Modal Tutorial 05: Experimental Modal Analysis

In the previous tutorial we saw how we could compute modal properties of a system from its mass, stiffness, and damping matrices. Unfortunately, real dynamic systems do not have mass, stiffness, and damping matrices readily available. Therefore, modes of the system must be derived experimentally, generally from the time histories of the excitation force applied to the system and the responses to that excitation measured from the system.

The sub-tutorials in this section will walk through various parts of this process to demonstrate how experimental modal analysis is performed.

Contents:

• Modal Tutorial 05 Part A: Computing Frequency Response from Time Data
  • Sinusoidal Excitation
  • Broadband Excitation
  • Computing Frequency Response Functions using SDynPy
  • Summary
  • Homework Problems
• Modal Tutorial 05 Part B: Types of Excitation for Experimental Modal Analysis
  • Requirements for the FFT
  • Considerations for Multiple-Input Excitation
  • Types of Modal Excitation
• Homework Problems
• Modal Tutorial 05 Part C: Selecting Excitation and Response Degrees of Freedom
  • Optimal Excitation Theory
  • Computing Optimal Excitation Locations
  • Optimal Response Theory
  • Computing Optimal Responses
• Modal Tutorial 05 Part D: Data Quality Checks
• Modal Tutorial 05 Part E: Fitting Modes to Data
• Modal Tutorial 05 Part F: Comparing Test and Analysis