A HANDBOOK ON TORSIONAL VIBRATION PDF
The memberslnp of the Torsional Vibration Panel is drawn from mem- ber .. from member firms or at the B.I.C.E.R.A. Labora- tory, is included in this handbook. PDF | This paper reports on a study of the crankshaft torsional vibration phenomenon in An analysis of the torsional vibrations indicates the dynamic loading on each Nestorides, E. J. (Ed.) A handbook on torsional vibra-. A torsional vibration model of a V20 spark-ignited gas engine was developed and validated with Keywords torsional vibration, speed measurement, multi- body dynamics, Harris' shock and vibration handbook (6th ed.).
|Language:||English, Spanish, French|
|Genre:||Science & Research|
|ePub File Size:||16.74 MB|
|PDF File Size:||19.65 MB|
|Distribution:||Free* [*Registration Required]|
to determine the natural frequencies of torsional vibrations, mode shapes, critical speed and Torsional vibration analysis of six cylinder diesel engines. 4. of mechanical vibration, particularly torsional vibration. Despite these gaps in their ling the problem of torsional vibration in aircraft engines were numerous and “A Handbook on Torsional Vibration,” compiled by E.J.. Nestorides of the . Keywords: torsional vibration, torsional damper, crank train, crankshaft, multi- body system. 1. Introduction. Torsional vibration is common to internal- combustion engine crankshafts. ..  Nestorides E. J. A Handbook on Torsional Vibration.
Periodically changing gas and inertia forces occurring in piston combustion engines generate transvers vibrations, axial vibrations, torsional vibrations which produce changeable deformations Wojciech, Vibration on the ship can be a root to many problems and some issues on damage or failure can manifest as vibration.
Principle of superposition is valid in this case Dwivedy, Torsional vibration is twisting of the crank from one end to the other. It happens at fairly high frequencies and is driven by two different uneven torque pulses coming from the pistons Sisco, Any elastically coupled shaft or other system will have one or more natural frequencies which, if excited, can build up to an amplitude which is perfectly capable of breaking crankshafts.
The essence of control is to adjust these two parameters, q and J or s and m , to achieve a frequency which does not coincide with any of the forcing frequencies Wang, Causes and Consequences of Vibration.
Redpath, Some of the wave energy is transferred to the hull causing main hull and local vibrations Tupper, The effects of the damage of torsional vibration on propulsion shaft is shown in the figures on the overleaf. Treating Torsional Vibration.
There are quite a few possible ways of dealing with torsional vibration and minimizing the effects on the propulsion system of a ship. This can be done both during the design phase of the ship building and also during operational life of the vessel. The vibration of ship machinery is well understood and can be predicted with sufficient accuracy.
This confidence in the calculations is needed to be sure that the vibration levels will remain below the corresponding admissible limits. It is important that vibration aspects are considered at the earliest stage possible in the ship design process to find a cost-effective installation with the best combination of countermeasures against vibration. Some ideas are briefly discussed below: a The first step in analytically determining the torsional response is to calculate the torsional natural frequencies of the system.
To do this requires the stiffness and mass inertia of the shaft and components being analysed referred to as the mass-elastic data. For cylindrical shafts, the mass moment of inertia and torsional stiffness can be calculated using simple formulas. These dampers are normally intended to protect the engine crankshaft and not necessarily the driven machinery.
Designers nowadays can carefully adjust the resonance frequency, the forcing impulses and resultant stresses by adjusting shaft sizes, number of propeller blades, crankshaft balance weights and firing orders of the engine cylinders Woodyard, In critical cases, vibration neutralizers can be fitted in the form of sprung and damped weights which absorb energy or active systems can be used generating forces equal in anti-phase to the disturbing forces Tupper, Out-of of balancing forces and couples relate to revolving masses and reciprocating masses Wang, This is essential in order to have machinery that operates safety and reliably.
The wrong combination of individually satisfactory components may lead to an inappropriate system. Identifying the interaction between components, which the Nauticus Machinery Torsional Vibration calculation software can do, is an essential part of the system and functionality assessment DNV GL, Problem: Engine crankshaft failure.
Cause: Seized engine damper due to improper maintenance. Solution: Installed and properly maintained damper. Upon inspection, it was determined that the damper located on the non- drive end of the engine crankshaft was seized. The silicon fluid was solidified and black from heat and age.
It was in effect a solid flywheel without any damping properties. After the engine was overhauled and the damper was replaced, field tests were performed to determine if there was a dangerous resonance within the operating speed range. Torsional measurements were also taken at the flywheel and bull gear with frequency modulation non-contacting probes. Torsional natural frequencies were measured at These natural frequencies were intersected by various engine excitation orders within the speed range.
The forced response was calculated by considering the dynamic torque produced by the engine and evaluating the properties of the engine damper. The actual pressure-time curves from each cylinder were measured and combined with the inertial effects of the reciprocating weights. Rough engine operation caused increased torque modulation at certain orders; therefore damaging torsional vibration could occur if the engine was not well tuned.
From the field data and analytical work, it was determined that the crankshaft failure was caused by the 4.
The alternating shear stress in the crankshaft was highest on resonance near RPM and was excessive without a properly functioning engine damper. The third torsional natural frequency was primarily a crankshaft mode, resulting in maximum twisting at the failure location of the crankshaft.
Catamaran vessel operation: Significant vibration motions in some operating modes. Problem Description: During the exploitation of the catamaran ferry significant torsional vibrations have been noticed.
At the same time, the temperature of flexible torsional coupling, located between the main propulsion engine and the reduction gearbox, increased. Significant vibrations occurred in two operating modes, i. The considered ship is a two-screw catamaran ferry equipped with the two independent propulsion systems.
