What is Finite Element Analysis?

  • 7th March 2019
  • Romilly Close
  • Reading time: about 4 minutes

Want more detail? Read the next article in our FEA Explainer series, How to create a great model.

When bringing a new design to production, engineers must prove that it can withstand the expected (and unplanned) loads throughout its lifetime. In the past, prototypes or test specimens were created and physically tested to prove the concept. This kind of design development is very expensive, and usually not feasible for experimental or safety-critical designs. Increasingly engineers are relying on Finite Element Analysis (FEA) to influence design choices.

FEA is a computer-based numerical-analysis technique which involves breaking down large, complex structures (‘models’) into a mesh of discrete elements. The elements are connected to each other, at points called ‘nodes’, creating a continuous surface. The model is ascribed some material properties; it is restrained (to allow the forces to act in a physically realistic manner); a loading scenario is applied; and the FEA software generates sets of equations according to the shape of the elements and material properties. The equations are then solved to produce a visual representation of the results. FEA models can be used for almost any combination of loading types, including point forces, moments, pressures, and thermal loads. Models can be constructed for linear or nonlinear, static or dynamic loading, as well as scenarios such as impacts, fluid flow, buckling, heat transfer, and natural frequency analysis.

In this way, many iterations of the simulated load cases can be carried out quickly, reducing the reliance on actual tests and prototyping – thereby improving confidence and saving resources before committing to producing a physical object.

Generally, FEA is split into three steps: creating a model during pre-processing, solving that model, and then analysing the results during post-processing.

Using FEA modelling it is possible to model anything from flexural test specimens to entire aircraft.

Strengths of Finite Element Analysis

  • FEA modelling is incredibly versatile software and can be used to model almost any real-world scenario.
  • It can be used to create fast iterations of designs without the cost of producing, testing, and then discarding real parts.
  • The results can provide reassurance that a structure can withstand the imposed forces over its service life.
  • The model can optimise the structure by showing areas that need localised reinforcement or different materials, saving the manufacturer time and materials costs.
  • Used carefully, FEA is a powerful tool in the modern engineer’s arsenal.

Weaknesses of Finite Element Analysis

  • FEA involves complicated (and usually expensive) software.
  • Models can have ‘artefacts’ or incorrect results caused by using inappropriate element types.
  • It is too easy to get inaccurate or even useless results due to incorrect modelling.
  • Complicated models or solution methods can take hours (or even days) to solve.
  • Deciding on a load case to apply to a model can be difficult or even impossible, especially as real loading scenarios are rarely straightforward.
  • Composite materials are very difficult to model accurately, resulting in non-optimised structures that can’t be shown to compete with metal.

View the next in our series of FEA Explainers, How to create a great model.

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About the author

Romilly Close

Romilly is a development engineer at Coventive Composites

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