Modal Analysis & Testing Seminar

An integral part of the flight verification process for a spacecraft is achieved through validation of the finite element model of the spacecraft structure. Modal survey testing is the method used to meet this requirement. 

This course provides  an in-depth look at modal survey testing of spacecraft systems and subsystems. Emphasis is on the practical aspects of test planning, execution, data analysis  and 

post-test data processing. The techniques discussed will provide the attendee with the

necessary tools to produce a set of verified natural frequencies and mode shape vectors that represent the mass and stiffness of the spacecraft in the test configuration. 

Course Outline 

1. Introduction 

Course logistics, Overview & Outline

2. Background

Normal mode theory & description of the modal technique

3. Pre-test Analysis

Instrumentation and excitation locations, frequency range and modal density

4. Boundary Conditions

Quantifiable method to support / restrain structure

5. Instrumentation

Accelerometers, force gages as well as alternative methods

6. Facilities and Support Equipment

Mechanical and electrical requirements

7. Data Acquisition

Hardware, software, data recording, sampling and dynamic range, noise and other problems

8. Spectrum Analysis of Recorded Test Data

FFT & Frequency Response Analysis

9. Structural Excitation Techniques

Discussion of available methods of structural excitation considering nonlinearities and modal density

10. Modal Analysis of Spectral Data

Methods of turning spectra response data into modal frequencies and deformation vectors. 

11. Post Processing and Animation of Results

Making sense of modal frequencies and deformation vectors using graphical animation and correlation.

12. Verification of Modal Test Results

Gaining confidence in modal test results based on re-synthesis of spectra , Modal Assurance Criteria and graphical animation

13. Overview of Finite Element Model Correlation

Practical look at how test data is used to fine tune finite element models

14. Alternative Uses for Modal Testing

Many common (and not so common) issues that can degrade modal test data quality.

15. Avoiding Common Modal Test Problems

Response Location Problems

Test Setup Problems

Pitfalls in Data Acquisition, Processing

Practical Considerations and Tips

16. The Test Plan

17. Modal Test Demonstration

Data acquisition & processing on a test structure