Pdf experimental investigation of shaft whirl carrying 3. Calculation of propellerexcited whirling critical speeds. The purpose of this paper is to present an approach for replacing the effects of each rigid disk mounted on the spin shaft by a lumped mass together with a frequencydependent equivalent mass moment of inertia so that the whirling motion of a rotating shaftdisk system is similar to the transverse free vibration of a stationary beam and the technique for the free vibration analysis of a. Whilst investigating the effects of rotor unbalance on the critical whirling speed, it was observed that when the oil supply to the bearings was cut off, the mode and amplitude of vibration. Find out more about the whirling of shafts and crit. The effect of the shaft diameter and torsional stiffness on the whirling speed of the ship propeller shafting system. The problems associated with shaft whirling have already been discussed by the author in a previous report 1, and preliminary experiments have been carried out on a model rig s, confirming the fundamental theory of shaft whirling. Experimental study on whirling, flying and tilting motions. A movable cord plate allows students to control the shaft in some experiments, to help reach the second mode whirl speed. Critical speed of shaft or whirling of shaft 1421 5. Whirling of shaft mech2420 engineering mechanics uon. Frequencies at different speeds for various shaft diameters are evaluated and compared.
Whirling of shaft whirling of shaft aim to determine the. Whirling of shafts when a shaft rotates, it may well go into transverse oscillations. Experimental investigation of shafts on whirling of shaft. When the same happens to a rotating shaft, it is called whirling. Tm1001 whirling of shafts and critical speed description tecquipments whirling of shafts apparatus tm1001 shows how shafts vibrate transversely and whirl at a certain rotation frequency. Introductio n in engineering, we have seen many applications of shaft and a rotor system. Summary due unbalance in a shaftrotor system, rotating shafts tend to bend out at certain speed and whirl in an undesired manner whirling is defined as the rotation of plane made by the bent shaft and line of centers of bearings theoretically, the deflection of the shaft tends to infinity when r 1, i. Power transmitting shafts always have either gear, pulley, sprocket, rotor or a disc attached to a shaft as shown in the figure. Cam are mounted on the end of a shaft driven by a variable speed motor. Full text of on the whirling and vibration of shafts. Experimental and analytical investigation of propeller. Now if you pluck the string, it moves in a transverse direction. Investigating the whirling speed of an unloaded shaft rigidly fixed at both ends.
This research develops an experimental method to measure the motion of a fdb spindle system with a 3. Name of experiment date of performance experiment marks teachers. The critical speed ncof a shaft is simply where m the mass of the shaft assumed concentrated at single point. The centre of gravity of the weight is displaced by an amount e from the axis of the rotation. Our analysis service helps you eliminate the risk of costly bearing failures, shaft fractures or structural damage resulting from harmful vibrations. Our experts provide natural frequency and forced vibration analysis of both axial vibrations and lateral whirling vibrations. When the shaft rotates at a speed equal to the natural frequency of transverse oscillations, this vibration becomes large and shows up as a whirling of the shaft.
The equipment is in two parts and fits on a bench or desktop. Experimental and numerical studies of whirling fires by james anthony marsden beng, ceng, fifiree, me. A thesis submitted to the faculty of design and technology in partial flulfilment of the requirements for the degree of doctor of philosophy university of. Since the fundamental bending natural frequency of a onepiece drive shafts made of steel or aluminum is normally lower than 3800 rpm when the length of the drive shaft is around 2 m, the steel drive shaft. Proceedings of the 1st international and 16th national conference on machines and mechanisms inacomm20, iit roorkee, india, dec 1820 20 control of whirling of a rotating shaft using hslds mountings siddhartha bhowmick department of mechanical engineering kanksa academy of technology and management, tig. This critical whirling speed is dependent on the shaft dimensions, the shaft material and the shaft loads. The frame will support motor, sliding block and shafts. This paper deals with the study of whirling of shaft with three rotors. Much of this analysis is based on linear or linearised models of the rotor, bearings and supports, where the whirling of the shaft results from an eccentricity between the centre of mass and the geometrical centre of the rotor. A sensor at the driven end measures the shaft speed and sends its signal to the control and instrumentation unit display. The operation of the whirling of shafts unit meer unit starts when the potentiometer of the console is activated. The critical speed of a twobearingshaft rotor system is shown to depend upon rotor unbalance for bearings of normai clearance. On completion of this tutorial you should be able to do the following. The free undamped vibration calculations are available in this application.
