In the Bulk Data tab, Create Design VariablesĪdd to the active list the variable you just created. Select OPTIM and its field E (Modulus) as design variable.Ĭreate fixed constraints at the base of the 2 flangesĮdit the solution. Then select the joint section collector, Edit the PSHELL2 property, and assign to it a copy of Aluminum_6061 which you rename OPTIM. Select the flange collector, and assign PSHELL1 to it. Select the general cone section collector, Edit the PSHELL1 property and select Aluminum_6061 as material. Shift-Select the 3 meshes in the sim navigator, Edit Mesh Associated Data,Īnd set the thickness source to Midsurface. Create 3 different 2D meshes and place them in the following collectors:ġ- A collector for the general cone sectionĢ- A collector for the joint section which will be optimized. Use Automatic Stitch Edge to merge the coincident edges of the flanges and the cone. Use Merge Faces to get rid of the unneeded divisions on the top of the cone Hide the original polygon geometry, keeping the newly created sheet bodies. The meshes on these faces will be assigned a material property which will be used by FE Model Update. The midsurfaced part looks like thisĬreate 4 datum planes, one on each vertical face of the 2 flangesĭivide the cone sheet body faces using the datum planes to create 4 new faces around the flange joints.
Select the solid body and click Automatically Create Face Pairs. Using the Simulation File View, navigate to the idealized part.Ĭreate an associative copy of the CAD part using WAVE linking.
#Reddit mechanical engineering calculator update#
Create a new NX Nastran FEM and SIM, and set the Solution Type to SOL 200 Model Update Go back to the part file in the modeling application.
10 modes are computed, the first being at 1318 Hz. Make the SIM the work part, select the 2 bottom faces of the flanges to define fixed constraints: Set the Solution Type to SOL 103 Real EigenvaluesĬreate a parabolic tetrahedral mesh of the part using the default size computed by Simcenter:Īs material, select Aluminum_6061 from the Simcenter materials library Starting with the CAD geometry, we first create the larger reference FEM and SIM, using NX Nastran as solver: The simplified model will provide the work solution.
In this example, we’ll take a relatively large FEM of a cone with 2 welded flanges as reference, and update a simplified, midsurfaced version of the FEM so that the modal frequencies agree well. Simcenter FE Model Correlation and FE Model Update allow you to compare the modal properties of fine and simplified FEMs, as well as to automatically update the simplified FEM to minimize the differences. Whereas plate theory can accurately predict the stiffness of each part, there can be uncertainty at the structural connections be they welded, bonded or fastened- due to the idealization of the part thickness and the creation of non-manifold joints. A common simplification technique that can be used with relatively slender parts is midsurfacing. It is often required to create lightweight, simplified versions of large FEMs in order to reduce solution time or post-processing effort. femap nx cae siemens marginofsafety mayahtt nastran The margin of safety metric is perhaps more interesting when analyzing an assembly made of different materials, each having different yield or ultimate strengths. With the different Femap contour tools, you can then plot the stress margin of safety (Figure 4) and visually identify the critical stress area of your part. The “+0.01” is to avoid division by zero for elements that may have no stress. It can be recovered using the function VEC(SetID VectorID EntityID).
#Reddit mechanical engineering calculator how to#
This post-processing Tip & Trick will show how to calculate the stress margins of safety of a structure under a static pressure load, and then how to plot the margins and locate the critical areas of the part.
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