You can simplify complex assemblies in several ways while seeking Simulation results if applicable. When the computational resources do not permit for simulation on the exact model, you can consider the following simplification options when working with assemblies or multi-bodies.
Keep in mind that the most accurate results are obtained by including all bodies in the assembly and using an optimal mesh size. Simplify assemblies only if you are confident that the simplification does not alter the problem you are trying to solve significantly.
• Excluding parts from simulation
Use this option when you are interested only in the results for a portion of the assembly and you can estimate the effect of the excluded bodies by applying features on the rest of the bodies.
For example, consider a case where you exert a force on the handle of a suitcase. If no other external forces are applied to the suitcase, you can model the handle alone whereas you suppress all other components or right-click a component in the Simulation Manager Tree and select 'Exclude From Analysis.'
If you are interested in the results on the suitcase body instead of the handle, you can remove the handle and apply the loads or restraints to the imprint of the handle on the suitcase body. An imprint is the common contact area that a body shares with another.
Note: In general, it is better to exclude the bodies farther away from the component you are interested in than excluding those that are nearer. It is recommended to include the bodies that are close to important bodies unless you are confident that you can apply the proper effect.
• Modeling components as remote loads/masses
You can replace the bodies that you are not interested in by treating them as remote loads/masses. The bodies will not have to be meshed, yet their mass effects will still be included. You can exclude or replace a body with its effect if the following conditions are satisfied:
1. The body itself is not of interest.
2. Its effect on the rest of the bodies can be modeled correctly.
To specify a component as a remote load, right-click on the part from the Simulation Manager Tree and choose 'Treat as Remote Mass'
• Treating components as rigid bodies
When you want to include the contact interaction between parts but save analysis time, you can treat certain components in the assembly as rigid. You can treat a body as rigid when it is much stiffer than its surrounding components or when the body is far away from the region of interest and the assembly is large. Treating components as rigid bodies leads to better approximation in the results than excluding them. The program meshes the outer boundary of a rigid body with shell elements to reduce simulation time. To treat a component as a rigid body, simply right click on a part in the Simulation Manager Tree and choose 'Make Rigid.'
• Using connectors
By using connectors for modeling springs, pins, bolts, bearings, spot welds, edge welds, links, and rigid connections, you can reduce the number of elements in the mesh and save analysis time. For example, you can model shock absorbers in automotive suspensions using spring connectors instead of modeling the actual geometry. To find the connectors, simply right click on the 'Connections' icon in the Simulation Manager Tree.
• Using surface geometries, sheet metal bodies, and structural members to model the assembly Surface geometries and sheet metal bodies mesh with shell elements and structural members mesh with one-dimensional beam elements. Using them in the assembly wherever applicable can save analysis time by reducing the degrees of freedom. For example, you can consider replacing thin solid bodies with sheet metal bodies or surface geometries.
• Simplifying Model for Meshing
You can simplify the assembly for meshing. In the Simulation study tree, right-click Mesh and select Simplify Model for Meshing. The Simplify utility determines an internal calculation of insignificant volume based on the size of the model. Supported features are listed in the task pane. You can suppress them and perform analysis on the simplified assembly.
Be careful as oversimplifying a model can produce erroneous results by altering the stress values significantly. You must not suppress features that produce high stresses in important bodies.
• Improving approximate solutions from a coarse mesh
You can initially mesh the assembly with a Coarse Mesh Density, run the study, and obtain approximate results. As the next step, you can define another Simulation study and include only those components that you are interested in. For the second step, you can find out the contact forces that develop on the outer boundaries of the smaller model from the initial study and apply them to the study defined with the finer mesh.