Preliminary results show the following problems: the shaft line was not aligned properly so the bearing sleeve did not wear uniformly; bearings had large clearances causing significant lateral vibrations increasing thus coupled lateral and torsional vibrations dynamic response; the resilient mounting of main engines was not properly executed; keeping in mind the type of bearings and the type of shaft line setting, the shaft line seemed to be too stiff; the stern structure of the ship was not as stiff as it should have been; the main engine governor operation was not smooth, and the governor had inappropriate regulation characteristics.
Although some of the above listed shortcomings had been eliminated, torsional resonance occurred again, but in a different rpm range. The trouble was that the occurrence of resonance still remained within the operating range of the main propulsion engines.
Bearing in mind the above mentioned phenomena, measurements conducted in service were required to investigate the problem fully. Measurement: Three measurement programs have been established, i. Measurements were performed by the Brodarski Institute, Zagreb.
Program A is the initial testing program when the ship is in a seaport. The main engines are running until the operating temperature is achieved, and the range of engine speed is being changed from rpm to rpm with increments of rpm.
After each increment, stabilization is necessary, taking one minute. The propeller shafts are disconnected and the auxiliary engines are running intermittently. Program B is the normal operating mode of the ship when the ferry sails on its route.
Program C follows after Program B has been executed and it is done for the free operating mode, i.
The influence of oil level in the governor box on the vibration amplitude and frequency of the regulation bar for fuel dosage is analysed immediately after resonance has occurred. The main propulsion engine is instantly turned off and a specific volume of oil approximately 0.
Subsequently, the main propulsion engine is switched on and the propulsion system is reverted to the operating mode in which the torsional vibration resonance occurred. Measurement of regulation bar motion indicates the influence of oil level decrease in the governor box on the main propulsion engine governor behaviour as well as on the behaviour of the whole propulsion system.
The measurement of the oil temperature and pressure in the engines and gearbox systems is carried out by using the same instruments which the ship crew uses during the regular measurement and control of these parameters Conclusion: Issues related with the torsional vibration resonance of a catamaran ferry have been investigated, and due to propulsion system complexity full scale measurement seemed to be the best approach to this challenging problem.
The investigated problem shows that proper design of the ship propulsion system is not sufficient for reliable ship operation. Moreover, it is very important to maintain the ship properly in exploitation because non- typical causes of vibration which cannot be detected easily can cause severe damages to the propulsion system.
Nikola, et al. Conclusion For the assessment of ship vibration performance, the actual vibration levels at the most critical locations are to be measured and evaluated during the sea trials.
Excessive ship vibration is to be avoided for passenger comfort and crew habitability. In addition to undesired effects on humans, excessive ship vibration may result in the fatigue failure of local structural members or malfunction of machinery and equipment America Bereau of Shipping, Over the years corporate bodies, scholars, ship construction dock yards as well as the International Maritime Organization IMO and classification societies have all at different times being involved in and carried out a lot of research projects carried out on the propulsion system of various ships and marine vessels to understand the concept of vibration on shafting systems, the consequent damage and control.
Torsional vibration is often a concern in power transmission systems using rotating shafts or couplings where it can cause failures if not controlled.
As a rule, capacity control is determined by the compressor discharge pressure. Originally published in , this book was primarily written to provide information on torsional vibration for the design and development departments of.
A Handbook on Torsional Vibration. In addition to promoting obtaining the Certificate in Structural Engineering, we also welcome auditing of courses:. DATS is a comprehensive package of data acquisition, signal processing and reporting tools. The model includes flexible elements; therefore, torsional vibrations can be.
This paper reports on a study of the crankshaft torsional vibration phenomenon in internal combustion engines. In clearance fits, the coupling bore is sized so the shaft will slide snugly but freely into the hole. Ling the problem of torsional vibration in aircraft engines were numerous and.
A second effect of torsional vibrations applies to passenger cars.
PDF generated on Jan- Guideline not under Configuration Control Cryogenic Handbook This document provides guidance, reference, specific information, requirements and.
Minimum Recommended Experience: 6 months. Torsional vibrations can lead to seat vibrations or noise at certain speeds. The steady state of the state equation is solved. Category I Vibration Analysts are qualified to perform a range of single channel machinery vibration condition monitoring and diagnostic activities including data acquisition on predetermined routes, machine steady state testing to predefined procedures, and comparison of readings against pre- established alert settings.
The most prevalent reason is to adjust the suction flow to match the process demand. There DATS Toolbox provides the basic functionality and many analysis tools and there are a number of add- on options that address particular types of measurement and.
Handbook of Torsional Vibration, Cambridge. In the paper, the torsional vibrations of marine power transmission system' s nonlinear method have. View and Download Polaris Sportsman service manual online. Makes the performance of a thorough torsional vibration analysis an essential.
A handbook on torsional vibra-. Bibliography[ edit]. Quite simply, coupling is the transfer of energy from one medium to another, for example, from a metallic wire to an optical cable.The measurement of the oil temperature and pressure in the engines and gearbox systems is carried out by using the same instruments which the ship crew uses during the regular measurement and control of these parameters Conclusion: Issues related with the torsional vibration resonance of a catamaran ferry have been investigated, and due to propulsion system complexity full scale measurement seemed to be the best approach to this challenging problem.
Page 1 There are two main reasons why compressor capacity regulation is used. Today, the FEM is the ence , which is known as the BICERA method, most widely used method for determining the tor- modernized by computer support in reference , sional stiffness coefficient. The method analysing the crank torsional stiffness coefficient determination has been given in the literature. This leads email: Reeds Marine Surveying.