## How do you read FRF?

The real part of the FRF will equal zero at natural/resonant frequencies….The six FRFs are located as follows:

1. Measurement points 1 and 3 are on one end of plate.
2. Measurement points 7 and 9 are in the center.
3. Measurement points 13 and 15 are on the other end, opposite points 1 and 3.

## What is the magnitude of frequency?

Magnitude-frequency relationship is a relationship where events with a smaller magnitude happen more often than events with large magnitudes. For rainfall phenomena both small magnitudes as well as large magnitudes may be catastrophic as illustrated in figure 1.

How do you determine dynamic stiffness?

The dynamic stiffness Km is calculated by dividing f2 by the magnitude of H1(f) . Here, f is the frequency value.

### What is FRF phase?

The frf is a plot of the amplitude and phase-lag of a particular floor of a building as a function of the forcing frequency. The first part of the frf is the plot of amplitude versus frequency. At resonant frequencies, the frf will have a sharp peak.

### What is Modal Analysis in vibration?

Modal analysis is the study of the dynamic properties of systems in the frequency domain. Examples would include measuring the vibration of a car’s body when it is attached to a shaker, or the noise pattern in a room when excited by a loudspeaker.

What is frequency response in vibration?

Definition. A Frequency Response Function (FRF) is a function used to quantify the response of a system to an excitation, normalized by the magnitude of this excitation, in the frequency domain.

#### What is the relationship between magnitude and frequency of earthquakes?

The frequencies of earthquakes increase exponentially with decreasing magnitude in Figure 2. The asymptotic trends of the curve at extreme values of magnitude and frequency give it a sinusoidal shape. This is typical of the relationship between magnitude in terms of energy released and frequency of natural hazards.

#### What is the difference between static and dynamic stiffness?

Static stiffness is the response of part loaded at close to 0 hertz (frequency) called quasi – static stiffness. A part can have a no. of dynamic stiffness at various frequencies but only one static stiffness. Dynamic stiffness is closely related to the fundamental frequencies or modes of the part.

What does dynamic stiffness mean?

Dynamic stiffness, or impedance, is the ability of the actuator to resist an external oscillatory load. Dynamic stiffness requirements are defined in the hydraulic actuator specification as boundaries within which the measured impedance must be located.

## What is modal amplitude?

It describes the capacity of each mode to absorb energy and to generate squeal. This method was applied on an academic system and gave good prediction results. A second strategy is the Modal Amplitude Stability Analysis (MASA) developed by Nacivet and Sinou  in the case of mono-instability.