Application of Four-Pole Parameters to Torsional Vibration Problems

1962 ◽  
Vol 84 (1) ◽  
pp. 21-34 ◽  
Author(s):  
C. T. Molloy
Keyword(s):  
Equivalent Circuit ◽  
Torsional Vibration ◽  
Natural Frequencies ◽  
Distributed Parameter Systems ◽  
Distributed Parameter ◽  
Torsional Vibrations ◽  
Electrical Circuits ◽  
Angular Velocities ◽  
Vibration Problems ◽  
Pole System

This paper deals with the application of the method of four-pole parameters to torsional vibrations. Results are developed from fundamental principles. The four-pole parameters for the basic rotational elements are derived. These include shafts (both lumped and distributed-parameter cases), disks, dampers, and gears. The equations which must be obeyed, when these elements are connected, are presented. The application to construction of equivalent electrical circuits is given and in particular a method for constructing the equivalent circuit of distributed-parameter systems is put forth. The torsional analogs of Thevenin’s and Norton’s theorems are given for rotational sources. The fundamentals mentioned above are then applied to the following problems: (a) The effect of substituting one four-pole for another in a torsional system. (b) The effect of opening a four-pole system and inserting a new four-pole between the separated four-poles. (c) Calculation of all the torques and angular velocities in a tandem system. (d) Calculation of natural frequencies of undamped four-pole systems.

Torsional Vibration Analysis of Drillstrings in Blasthole Drilling

2008 ◽  
Author(s):  
Omid Aminfar ◽  
Amir Khajepour
Keyword(s):  
Torsional Vibration ◽  
Natural Frequencies ◽  
Element Model ◽  
Drilling Process ◽  
Torsional Vibrations ◽  
Rotary Drilling ◽  
Well Drilling ◽  
State Response ◽  
Drilling Performance ◽  
Overall Performance

Reducing vibrations in well drilling has a significant effect on improving the overall performance of the drilling process. Vibrations may affect the drilling process in different ways, i.e., reducing durability of the drillstring’s elements, reducing the rate of penetration, and deviating the drilling direction. In rotary drilling, which is used to open mine and oil wells, torsional vibration of the drillstring is an important component of the overall system’s vibration that has received less attention in the literature. In this paper, we propose a finite element model for a sample blasthole drillstring used to open mine wells to investigate its torsional vibrations. Boundary conditions and elements’ specifications are applied to this model. In the model, the interaction between the insert and the rock is represented by a set of repetitive impulses according to the insert pattern. The steady-state response of the system to the repetitive impulses is found and natural frequencies, kinetic energy, and potential energy of the drillstring are calculated. The root mean square (RMS) of the total energy can be used as the measure for reducing the torsional vibration of the system. Finally, an optimum combination of inserts on the cone’s rows was found based on minimizing the total vibratory energy of the drillstring. The optimum design can reduce the torsional vibrations of the drillstring and improve the drilling performance.

Simulation of Torsional Vibrations or Multibody Simulation: Which Technique Does the Wind Power Industry Need for Solving the Present-Day Problems?

2003 ◽  
Author(s):  
Berthold Schlecht ◽  
Tobias Schulze ◽  
Jens Demtro¨der
Keyword(s):  
Torsional Vibration ◽  
Natural Frequencies ◽  
Wind Load ◽  
Operating Conditions ◽  
Drive Train ◽  
Torsional Vibrations ◽  
Multibody Simulation ◽  
Vibration Behavior ◽  
Drive Trains ◽  
Load Simulation

For the simulation of service loads and of their effect on the whole turbine the wind turbine manufacturers use program systems whose particular strengths lie in the wind load simulation at the rotor, in the rotor dynamics as well as in the control-technological operation of the whole turbine. The complex dynamic behavior of the drive train, consisting of the rotor, the rotor shaft, the main gearbox, the brake, the coupling and the generator, is represented as a two-mass oscillator. This simplification, which certainly is necessary within the framework of the wind load simulation programs, is by no means sufficient for the exact description of the dynamics of the more and more complex drive trains with capacities up to 5 MW. At first, the extension to a multimass torsional vibration model seems to be useful for the exact determination of the torsional vibrations in the drive train. However, in the turbines of all manufacturers there have been found forms of damage on drive train components (high axial loads in bearings, high coupling loads, radial loads on generator bearings) that cannot be explained even on the basis of a torsional vibration analysis. Moreover, in measurements on drive trains natural frequencies in the signals occurred that can no longer be explained by the torsional vibration behavior alone. Consequently, a real multibody simulation becomes necessary, for which also radial and axial vibrations can be taken into account, in addition to torsion, since these influence the torsional vibration behavior considerably. These dependences become already clear in an analysis of natural frequencies. This is illustrated by the example of a 700-kW turbine as well as by a planetary gearing for a 3-MW turbine. Especially in the dimensioning of the off-shore turbines with several MW output power, which are being planned, the use of multibody simulation will be advantageous, since the testing of turbine prototypes of this order of magnitude under the corresponding operating conditions are surely more cost-intensive and risky than the virtual testing with well validated simulation models.

