Effect Of Torsional Vibration Research Articles

Coupled vibration characteristics of marine shafting with complex change of inclination under ice loads

With the intensifying exploitation of the resources and the waterway of the Arctic region in worldwide, the variable inclination propulsion system are gradually used in the ice-sailing ship, its design and strength study are of great engineering significance and application value. A variable inclination propulsion shafting with universal joint is introduced and its mechanical model is established in this paper. By combine torsional stress and inclination angle calculation, a decoupling algorithm based on Newmark is designed, and then the analysis of ice loads response in both frequency domain and time domain are completed. The results show that due to the complex triangle function relation among the various components of the shafting, there is an interaction between the propeller and the transmission shafting. In particular, when considering the dynamic change of inclination, nonlinear bending-torsional coupling vibration may occur and further lead to the enhancement effect of torsional vibration. Among the three working conditions defined by DNV, the bending-torsional coupling effect vary with rotation speed and inclination angle, and is mainly concentrated in high frequency bands. In the ice loads condition 2, with the largest time domain excitation amplitude and the smallest high order component, it’s vibration response is the strongest, and the change law of dangerous phase angle is similar to the bending moment. With the increase of initial inclination angle, the amplitude of low frequency vibration decreases, yet the amplitude of high frequency vibration increase. This trend is more obvious with the increase of rotation speed, and more high frequency resonance points appear in the condition 1 and condition 3.

Experimental investigation of drillstring torsional vibration effect on rate of penetration with PDC bits in hard rock

Polycrystalline diamond compact (PDC) bits have shown tremendous performance compared to roller cone bits and have gained attraction in deep geothermal drilling applications. While PDC bits can reach a higher rate of penetration compared to other bits, they are more prone to drilling vibrations. The scope of this paper is to quantify the effects of drillstring torsional vibrations on PDC bit performance using a laboratory testing facility. The tests were performed with three drillstring configurations to evaluate the effect of drillstring vibrations. The results showed that rigid testing overestimates the bit rate of penetration by 35% due to torsional vibrations.

Dynamic modelling and control of flexible link manipulators: methods and scope- Part-1

Objectives: This paper addresses two key issues in the area of flexible robotics. The issues are dynamic modelling and control of flexible link robots. A brief, yet, significant review is provided that addresses these issues. Methods: The various approaches used by researchers for dynamic modelling and control of flexible robots are presented. Besides that, methods used for achieving optimal control are also discussed. Findings: After a review of 153 research papers from the year 1975 to 2021, it has been found that a good dynamic model of flexible manipulator helps in reducing the control and computational efforts. Recent trends in research in the area of flexible manipulators are towards the use of sliding mode control and vision-based control techniques. Novelty: Inclusion of the effect of torsional vibrations besides lateral vibrations on the positional accuracy of flexible manipulators makes the current research work novel. Keywords: Flexible manipulator; modelling; dynamics; control

The Effect of Torsional Vibration in Longitudinal-Torsional Coupled Ultrasonic Vibration-Assisted Grinding of Silicon Carbide Ceramics.

Rotary longitudinal–torsional coupled ultrasonic vibration-assisted grinding (LTUAG) is a new manufacturing method that can improve the grinding ability of silicon carbide ceramics. However, compared with longitudinal ultrasonic vibration-assisted grinding (LUAG), the role of torsional vibration in the grinding process is unclear. In this study, an effective method for measuring longitudinal–torsional coupled ultrasonic vibration amplitude and an experimental setup for measuring actual amplitude during grinding are proposed. The trajectory of the abrasive grains under the same grinding parameters and the same longitudinal amplitude during LTUAG and LUAG are analysed. Ultrasonic amplitude curves under the condition of tool rotation are then measured and analysed. Finally, the effect of torsional vibration on grinding force and surface roughness under the same grinding conditions is explained. Experimental analysis shows that the introduction of torsional vibration has little effect on the trajectory length and does not change the number of interference overlaps between abrasive grain tracks. Torsional vibration will only increase the cutting speed during grinding and reduce the undeformed chip thickness, which will reduce the grinding force and improve the surface roughness of LTUAG.

Analysis of torsional vibration effect on the diesel engine block vibration

In this paper, the coupling effect between the crankshaft torsional vibration and the low speed diesel engine block vibration is investigated. Using finite element method (FEM), a model of low speed diesel engine is established to study the vibration response. The mode results of FEM agree very well with the test. The additional torques acting on the low-speed diesel engine caused by torsional vibration are discussed in detail. The vibration response of the low-speed diesel engine considering the effect of torsional vibration is studied using FEM simulation. By analyzing the effect of torsional vibration, the results demonstrate that the crankshaft torsional vibrations have important effects on the engine block vibration. The results from this study can provide useful theoretical guidance to predict vibration of low-speed diesel engine.

