Q2. What are the types of gratings used in the revolution speed measurement?
Gratings can be geometrical notches with proximity transducers, magnetic patterns in the case of magnetic encoders or optical patterns with light sensitive transducers.
Q3. What is the first stage of the material removal?
In the first stage of this material removal, load or speed fluctuations due to the repetitive impacts of the moving components on the defect are diffuse but they grow as faults spread along the contact surface.
Q4. What is the use of the Pulse Timing Method?
Revolution speed measurement is performed with the help of the Pulse Timing Method largely used in gear Transmission Error measurement.
Q5. What is the promising investigation method for monitoring geared systems?
In the recent years, instantaneous angular speed becomes one of the most promising investigation way for monitoring geared mechanical systems [11, 15], internal combustion engines [16] or electrical motors [17].
Q6. How many frequency channels can be obtained from the FFT?
in order to increase the number of frequency channels, the signal length on which the FFT is performed must be as large as possible.
Q7. What is the advantage of angular sampling?
angular sampling makes it possible to Fourier Transform very large signals, giving access to high resolution spectral analysis and to the capability of sorting very low and close magnitude components.
Q8. What is the effect of the modulation effect on structural fixed resonances?
these established speed fluctuations act like modulating excitations on structural fixed resonances, leading to response signals with a very rich spectrum [6].
Q9. What is the effect of random slip of rolling elements on the shaft?
it is also assumed that random slip of rolling elements is negligible and frequencies are approximately located by equations (1)-(4) in reference to the rotation frequency of the shaft, with low differences due to load or actual kinematics.
Q10. What is the way to measure angular speed?
By the help of a large experimental investigation on two different applications, the authors prove that localized faults like pitting in bearing generate small angular speed fluctuations which are measurable with optical or magnetic encoders.
Q11. How can the authors estimate the frequency of an outer race fault?
From writing velocity relationships between bearing elements, the frequency location of an outer race fault can be estimated by equation (7).
Q12. What is the main reason for the enlargement of spectrum peaks in the case of double?
slip effects are also suspected to be at the origin of enlargement of spectrum peaks in the case of double row bearings loaded in a pure radial direction.
Q13. What is the alternative method of detecting faults?
This alternative way of detecting faults is based on instantaneous angular speed measurement by the help of optical or magnetic encoders.
Q14. What is the significance of the angular averaging process?
This signature does not affect the non-integer frequency channels associated with bearing faults and can be avoided by means of the angular averaging process.