scholarly journals Conceptual Control Method of Drilling Rig’s Torsional Vibrations Frequencies

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8403
Author(s):  
Tomasz Trawiński ◽  
Marcin Szczygieł ◽  
Bartosz Polnik ◽  
Przemysław Deja
Keyword(s):  
Torsional Vibration ◽  
Natural Frequencies ◽  
Control Method ◽  
New Technology ◽  
Drilling Process ◽  
Torsional Vibrations ◽  
Drilling Tool ◽  
Laboratory Facility ◽  
Drilling Method ◽  
Drilling Time

This article focuses on the possibility of using an innovative drilling method for the implementation of underground works, especially where there is no physical possibility of using large working machines. Work on a model carried out under the INDIRES project is discussed. A design of a drilling tool equipped with the proposed technology is presented. The solution in question makes it possible to increase the efficiency of the drilling process, which is confirmed by computer simulations. Also, introductory tests of a drilling process supported by torsional vibration generated by an electromagnetic torque generator provided in the KOMAG laboratory facility show the reduction of the drilling time by almost two-fold. In our opinion, adding torsional vibration acting on the plane of a drilled wall that equals natural frequencies of the drilled material represents a promising new technology for drilling. The presented work constitutes the basis for the development of the proposed technology and allows us to conclude that the developed method will be of great interest to manufacturers of drilling machines and devices.

scholarly journals Application of a Thermo-Hydrodynamic Model of a Viscous Torsional Vibration Damper to Determining Its Operating Temperature in a Steady State

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5234
Author(s):  
Wojciech Homik ◽  
Aleksander Mazurkow ◽  
Paweł Woś
Keyword(s):  
Torsional Vibration ◽  
Hydrodynamic Model ◽  
Operating Temperature ◽  
Operational Reliability ◽  
Point Of View ◽  
Model Verification ◽  
Torsional Vibrations ◽  
Vibration Damper ◽  
Drive Unit ◽  
Angular Velocities

The problem of damping torsional vibrations of the crankshaft of a multi-cylinder engine is very important from the point of view of the durability and operational reliability of the drive unit. Over the years, attempts have been made to eliminate these vibrations and the phenomena accompanying them using various methods. One of the methods that effectively increases the durability and reliability of the drive unit is the use of a torsional vibration damper. The torsional vibration damper is designed and selected individually for a given drive system. A well-selected damper reduces the amplitude of the torsional vibrations of the shaft in the entire operating speed range of the engine. This paper proposes a thermo-hydrodynamic model of a viscous torsional vibration damper that enables the determination of the correct operating temperature range of the damper. The input parameters for the model, in particular the angular velocities of the damper elements as well as the geometric and mass dimensions of the damper were determined on a test stand equipped with a six-cylinder diesel engine equipped with a factory torsional vibration damper. The damper surface operating temperatures used in model verification were measured with a laser pyrometer. The presented comparative analysis of the results obtained numerically (theoretically) and the results obtained experimentally allow us to conclude that the proposed damper model gives an appropriate approximation to reality and can be used in the process of selecting a damper for the drive unit.

The Geared Marine Oil Engine

1933 ◽  
Vol 125 (1) ◽  
pp. 461-492 ◽  
Author(s):  
C. H. Bradbury
Keyword(s):  
Torsional Vibration ◽  
Natural Frequencies ◽  
Complete Analysis ◽  
Historical Survey ◽  
Marine Oil ◽  
Worked Example ◽  
Vibration Problems

Although it is now more than ten years since the first geared oil engine installation put to sea, no country other than Germany has made any serious attempt to exploit this method of propulsion. The success of Germany's geared ships has, however, completely proved the reliability of this type of drive, and has exploded the once prevalent belief that mechanical reduction gearing would not withstand the uneven torque of the oil engine. The author first gives a brief historical survey of the geared oil engine ships at present in service, beginning with the original vessels of the Havelland class and finishing with Germany's “pocket” battleship Deutschland. The advantages of incorporating reduction gearing are then dealt with, the author maintaining that the disadvantage of added weight due to the inclusion of gears is more than compensated for by the advantages resulting from smaller engines running at higher speed. The types of drive in common use, namely, the rigid and the “Vulcan” types, are then described, together with the method of obtaining synchronized starting and reversing. It is pointed out that, although torsional vibration problems disappear to a large extent with the “Vulcan” drive, they are of extreme importance in the case of rigid drives. A complete analysis of the question is therefore made at the end of the paper, and expressions are obtained from which may be calculated the natural frequencies of the normal types of installation. A worked example is included to show the application of these expressions.

