This article describes the workflow for performing a simple single physics static structural mechanical analysis on the Nimbix platform using COMSOL® software. COMSOL® software package offers the capabilities of performing heat transfer, electromagnetic, structural analysis, and multiphysics analysis either as stand-alone or using a high-performance cloud computing service such as the one offered by NIMBIX. The case study presented in this article will demonstrate the COMSOL® workflow on NIMBIX using COMSOL® release 5.5. The geometry used in the analysis is a CAD imported geometry, to show the process of CAD imports.
To perform the structural mechanical analysis using COMSOL® on NIMBIX cloud computing, the following steps can be followed (for detailed instructions on using COMSOL®, consult COMSOL® user manuals and tutorials):
1. Select Compute from your Nimbix account menu (the “All Apps” window will be displayed in your browser and all the NIMBIX cloud supported software will be shown). Start COMSOL® software by clicking on the COMSOL® 5.5 icon as shown below.
NOTE: If the option (for example latest COMSOL release or any other release) is not available in the first-page menu, click on “More” at the bottom of the page as shown in the image below:
2. A splash window will open. Select the COMSOL® 5.5 (or any other release you prefer) option as shown below:
NOTE: For the example that will be presented in this article (structural analysis of a bracket), COMSOL Distributed Multiphysics is selected. This will allow the user to select more nodes to decrease computation time and improve efficiency. The required NIMBIX “nodes.txt” file is automatically passed by NIMBIX to the head node so no additional input is required to distribute the job across multiple nodes.
3. The cloud set-up screen opens and here you must choose some of your settings by clicking on the Tabs on the top of the window (General, Optional, etc) one tab at a time, starting with GENERAL.
UNDER GENERAL TAB
1. Under Machine type fly-down, when clicked, you have the choice of selecting the type of machine you want to run your job on. The decision of machine type selection is based on the size and complexity of your model and cost associated with the machine type (some machines will have higher RAM, others will only run the job on single CPU, others will have better graphics and therefore higher cost, etc).
For the example presented here, we selected a 16 core Machine with 512GB RAM.
2. To decrease the computational time, select the number of cores that you believe are needed (depending on the complexity of the problem). For the example presented in this article, we will select 32 cores, which is equivalent to 2 nodes (of 16 cores each):
NOTE: The machine type you selected in the previous step, will dictate the number of cores allocated. Do not mistake the number of cores with the number of nodes (nodes represent the number of machines that you selected. In the example above, 1 node represents 16 cores, 2 nodes represent 32 cores). You can adjust the number of cores to whatever number you want, by simply typing over the default “16” next to the Cores box, the number of cores (in this case “32”) and hitting the return key to accept it.
UNDER OPTIONAL TAB
1. Assign a JOB LABEL (give a name that will help you keep track of your running jobs. For example, MyStructuralMechanics):
NOTE: Unless you have all the other information to fill in all other boxes such as “Number of processes per parameter”, etc., you can leave them blank and move on to the next Tab. These options are used to overwrite the default settings based on the selection in the “General” tab.
UNDER STORAGE TAB
1. Select vault type: Default vault is “Elastic_File”.
The “Elastic_File” vault is recommended for small to medium size jobs, such as Icepak projects, simple linear Mechanical Analysis projects, some HFSS and simple Fluent projects (not multi-phase). For any complex and computationally heavy jobs, and where partitioning the job over number of cores becomes challenging, the Performance_SSD vault is strongly recommended. The Performance_SSD vault can be found in the drop-down under “Select Vault” tab (NOTE: requires subscription and extra monthly payment to have access to Performance_SSD vault).
Before submitting your job for running, you can preview your settings under the PREVIEW SUBMISSION tab.
COMSOL STATIC STRUCTURAL MECHANICAL ANALYSIS WITH CAD IMPORT WORKFLOW
Here are the steps for setting up and solving a 3D static structural analysis with CAD imported geometry problem on NIMBIX cloud using COMSOL® 5.5 software (Model Wizard was used for setting up this problem):
1. Start by saving your model to avoid losing your work in case of a network outage (recommend saving as often as you complete important problem steps to avoid losing your work). Provide a name (try to keep it simple and if possible do not leave blank space between words) that is representative to the physics of the problem. For this example, we named the project “StaticStructMech”:
2. Under New window, click on the Model Wizard. Once it opens, select 3D.
3. Once you click on the 3D space dimension, the “Model Wizard” window will open:
4. Under Select Physics option, select Structural Mechanics to Solid Mechanics (solid):
5. Click “Add” button to add the heat transfer in solids physics to the problem.
6. Click on the “Study” button and select General Studies to Stationary option as shown below. Click the “Done” button to complete the wizard set-up.
7. At this point, we are ready to import the CAD the geometry that was created using the SolidWorks CAD design tool. In the Geometry toolbar, click Import, as shown below (be sure to select the right unit system, “mm” in this example):
NOTE: For transferring CAD files (for large assembly simulations), use FileZilla (free download from the web). Use your NIMBIX username and your API key from the web portal to access your account. If you need a refresher on FileZilla, click here.
8. Browse in the “data” folder the CAD file that you transferred using FileZilla and load it.
9. Click “Build All Objects” to accept the previous command and complete the CAD import process.
10. In the next step, we will add material from the Material Library by clicking on the Home toolbar and Materials to Add Material icon as shown below:
11. Go to the Add Materials button from the Materials toolbar and select Built-in to Aluminum 6063-T83 as shown below.
12. Click Add to Component.
13. Following the same steps as in Step 11, select Built-in to Cast iron.
14. Click Add to Component again.
15. Close Materials toolbar by clicking Add Material window.
16. Under Model Builder, click Component 1 to Materials and select Aluminum 6063-T83 (mat1) and select Domain 1, and 3 under the Selection, as shown below:
17. Similarly, under Model Builder, click Component 1, select Cast iron (mat2) and choose Domain 2 and Domain 4.
18. Assign boundary conditions (loads and constraints) by clicking on the Physics toolbar.
19. Under Physics toolbar, click Boundaries and choose Fixed Constraint (Select the relevant boundaries, for this example the fixed support is applied to the 4 screw holes), as shown below:
20. Under the Physics toolbar, click Boundaries and choose Boundary Load. Select boundary 1 as shown below:
21. Under Boundary Load to Force section, type - 5 [N/m2] under y vector. Leave all other values default.
22. The next step will be to perform the meshing of the system. Under Model Builder to Component 1 (comp1) click Mesh 1. In the Mesh settings, locate the Physics-Controlled Mesh.
23. Select Element size as Extremely fine or as needed, to get a fine enough mesh (check mesh for quality and use local mesh refinement to address any warnings or poor mesh quality that may negatively impact simulation results).
24. Click Build All, as shown below:
NOTE: Some detailed images showing all the steps above were purposely skipped to keep the case study shorter.
25. Right-click on Study 1 and choose Compute to solve your model, as shown below:
26. Monitor your CPU utilization (Click “Detailed Job Metrics” to see the utilization of your nodes during solve):
NOTE: The CPU utilization time refreshes every 30 seconds. For distributed problems, all nodes will be displayed along with CPU utilization per node.
27. Insert and review your results (select results as desired in the “Model Builder” view/tab under “Results”) as shown below:
28. Save and Exit once post-processing is completed.