What is needed to run a Finite Element Analysis?

Basic Information Needed To Run a Finite Element Analysis 

In a high level summary, the “working” steps involved in a finite element analysis may be categorized 

as:

• Modeling (pre-processing)

• Solution

• Visualization of solution results (post-processing)

Modeling / Pre-processing

CAD Data

Most commonly any FEM simulation process starts with the import of the component’s (or part’s) CAD 

geometry (e.g. CATIA, STEP, UG, IGES, SolidThinking etc.) into the pre-processor i.e. HyperMesh. 

In many cases, the imported geometry is not ready for meshing. Quite often the geometry needs to 

be cleanup first due to

• “broken” surfaces.

•  

surfaces which are not stitched together.

•  redundant (multiple) surfaces.

•  surfaces which are too small to be meshed in a reasonable way later on.

Meshing

Once the geometry is in an appropriate state, a mesh will be created to approximate the geometry.

Either a beam mesh (1-D), shell mesh (2-D) or a solid mesh (3-D) will be created. This meshing step

is crucial to the finite element analysis as the quality of the mesh directly reflects on the quality

of the results generated. At the same time the number of elements (number of nodes) affects the

computation time. That is the reason why in certain cases a 2D and 1D mesh is preferred over 3D

mesh. For example in sheet metals a 2D approximation of the structure will use much less elements

and thus reduces the CPU time (which is the time while you are desperately waiting for your results)

Material and Property Information

After meshing is completed, material (e.g. Young’s Modulus) and property information (e.g. thickness 

values) are assigned to the elements.

Loads, Constraints and Solver Information

Various loads and constraints are added to the model to represent the loading conditions the part(s) 

are subjected to. Different load cases can be defined to represent different loading conditions on

the same model. Solver information is also added to tell the solver what kind of analysis is being run, 

which results to export, etc.

To determine your relevant loads, your engineering skills are needed. Think of all kinds of load 

situations that can occur on your structure and decide whether you want to use them in your

simulation or not. To determine the load from a static or dynamic event, a Multibody Simulation 

(MBD) might be helpful.

The FEM model (consisting of nodes, elements, material properties, loads and constraints) is then 

exported from within the pre-processor HyperMesh. The exported FEM model, typically called solver 

input deck, is an ASCII file based on the specific syntax of the FEM solver chosen for the analysis (e.g. 

RADIOSS or OptiStruct).

Solution

During the solution phase of a simple linear static analysis or an eigen frequency study, there is not 

much for you to do. The default settings of the Finite Element program do handle these classes of

problems pretty well. Practice will show you that if the solution process is aborted by an “error” it 

is due to mistakes you have made during the model building phase. Just to mention a few typical 

errors:

• Element quality

• Invalid material properties

• Material property not assigned to the elements

• Insufficiently constrained model (the model shows a rigid body motion due to external 

loads)

Visualization (Post-processing)

Once the solution has ended successfully, post-processing (in HyperView for contour plots and HyperGraph for 2D/3D plots) of the simulation results is next. Stresses, strains, and deformations are plotted and examined to see how the part responded to the various loading conditions.