FEA: Are You Solving Problems or Creating Them?

Finite Element Analysis (FEA) is a powerful tool that can help engineers improve product design and avoid costly errors. However, like any complex tool, it's easy to misuse if you don't follow best practices. Engineers must have advanced training in FEA to use the method properly. Here are ten common mistakes to avoid when conducting structural analysis using FEA:

1. Failing to Define Clear Objectives

Before you start any FEA, it is essential to understand what you are trying to capture with the simulation. Do you need to know the stiffness, the peak stress, or the fatigue life? Clearly defining the objectives at the start will guide your modeling techniques and the assumptions you make throughout the process. Communicate with all stakeholders to ensure everyone understands the purpose, capabilities, and limitations of the FEA.

2. Ignoring the Physics of the Problem

FEA software can solve a variety of problems, including structural, thermal, and fluid dynamics. A strong understanding of the physics behind the phenomenon you're analyzing is crucial to ensure accurate results. You need engineering judgment and a good background in statics, dynamics, and the strength of materials.

3. Not Understanding Structural Behavior

Before modeling, you must deeply understand how the structure will behave in the real world. Don't use FEA to predict behavior; use it to validate your understanding. Your engineering knowledge should guide your model creation so you can obtain useful predictions like displacements, stresses, and strains.

4. Using the Wrong Element Type

During discretization, you must select the appropriate elements from a library that best represent the structure. Each element has specific capabilities and choosing incorrectly can lead to inaccurate simulations. Take the time to learn the various element families and choose those that are appropriate for the structural behavior, computation time, and the required accuracy.

5. Defining Unrealistic Boundary Conditions

Boundary conditions have a major impact on the accuracy of FEA results. You must have a strategy to test and validate your boundary conditions. Mistakes here can completely change the outcome of the simulation. Boundary conditions are critical to fixing displacements, applying representative loads, and simplifying parts of the model.

6. Neglecting Mesh Convergence

The accuracy of FEA is directly related to the quality and density of the mesh used to discretize components. Mesh refinement is necessary to correctly represent curved surfaces or edges, and a converged mesh produces results that do not change significantly with further mesh refinement. Always conduct a mesh convergence study to verify the accuracy of the results, particularly in regions of peak stress.

7. Misinterpreting Results During Post-Processing

Post-processing involves organizing and interpreting the vast amount of data produced by the solver. It requires following specific rules and knowing how to manage singularities. Take time to analyze and interpret results, as the quantity of data can be overwhelming.

8. Avoiding Modeling Contact

Contacts define how parts interact and are used to understand load transfer within an assembly. While contact conditions can be computationally complex, they are essential for modeling realistic behaviors. Although, in some situations, contacts can be avoided without changing the results, in other cases their use will completely change the model's response and internal load distribution. It is critical to assess whether to model contact conditions based on the specific analysis, the importance of the contacts, and your experience as an FEA analyst.

9. Choosing the Wrong Solution Type

Modern FEA software offers various solution types for different behaviors. Ensure you select the right solution by identifying whether the problem is static or dynamic, linear or non-linear, and what types of nonlinearities or contact are present. The correct selection is essential to capture the right behaviors in your simulation.

10. Not Verifying and Validating

Never assume that your FEA results are correct. You must use validation and correlation procedures when using FEA to solve problems. This includes accuracy checks, mathematical checks, and correlation with test data. When test data is unavailable, you must verify the quality of your model to ensure there are no errors.

By avoiding these common mistakes, you can greatly improve the accuracy and reliability of your FEA results. Remember that FEA is a tool to assist engineers and that your engineering judgment and understanding of the problem are crucial for a successful simulation.