We’ll use a “Frequency analysis” sample to kick off our first case.
Frequency analysis in Finite Element Analysis (FEA) is a method to determine a structure’s natural frequencies and their corresponding mode shapes, which represent how it will vibrate at those frequencies. This is crucial for understanding and predicting a system’s behavior under dynamic loads, identifying potential problems like resonance, and optimizing the design to avoid failure or excessive vibration. The analysis works by using the model’s stiffness and mass properties to calculate these inherent vibration characteristics.
How it works #
- Modal analysis: This is the most common type of frequency analysis and is used to calculate the natural frequencies and corresponding mode shapes of a structure under no external load.
- Inputs: The analysis requires the material properties (like stiffness and density) and the model’s geometry and boundary conditions to be defined.
- Outputs: The result is a set of frequencies (eigenvalues) and the associated shapes of deformation (eigenmodes or mode shapes) at those frequencies.
- Frequency response analysis: A specialized type of transient analysis that calculates the steady-state response of a structure to a sinusoidal load at specific frequencies.
Why it’s used #
- Avoiding resonance: By comparing the natural frequencies to the frequencies of the loads the structure will experience, engineers can ensure they are not close to each other. Resonance occurs when the forcing frequency matches a natural frequency, leading to large, potentially destructive vibrations.
- Design optimization: Frequency analysis helps in the design phase to identify potential issues early, allowing for changes to be made to the geometry or material before prototyping, which saves time and cost.
- Dynamic load assessment: The results, particularly the natural frequencies, can be used as input for other analyses, such as seismic or wind load assessments, to understand how a structure will behave under extreme conditions.
- Predicting system behavior: It provides valuable insights into the fundamental dynamic characteristics of a system, helping to optimize its performance and reliability.