Effects of torsional vibration of a propulsion shafting system and energy efficiency design index from a system combining exhaust gas recirculation and turbocharger cut out

Recently constructed vessels are equipped with super long stroke engines to accommodate stiffer environmental regulations and to reduce fuel consumption. This is a way to reduce fuel consumption in main engines for propulsion by improving propeller efficiency and thermodynamic efficiency of the engine. However, ships intended to accommodate nitrogen oxides regulations must satisfy the Tier III regulation prescribed by the International Maritime Organization. For this purpose, the vessel should apply additional nitrogen-oxide reduction facilities. When an exhaust gas recirculation (hereafter EGR) system is applied for the exhaust gas reduction, not only is the fuel consumption increased according to the amount of EGR, but the vibration excitation force tends to increase as well. In addition, there is a limit to the engine control technology that can be applied to optimize fuel consumption under partial load, even if the ship travels in areas other than NOx emission control areas, the fuel consumption of the engine is high. Therefore, it is necessary to change the design of the ship so that fuel can be saved even in areas other than NOx emission control areas by applying the turbocharger cut out (hereafter TCCO) method. In this paper, the performance and dynamic characteristics of a marine diesel engine were compared and reviewed when applying a combined system of EGR and TCCO. Also examined were effects on the torsional vibration of a corresponding propulsion shafting system and the energy efficiency design index (hereafter EEDI) according to each operating condition of the engine applied with this system.

A Modified Approach for Torsional Vibration Analysis of Some Rotor Systems Using Holzer and Matlab GUI Techniques

A modified approach for the analysis of torsional vibrations in some rotor systems using modified Holzer and Matlab techniques, by building a graphical user interface (GUI), has been developed. The specific objective of this work is to illustrate the applicability and usefulness of the modified approach and the Matlab GUI in analyzing the effects of torsional vibration on some well known rotor systems such as two, three, and five rotor systems. Well Known problems in the field of torsional vibration were analyze. The results illustrate that the developed approach and the GUI are very useful tools for engineers, designers, and analysts of vibration problems in rotor systems.

Vibration Analysis of a Single‐Cylinder Reciprocating Compressor considering the Coupling Effects of Torsional Vibration

A piston slap is one of the main vibration sources of the reciprocating machinery. Much work has been done in this field, most of which was based on a constant rotating speed. However, in practice, the speed of a crankshaft may always fluctuate due to the uneven load or excitation. The inertia forces of moving components are much different at the fluctuating rotating speed comparing with that at a constant speed. In this paper, the piston slap and the induced vibration are analyzed based on the instantaneous angular speed measured on a single‐cylinder reciprocating compressor. Firstly, the dynamics of a crank‐connecting rod mechanism is analyzed based on the measured instantaneous angular speed which contains the torsional vibration of the air compressor. The time histories of piston slap impact forces considering and without considering torsional vibration are compared. Then, in order to correlate the piston slap impact with the slap‐induced vibration, the corresponding transfer functions between the middle stroke of the outer surface of the cylinder liner and the excitation points are measured. And the excitation force on the main bearing is also taken into account to bring the simulation closer to the experimental results. The effects of a torsional vibration on the vibration of the cylinder liner are analyzed, and the simulation results show that the torsional vibration is a factor that must be taken into account in the vibration analysis of the single‐cylinder reciprocating compressor.

The dynamics of eccentric block in a fully mechanical vertical drilling tool under the effect of torsional vibration

In present, the drilling industry have to face the reality of low oil and gas prices, fully mechanical vertical drilling tool is likely to become the best choice for vertical drilling in the future...

Vibration characteristics analysis of the new pin-cycloid speed reducer

A new pin-cycloid speed reducer with flexibility structure was designed and its nonlinear dynamic characteristics were analyzed. The eight-degree of multi-factor coupling dynamical models of traditional and the new pin-cycloid speed reducer were established by adopting theory of concentrated parameter, and vibration differential equations were built, respectively, on the basis of Newton’s second law. Then, these differential equations were solved and vibration features of pin-cycloid speed reducer were obtained. The results indicate that vertical and torsional vibration effects of cycloid gear and low-speed shaft are reduced after adopting flexibility mats. Moreover, vibration test was carried out, and experimental results are in good agreement with theoretical analysis results. The new pin-cycloid speed reducer’s vibration effect is superior to the traditional one.

