How many Modes to Include? (Modal Truncation) - Lesson 3

In Linear Dynamics, the mode-superposition method provides a very efficient method of determining the response of a system. Since this method uses linear combination of modes for calculating the response of a structure over a range of frequencies, adequate number of modes need to be carefully extracted. This video lesson will discuss the significance of modal truncation and also discuss some guidelines and tools on how to extract enough modes. We have a short lecture followed by a workshop example to demonstrate the importance of modal truncation.

Video Highlights

01:12 - Generalized Coordinates or Modal Methods

02:05 - Extracting Optimal Number of Modes

03:22 - Guideline 1: Appropriate Frequency Range

04:10 - Guideline 2: Ratio of Effective Mass to Total Mass

05:20 - Guideline 3: Understanding Actual Modes

07:20 - Improving Accuracy with Fewer Modes

08:18 - Walkthrough Example – Clamp

Simulation Files

Download the accompanying archived project file used in the video lesson here. The student version of Ansys simulation software can be downloaded here.