Computer Method for Forced Torsional Vibration of Propulsive Shafting System of Marine Engine With or Without Damping

1982 ◽  
Vol 26 (03) ◽  
pp. 176-189
Author(s):  
Jong-Shyong Wu ◽  
Wen-Hsiang Chen
Keyword(s):  
Torsional Vibration ◽  
Natural Frequencies ◽  
Computer Programs ◽  
Computer Method ◽  
Mode Shapes ◽  
Torsional Vibrations ◽  
Preliminary Design ◽  
Slide Rule ◽  
Output Data ◽  
The Mean

In the preliminary design of a propulsive shafting system, the additional (vibratory) stress due to torsional vibration is one of the important factors that must be considered in addition to the mean stress induced by the steady torque. In this paper, existing information concerning shaft design is reviewed; procedures formerly performed by slide rule, diagrams, and tabulations are formulated; and, based on the induced formulas, computer programs are developed. For an engine either two cycle or four cycle, single cylinder or multicylinder, and for a shafting system either undamped or damped (inner or outer or both inner and outer), it is required only to change the input data to obtain the desired data for various order numbers of torsional vibrations due to various firing orders of the cylinders. The output data include the natural frequencies and the corresponding mode shapes of the torsional vibrations, the amplitudes of twisting angles, and the vibratory stresses of the shafts. The reliability of the induced formulas and the developed computer programs has been confirmed by agreement between the computer output and existing information.

Adaptive Electromagnetic Torsional Tuned Vibration Absorber and its Application in Rotating Equipment

2012 ◽  
Author(s):  
Taher Abu Seer ◽  
Nader Vahdati ◽  
Hamad Karki ◽  
Oleg Shiryayev
Keyword(s):  
Natural Frequency ◽  
Torsional Vibration ◽  
Natural Frequencies ◽  
Vibration Reduction ◽  
Vibration Absorber ◽  
Torsional Vibrations ◽  
Wide Range ◽  
Simulation Results ◽  
Rotating Equipment ◽  
Tuned Vibration Absorber

Rotating equipment is susceptible to torsional vibrations whenever the RPM of the rotating equipment matches one of the torsional natural frequencies. For rotating equipment running at constant RPM, it is easy to control and mitigate the torsional vibrations, but in applications where the RPM is no longer a constant and varies widely or natural frequencies are changing: there is a need for a wide range vibration reduction device. In this paper, a translational adaptive electromagnetic tuned vibration absorber (ETVA) is described where its natural frequency is varied using electronics. The ETVA is modeled and its simulation results correlate very well with experimental results. Later, this concept is used to develop a torsional tuned vibration absorber (TTVA) device. The electromagnetic TTVA can be attached to rotating equipment to control torsional vibrations. The electromagnetic TTVA adapts itself and controls the torsional vibrations as and when the RPM varies. Here in this paper, the rotating equipment and the electromagnetic TTVA are modeled. Analysis results indicate that the torsional vibration of rotating equipment can be easily controlled using this newly developed electromagnetic TTVA.

A Comprehensive Torsional Vibration Analysis Procedure: Part I

1997 ◽  
Author(s):  
Mark A. Corbo ◽  
Stanley B. Malanoski
Keyword(s):  
Torsional Vibration ◽  
Vibration Analysis ◽  
Natural Frequencies ◽  
Gear Tooth ◽  
Design Procedure ◽  
Analysis Procedure ◽  
Lateral Vibration ◽  
Practical Design ◽  
Vibration Problems ◽  
Turbomachinery Design

Abstract One of the foremost concerns facing turbomachinery users today is that of torsional vibration. In contrast to lateral vibration problems, torsional failures are especially heinous since the first symptom of a problem is often a broken shaft, gear tooth, or coupling. The difficulty of detecting incipient failures in the field makes the performance of a thorough torsional vibration analysis an essential component of the turbomachinery design process. The aim of this paper1 is to provide users with a practical design procedure that can be used to ensure that their systems will not encounter major difficulties in the field. It has been the authors’ experience that most turbomachinery users encounter little difficulty in determining their machine’s natural frequencies due to the large number of resources available in that area. However, problems often arise when they must translate this information into an accurate prediction of whether or not their design will experience torsional vibration problems. Accordingly, this two-part paper concentrates on the steps that should be taken once the natural frequencies have been found.

Sign in / Sign up

Export Citation Format

Share Document