FEA (finite element analysis) is a powerful tool for design engineers that can be used to optimize the performance of a product, reduce costs, and reduce the time to market. It is used to analyze the behavior of a product under different loading and environmental conditions. With FEA, engineers can quickly evaluate the stresses, strains, deflections, and other performance parameters of a design. FEA can also be used to improve the design of existing products, by helping to identify potential weak points and areas for improvement. By using FEA, designers can quickly and accurately optimize their designs, reducing the amount of time and money spent in the design process.

What is FEA?

FEA stands for Finite Element Analysis. It is a numerical method of modeling physical phenomena, such as mechanical, thermal, and electrical systems. FEA solves problems by breaking down complex objects into smaller and simpler elements, which can be analyzed by computer. The results of FEA are used to determine the behavior of a system and the effects of various forces, such as gravity, friction, and temperature, on it.

Why use FEA

Compared to traditional hand calculation, FEA analysis offers a quick, easy, and reliable stress calculation method; it also makes engineering calculation on complex geometry possible. See below for how an FEA is conducted.

Steps of FEA analysis usually include following steps:

1. Problem Definition: The first step in the FEA process is to clearly define the problem, including the objectives, design requirements, and any applicable constraints. An accurate problem definition requires engineers’ experience and judgement. This process evolves to simplify the real world issue and apply it into a psychical model which can be used in FEA calculation.

2. Pre-Processing: Next, the model geometry, material properties, boundary conditions, and loading conditions must be defined. The model must then be divided into a finite number of elements to allow for numerical analysis, which is called meshing. Pre-Processing play an important role in FEA calculation as it directly relates to calculation accuracy and solving time.

3. Solving: Once the model is meshed, the equations of motion can be solved. This process is called solving. Solving typical is completed by computer automatically and hardware plays an important role in this process. It is common for a computer running solve a model for couple of days.

4. Post-Processing: After the equations have been solved, the results must be interpreted. This process is called post-processing. Post-processing will produce stress, strain, and displacements information. Marden software can plot these result in the 3D model and make interpretation fairly easy.

5. Validation: Finally, the results of the FEA must be verified by comparison to experimental data or another form of validation. This is the final step in the FEA process. Engineer will pick up a shape simple structure for hand calculation. By comparing hand calculation and FEA result, errors range can be determined.

Below is a simple FEA created by SolidWorks.

FEA Analysis Flow Chart
FEA Analysis Flow Chart

In above example, the analysis starts from a 3D model of a gear analysis. In the Pre-Processing we define fix positions which shown as green arrows and loading position which shown as purple arrows. After applying proper load, the model then be meshed into tetrahedron elements. By solving the FEA model, all the tetrahedron element motion has been determined. In the post-processing, the program transfers calculated results into stress pattern on the 3D model and compare to material yield strength.

As per the plot, Von Misses exceeds material yields at multi-locations which indicates the part will have permeant deformation and possible failure. Compared to hand calculation, FEA provides an easy, fast, and more thorough way to evaluate the stress condition of the part.

An accurate FEA analysis does require the user to pick up the correct load conditions and boundary conditions. Users are also required to learn basic numerical theory to build a better mechanical model.
As a approximate method, the result can only approach but never equal to the true number. A good way to reduce error is to reduce element size and check convergence, but this approach requires a large number of computer resources. Hence, the reasonable error is allowable.

Do you need FEA?

If you are a design engineer, FEA is a very handy tool. It offers an easy and convenient way to predict parts’ performance, identify potential failure points, and optimize design. ANSYS is the most common software in industry for FEA analysis, but for small engineering firm or personal design Solidworks can also provide decent FEA analysis.

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