Modal analysis in Creo

While there are several analogous ways to test for modal analysis, we use the analytical approach using Finite Element Analysis. This utilizes numerical methods to simulate and analyze the dynamic behavior of structures. It involves creating a finite element model of the structure and solving equations of motion.
To learn more, reference this support article.

Modal analysis in the context of Finite Element Analysis (FEA) is a numerical method used to study the dynamic behavior of structures. FEA is a computational technique that divides a complex structure into smaller, simpler elements, allowing engineers to analyze and simulate its behavior under various conditions. Modal analysis, specifically in FEA theory, focuses on extracting the natural frequencies, mode shapes, and damping ratios of a structure.

Here's an overview of modal analysis in FEA theory:

• Finite Element Model (FEM):
  • A structure is discretized into finite elements, which are interconnected at nodes
  • Material properties, geometry, and boundary conditions are defined for each element
• Equation of Motion:
  • The dynamic behavior of the structure is described by the equations of motion, which are typically second-order ordinary differential equations (ODEs).
• Eigenvalue Problem:
  • Modal analysis transforms the ODEs into an eigenvalue problem, where the natural frequencies (eigenvalues) and mode shapes (eigenvectors) are the solutions.
  • The eigenvalues represent the frequencies at which the structure tends to vibrate, and the eigenvectors represent the corresponding mode shapes.
• Solving the Eigenvalue Problem:
  • Numerical methods, such as the Lanczos or QR algorithm, are used to solve the eigenvalue problem and obtain the natural frequencies and mode shapes.
• Post-Processing:
  • Once the eigenvalues and eigenvectors are obtained, engineers analyze the results to understand the structure's dynamic behavior.
  • Natural frequencies indicate the rates at which the structure vibrates under free conditions.
  • Mode shapes show the spatial distribution of vibrations associated with each natural frequency.
• Damping Ratio:
  • Damping ratios can also be determined to quantify the amount of energy dissipated during vibration.
• Modal Superposition:
  • Modal superposition is a technique used to represent the dynamic response of the structure as a combination of modal contributions.
  • This approach simplifies the analysis of complex dynamic loading conditions.

Modal and buckling analysis are crucial in structural engineering to assess the dynamic and stability aspects of a design. Modal analysis helps determine the natural frequency modes of vibration, essential for understanding a structure's response to dynamic forces. It automatically handles rigid modes, providing insights into unconstrained vibrations. On the other hand, buckling analysis is vital for assessing structural stability, identifying critical loads, and solving unstable snap-through problems. By determining buckling loads, engineers can ensure designs withstand compressive forces without catastrophic failures. Together, modal and buckling analysis contribute to optimizing structures, preventing resonances, and ensuring stability under various loading conditions.

Designed uniquely for the engineer, PTC’s simulation software has the familiar Creo user interface, engineering terminology, and seamless integration with CAD and CAE data. You have at your fingertips a complete structural, thermal, and vibration analysis solution, with a comprehensive set of finite elements analysis (FEA) capabilities.

When you want real-time feedback as you design, choose Creo Simulation Live powered by Ansys. Just define a few simple conditions and the software does the rest, presenting results in real time as you edit or create features. That’s not just convenience and speed, that’s design guidance as a normal part of your workflow.

When you want a comprehensive analysis of your model while you design, choose Creo Ansys Simulation (CAS) or Creo Ansys Simulation Advanced (CASA). While both are built for design refinement and validation, CASA has the added benefit of supporting use cases like non-linear contact and non-linear materials. CASA also allows you to run combined structural and thermal studies.