CVA Resonance & Structural Analysis

Question 1

What is resonance in the context of machinery vibration?

Accepted Answer

A condition where an excitation frequency coincides with a system natural frequency, causing amplified vibration response

Answer

A condition where structural damping exceeds the forcing frequency

Answer

A measurement technique for identifying bearing defect frequencies

Answer

The maximum vibration amplitude allowed by ISO standards

Question 2

What is a natural frequency (also called resonant frequency)?

Accepted Answer

The frequency at which a system vibrates freely after an initial disturbance, determined by its mass and stiffness

Answer

The frequency range across which a sensor responds uniformly

Answer

The running speed frequency of the machine during normal operation

Answer

The frequency at which bearing defects are most likely to occur

Question 3

What is the damping ratio, and how does it affect vibration at resonance?

Accepted Answer

The ratio of actual damping to critical damping; lower ratios produce higher amplitude amplification at resonance

Answer

The ratio of resonant frequency to operating frequency; determines whether resonance occurs

Answer

The fraction of vibration energy converted to heat per cycle; affects only high-frequency components

Answer

The ratio of stiffness to mass; determines the natural frequency of the system

Question 4

What is a mode shape in structural dynamics?

Accepted Answer

The pattern of deformation that a structure exhibits when vibrating at a specific natural frequency

Answer

The frequency spectrum shape at a structural resonance

Answer

The waveform shape of the vibration time signal during resonance

Answer

The shape of the frequency response function peak at resonance

Question 5

What is a frequency response function (FRF) used for in structural analysis?

Accepted Answer

Calculating the ratio of output response (vibration) to input force as a function of frequency, used to characterize system dynamics

Answer

Measuring the amplitude of each harmonic in a rotating machine spectrum

Answer

Comparing vibration levels at different operating speeds

Answer

Determining bearing defect frequencies from geometry

Question 6

What is experimental modal analysis (EMA) used for?

Accepted Answer

Determining a structure's natural frequencies, mode shapes, and damping ratios from measured vibration responses

Answer

Continuously monitoring bearing condition during machine operation

Answer

Balancing a rotor to a specified ISO quality grade

Answer

Setting alarm limits for machinery vibration monitoring programs