CVA Bearing Analysis & Fault Detection 3

Question 1

What is the primary advantage of using acceleration for high-frequency bearing analysis compared to velocity?

Accepted Answer

Acceleration is more sensitive to high-frequency impulsive events that characterize early-stage bearing faults

Answer

Acceleration sensors are less expensive than velocity transducers

Answer

Acceleration measurements do not require transducer mounting corrections

Answer

Acceleration signals have lower noise floors than velocity signals

Question 2

Which bearing defect frequency is most affected by shaft speed variation?

Accepted Answer

All bearing defect frequencies scale linearly with shaft speed

Answer

FTF (cage frequency)

Answer

BPFO (outer race frequency)

Answer

BPFI (inner race frequency)

Question 3

What does 'bearing clearance' affect in terms of vibration characteristics?

Accepted Answer

Load distribution, contact stress, and vibration amplitude; excessive clearance increases vibration and reduces bearing life

Answer

Only the frequency of bearing defect components

Answer

Only the lubrication film thickness within the bearing

Answer

The balance grade required for the rotor

Question 4

In rolling element bearing failure analysis, what does 'spalling' refer to?

Accepted Answer

Fatigue cracking and flaking of material from bearing raceways or rolling element surfaces

Answer

Uniform wear of the rolling element contact surfaces

Answer

Corrosive pitting due to moisture contamination

Answer

Plastic deformation of the inner race from overloading

Question 5

What is the typical shape of a shaft orbit for a machine running with pure rotor unbalance?

Accepted Answer

A circular or slightly elliptical loop rotating at 1× shaft speed

Answer

A figure-eight (Lissajous) pattern

Answer

An irregular, noisy cloud of data points

Answer

A straight line oriented along the bearing load direction

Question 6

What does the term 'bearing frequency' BPFI typically equal for a standard bearing with 8 balls at 1800 RPM (30 Hz shaft speed) and a pitch diameter to ball diameter ratio where Bd/Pd cosθ ≈ 0.3?

Accepted Answer

Approximately 4.9× shaft speed

Answer

Approximately 5× shaft speed

Answer

Approximately 3.1× shaft speed

Answer

Approximately 2.8× shaft speed