Frequency response of Torsional Vibration

In summary, the project involves measuring the natural frequency of torsional vibration in a system consisting of two rotors, a shaft, and bearings. The procedure includes using accelerometers, software, and an impact hammer to compare the lateral and torsional frequency response functions. The validity of the procedure is confirmed and additional literature and advice are provided.
  • #1
muharifiandi
1
0
Hello engineers!
I have a project to measure/ obtain natural frequency of torsional vibration. Below is the detail:

1. Object measurement:

Two rotor attached to one shaft and the shaft is supported by two bearing. The shaft is connected to a motor. I give the scheme below.

2. Equipment: two accelerometer, one pc/laptop include software to measure frequency response function (frf), one acquisition data machine, one impact hammer

3. Procedure

3a. First, I measure lateral frf (ordinary frf/ translasional frf). I give impact in the two holder (that has bearing).

3b. Second, I measure torsional frf by give impact in rotor so it will be like that I give torque to the system.

3c. We compare the result 3a and 3b and look to frequency where has high amplitude in 3b (torsional) but not in 3a (lateral). So the frequency is torsional natural frequency.
My question is:

1. Is my procedure valid?

2. Can you give me some literature that related to my project?

3. What is your advice and tips to my project?

http://mechanical-engg.com/forum/uploads/monthly_2015_11/torq.PNG.80d4fa9613b4f538e41024dcb50494ef.PNG Sorry for my english

Thanks for answering my question!
 
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  • #2
1. Yes, your procedure is valid.2. Here are some resources that may be helpful:-Natural Torsional Vibration Analysis of Shafts in Rotating Machinery by S.A. Amabili-An Introduction to the Finite Element Method for Differential Equations by Peter W. Glynn and George F. Pinder-Nonlinear Dynamics and Chaos by Steven Strogatz-Vibration of Mechanical Systems by Ali H. Nayfeh3. My advice is to make sure you have all the necessary equipment and to familiarize yourself with the concepts and methods related to your project, such as finite element analysis and nonlinear dynamics. Also, consider testing the system with different loads and speeds to get a better understanding of the system's behavior. Finally, make sure to document all of your findings and results.
 

1. What is torsional vibration?

Torsional vibration is a type of mechanical vibration that occurs in rotating systems, such as engines or turbines. It is caused by the twisting or bending of the shaft, and can lead to undesirable effects such as increased stress and wear on the components.

2. How is frequency response of torsional vibration measured?

The frequency response of torsional vibration is typically measured using a torsional vibration analyzer, which consists of a sensor attached to the shaft and a data acquisition system. The analyzer records the amplitude and frequency of the vibrations, which can then be used to determine the system's natural frequencies and resonant points.

3. What factors affect the frequency response of torsional vibration?

The frequency response of torsional vibration can be affected by various factors, including the stiffness and damping of the shaft, the mass distribution of the rotating components, and the speed of rotation. Changes in these parameters can alter the natural frequencies of the system and influence its response to external forces.

4. How does torsional vibration impact the performance of rotating systems?

Torsional vibration can have a significant impact on the performance of rotating systems. It can cause excessive noise and vibration, which can lead to component failure and reduced lifespan. It can also affect the accuracy and stability of precision equipment, such as turbines used in power generation.

5. How can torsional vibration be controlled or reduced?

There are several techniques that can be used to control or reduce torsional vibration, including modifying the stiffness and damping of the shaft, balancing rotating components, and using vibration isolation mounts. Additionally, accurate prediction and analysis of the system's natural frequencies can help to avoid resonance and minimize vibration levels.

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