION DESCRIPTION
Tcontractive 100[degC] Initial temperature at stress free stage
Tpassive 20[degC] Final temperature after temperature drop
9 In the Model Builder window, right-click Model 1>Geometry 1 and choose block.
10 Go to the Settings window for block
11 Locate the Size section. In the Height edit field, type 1.
12 In the Width edit field, type 1
13 Click the Build All button.
14 In the Model Builder window, right-click Geometry 1 and choose block.
15 Go to the Settings window for Block
16 Locate the Size section. In the Width edit field, type 1.
17 In the Height edit field, type 1.
18 Locate the Position section. In the z edit field, type 1.
19 Click the Build All button.
20 In the Model Builder window, right-click Model 1>Solid Mechanics and choose Rename.
21 Go to the Rename Solid Mechanics dialog box and type Two Layers in the New name edit field.
22 Click OK.
23 Select Domains 1 and 2 only.
In the Model Builder window, expand the Model 1>Two Layers .
24 Right-click Linear Elastic Material Model 1 and choose Thermal Expansion.
25 Go to the Settings window for Thermal Expansion.
26 Locate the Thermal Expansion section. In the Tref edit field, type Tcontractive.
27 Locate the Model Inputs section. In the T edit field, type Tpassive.
In the Model Builder window, right-click Two Layers and choose Points>Fixed Constraint.
28 Select Vertex 4 only.
29 In the Model Builder window, right-click Two Layers and choose Points>Prescribed
30 Select Vertex 8 only.
31 Go to the Settings window for Prescribed Displacement.
32 Locate the Prescribed Displacement section. Select the Prescribed in y direction check box.
33 In the Model Builder window, right-click Model 1>Materials and choose Material.
34 Right-click Material 1 and choose Rename.
35 Go to the Rename Material dialog box and typePassive Layer in the New name edit field.
36 Click OK.
37 Go to the Settings window for Material.
38 Locate the Geometric Entity Selection section. From the Selection list, select Manual.
39 Click Clear Selection.
40 Select Domain 1 only.
41 Locate the Material Contents section. In the Material contents table, enter the following settings:
PROPERTY NAME VALUE
Young's modulus E 2.15e11
Poisson's ratio nu 0.3
Density rho 1000
Thermal expansion coefficient alpha 6e-6
42 In the Model Builder window, right-click Materials and choose Material.
43 Right-click Material 2 and choose Rename.
44 Go to the Rename Material dialog box and type contractive layerin the New name edit
field.
45 Click OK.
46 Select Domain 2 only.
47 Go to the Settings window for Material.
48 Locate the Material Contents section. In the Material contents table, enter the following settings:
PROPERTY NAME VALUE
Young's modulus E 1.3e11
Poisson's ratio nu 0.28
Density rho 1000
Thermal expansion coefficient alpha 3e-6
In the Model Builder window, right-click Model 1>Mesh 1 and choose Mapped.
49 In the Model Builder window, click Size.
50 Go to the Settings window for Size.
51 Locate the Element Size section. From the Predefined list, select Extra fine.
52 Click the Build All button.
53 In the Model Builder window, right-click Study 1 and choose Compute
Attachments:
4 Replies Last Post 4 nov 2013, 17:51 GMT-5
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Posted:
1 decade ago
Arthur,
You actually don't have a 3D mesh. The mapped operation that you specified has only mapped quadrilaterals on the boundaries of your domains.
You will want to specify a Swept operation to sweep the domains with 3D elements.
Alternatively, you could also just allow the Free Tetrahedral mesher automatically mesh your domains.
Best regards,
Josh Thomas
AltaSim Technologies
You actually don't have a 3D mesh. The mapped operation that you specified has only mapped quadrilaterals on the boundaries of your domains.
You will want to specify a Swept operation to sweep the domains with 3D elements.
Alternatively, you could also just allow the Free Tetrahedral mesher automatically mesh your domains.
Best regards,
Josh Thomas
AltaSim Technologies
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Hi Josh,
Thanks a lot for the feedback. But, I was wondering if you could be more specific on the steps that I should do to sweep the domains with 3D elements?! Or, how can I just allow the free Tetrahedral mesher to automatically mesh those domains? Thanks a lot for the help!
Arthur
Thanks a lot for the feedback. But, I was wondering if you could be more specific on the steps that I should do to sweep the domains with 3D elements?! Or, how can I just allow the free Tetrahedral mesher to automatically mesh those domains? Thanks a lot for the help!
Arthur
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Posted:
1 decade ago
Or, would it be okay if you could walk me through briefly the general steps? My goal is to basically generate a thermal stress simulation on two layered plates piled on top of each other, where the bottom layer is passive and the top is active when temperature drop is applied to them.
Thank you very much for your help!
Arthur
Thank you very much for your help!
Arthur
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Posted:
1 decade ago
Arthur,
If you right-click on Mesh you can add a Swept mesh operation to the mesh sequence. The swept operation however does require manual tuning and boundary selecting most of the time (although it is getting better with later version releases). You often need to select the source and destination boundaries. You can also just add a Free Tet. operation in the same way and this operation requires less manual tuning. However, often you can get a more efficient mesh if you take the time to set up a swept mesh.
--
Best regards,
Josh Thomas
AltaSim Technologies
If you right-click on Mesh you can add a Swept mesh operation to the mesh sequence. The swept operation however does require manual tuning and boundary selecting most of the time (although it is getting better with later version releases). You often need to select the source and destination boundaries. You can also just add a Free Tet. operation in the same way and this operation requires less manual tuning. However, often you can get a more efficient mesh if you take the time to set up a swept mesh.
--
Best regards,
Josh Thomas
AltaSim Technologies