Critical or whirling or whipping speed is the speed at which the shaft tends to vibrate violently in transverse direction. Tecquipments whirling of shafts and critical speed apparatus tm1001 shows how shafts vibrate transversely and whirl at a certain rotation frequency. G of the rotating masses from the axis of rotation of the shaft. It also shows that the whirling, flying and tilting motion converge very quickly to the steady state at the same time when the rotor reaches. Analytical solution for whirling speeds and mode shapes of. Theoretical and experimental studies of whirling speeds of. Jabbar firouzi, hassan ghassemiand, the effect of the shaft diameter and torsional. Whirling of shafts force applied and interdisciplinary.
Design validation of experimental values is done by comparison with theoretical outputs. Design,and,analysis,of,drive,shaft,for,heavy,duty,truck. Critical speed experiment critical speed of a beam in a lathe. Experiments are described which show the effects of bearing length, bearing clearance, and lubricant viscosity on the critical whirling speeds of a singleshaft rotor system supported in plain bearings. For this purpose, four experiments were carried as shown in fig. Control of whirling of a rotating shaft using hslds mountings. Since you know the term whirling, i guess you are aware of the unbalanced forces that are present in a rotating shaft. Teaching equipment theory of machines whirling of shafts. Determination of critical speed of whirling of shaft. Pdf experimental study of effect of eccentricity on. Investigating the whirling speed of a loaded shaft. This helps engineers understand possible problems with long shafts and allow for them in their designs.
The effect of the shaft diameter and torsional stiffness. The whirling vibration application is able to check the shaft line for vibrations due to the rotation of the shaft line and the hydrodynamic effects of the propeller. Thanks to this unit the speeds to which a shaft may or may not operate are determined. Mechanics of machinesii lecture no48 critical speed of. Whirling of shafts with damping the deflection of shaft is. The speed at which the shaft start to vibrate violently in the direction perpendicular to the axis of the shaft is known as critical speed. Ever held any rope at its two ends and rotate it, like skipping. The drive unit consists of a dc motor connected to the shaft through v belt.
If the shaft is out of balance, the resulting centrifugal force will induce the shaft to vibrate. Whirling is usually associated with fastrotating shafts. Theoretical studies have been carried using patran to determine the natural frequencies and the mode shapes for the jeffcot and kikuchi rigid rotor. Two movable nylon bushes help to prevent the shaft whirling amplitude from reaching excessive levels.
Design and analysis of drive shaft for heavy duty truck. Non contact type tachometer, whirling shaft setup, scale theory. Lateral vibration prediction issues shaftdesigner co machine support b. It is defined as the speed at which a rotating shaft will tend to vibrate. Whirling of shafts application in industry crusher mills. A uniformly loaded shaft may be made to vibrate transversely in just the same way as a shaft, which carries a single concentrated load or disc. Whirling speed is also called as critical speed of a shaft. The whirling characteristics of the shaftrotor system rotating in dry bearings. To study the effect of different sizes and end conditions on whirling speeds. Destroyed white metal liner of the stern tube bearing is shown fig.
Whirlingspeed is also called as critical speed of ashaft. The critical speed is the same as the frequency of traverse vibrations. The design of various components of experiment is discussed in detail. Whirling speed of shafts theory of machine subscribe our new channel gate academy global now. Introduction the cam analysis machinecam has been designed to enable students. Whirling of shaft or critical speed of the rotating shaft duration. Solid mechanics dynamics tutorial forced vibrations this work covers elements of the syllabus for the engineering council exam d225 dynamics of mechanical systems and c105 mechanical and structural engineering. It is defined as the speed at which a rotating shaft will tend to vibrate violently in the transverse direction if the shaft rotates in horizontal direction. From the above equations, it is clear that the natural frequency is a function of the string length and does not depend on the mass of the pendulum. Whirling of shafts introductio n shaft problems in shaft and a rotor systems. Bland langley research center langley station, hampton, vd. Critical speeds of shafts study notes for mechanical. Whirling of a shaft is its movement in a direction transverse to the axis of rotation.
Shaft whirling and axial vibrations analysis dnv gl. The objective of this paper is to determine the whirling bending critical speeds of pultruded composite shafts in simply supported boundary conditions. The dynamics of rotating machinery, and in particular the response to outofbalance forces and moments, is well established. A compact bench top mounting experiment to demonstrate the phenomena of whirling shafts from tecquipment.
374 211 1000 161 412 991 512 912 836 106 291 1603 533 1403 1599 699 423 649 823 318 1082 825 973 1573 930 913 177 1240 1625 317 215 618 187 1396 554 651 557 819 862 1281 689 484 652 1239