Table of Contents

## What is mass participation in modal analysis?

Effective mass factors – the effective mass factors associated with each mode represents the amount of system mass participating in that mode in a given excitation direction. Therefore, a mode with a large effective mass will be a significant contributor to the system’s response in the given excitation direction.

## What is effective mass in vibration?

The effective mass offers a physical interpretation of a physical system with multiple modes of vibration being excited dynamically from a base, similar to testing that occurs for many systems. The concept was proposed in the early 70’s by Bamford[1] with others.

## What is modal mass participation ratio?

Context 1. mass participation ratio specifies the percentage of how much the structural mass of the model is participating for a given direction and mode. Table 2 shows the natural frequency for particular mode as well as the mass participation ratio in every direction.

## What is effective mass in modal analysis?

The effective modal mass provides a method for judging the “significance” of a vibration mode. Modes with relatively high effective masses can be readily excited by base excitation. Perhaps the number should be enough so that the total effective modal mass of the model is at least 90% of the actual mass.

## What does modal analysis tell you?

Modal analysis helps to determine the vibration characteristics (natural frequencies and mode shapes) of a mechanical structure or component, showing the movement of different parts of the structure under dynamic loading conditions, such as those due to the lateral force generated by the electrostatic actuators.

## What does modal mass mean?

MODAL MASS MATRIX When the mass matrix is post-multiplied by the mode shape matrix and pre-multiplied by its transpose, the result is a diagonal matrix, shown in equation (4). This is a definition of modal mass.

## What is the purpose of a modal analysis?

## How is the effective modal mass used in vibration?

By Tom Irvine Email: [email protected] June 23, 2009 Introduction The effective modal mass provides a method for judging the “significance” of a vibration mode. Modes with relatively high effective masses can be readily excited by base excitation. On the other hand, modes with low effective masses cannot be readily excited in this manner.

## Which is the effective modal participation factor for Mode I?

The modal participation factor for mode i is (26) The modal participation vector is thus (27) The coefficient vector and the modal participation vector are identical in this example because the generalized mass matrix is the identity matrix. The effective modal mass for mode i is (28)

## Why is mass participation important in modal analysis?

As you can see this ratio is in direct comparison with total mass, which gives a better clarity on how much of the total mass participation is extracted. In other words, the sum of the effective masses in each direction should equal the total mass of the structure. But clearly, this depends on the number of extracted modes.

## How are mass participation factors related to vibrational energy?

As far as I know, a mass participation factor gives a representation of how much of the part is contributing to the eigenmode, or in other terms, how much vibrational energy is dissipated through the eigenmode. The infinite sum of the m.p.factors is equal to 1 or to another normalization quantity (e.g.