The Effect of Torsional Vibrations on Metal Cutting Dynamics

The effect of torsional vibrations on the dynamics of metal cutting processes is studied. An extended dynamic process model is presented, where the spindle angle and the time delay are dynamic variables resulting in delay differential equations with state-dependent delay. Stability lobes are calculated based on the new extended process model and compared with results from the classical chatter theory with constant spindle speed and delay. For an ideal symmetric tool, stable cutting is characterized by a periodic spindle speed but still a constant delay. In this case, the main difference between the new extended and the classical model is a different periodic solution to periodic torsional tool displacements, which results only in slight modifications of the stability lobes. However, the new theory shows that it is important to consider tool asymmetries (e.g. runout), because this would result in periodically varying delays during stable cutting and larger stability changes due to torsional vibrations.

Effects of torsional vibration of a propulsion shafting system using a large-scale two stroke marine engine with a waste heat recovery system

Effects of torsional vibration of a propulsion shafting system using a large-scale two stroke marine engine with a waste heat recovery system

Planetary Gearbox Torsional Vibration Effects on Wound-Rotor Induction Generator Electrical Signatures

In this paper, torsional vibration effects of a planetary gearbox on electrical signatures of a wound-rotor induction generator have been studied in a representative complex electromechanical system through both numerical simulations and experiments. A universal lumped-parameter model has been developed with consideration of impacts of main drive-train mechanical components. This model has been adapted to a reduced-scale wind turbine simulator based on a 5.5-kW three-phase wound-rotor induction generator used for experimental validation at different load conditions. For this system, it has been demonstrated that most of mechanical characteristic frequencies of the planetary gearbox are difficult to be identified in the stator current spectrum. Nevertheless, the proposed approach has been used as an initial stage to assess the effectiveness of noninvasive condition monitoring of a planetary gearbox based on electrical signatures analysis.

Development and experimental performance validation of torsional viscosity damper for crank shaft system of transporting machine

The purpose of the present study is to deal with the development of a viscosity damper for the crank shaft system of a transporting machine using reverse engineering. A viscosity damper is developed to substitute import product. An engine simulator for performance evaluation has been produced to enable the control of engine speed using a PID controller and to evaluate the performance of several models by reverse engineering. Several prototypes are made according to the mass variation of an inertia ring. To evaluate the reduction effect of torsional vibration by viscosity damper, several sensors are used such as microphone, tri-axis accelerometer and the optical fibre sensor. In addition, order tracking and FFT (Fast Fourier Transform) analysis are performed by FFT analyzer and F/V converter according to speed increase (1,000~4,000 rpm). The viscosity damper for a high performance to reduce torsional vibration has been developed successfully using several designs, structural stability analysis and manufacturing techniques, as well as performance tests.

Graphical User Interface (GUI) for Torsional Vibration Analysis of Rotor Systems Using Holzer and MatLab Techniques

In this study, a new approach for the torsional vibration analysis of rotor systems using Holzer and Matlab techniques, by developing a graphical user interface (GUI), has been introduced. The objective of the work is to show the usefulness and power of Matlab GUI in investigating and analyzing the effects of torsional vibration on rotor systems. Also to carry out an analysis using the developed GUI to simulate three different rotor configurations such as 2-Rotor, 3-Rotor, and 5-Rotor systems. Illustrated problems in the field of analysis of torsional vibration are carried out. The results show that the developed GUI is very useful for engineers, designers, and analysts of torsional vibration problems in rotor systems.

Multivariate statistical analysis strategy for multiple misfire detection in internal combustion engines

This paper proposes a multivariate statistical analysis approach to processing the instantaneous engine speed signal for the purpose of locating multiple misfire events in internal combustion engines. The state of each cylinder is described with a characteristic vector extracted from the instantaneous engine speed signal following a three-step procedure. These characteristic vectors are considered as the values of various procedure parameters of an engine cycle. Therefore, determination of occurrence of misfire events and identification of misfiring cylinders can be accomplished by a principal component analysis (PCA) based pattern recognition methodology. The proposed algorithm can be implemented easily in practice because the threshold can be defined adaptively without the information of operating conditions. Besides, the effect of torsional vibration on the engine speed waveform is interpreted as the presence of super powerful cylinder, which is also isolated by the algorithm. The misfiring cylinder and the super powerful cylinder are often adjacent in the firing sequence, thus missing detections and false alarms can be avoided effectively by checking the relationship between the cylinders.

Torsional Vibration Effects on Induction Machine Current and Torque Signatures in Gearbox-Based Electromechanical System

The monitoring of heavy-duty electromechanical systems is crucial for their preventive maintenance planning. In these systems, the mechanical anomalies such as load troubles, great torque dynamic variations, and torsional oscillations lead to shaft fatigue and aging of other mechanical parts such as bearings and gearboxes. In this paper, a gearbox-based electromechanical system is investigated. Initially, a simple gearbox dynamic model is used to show the effects of rotating input, output, and mesh frequency components on the electromagnetic torque and consequently on the stator current signature. By this model, the influence of transmission error, eccentricities of pinion/wheel, and teeth contact stiffness variation is demonstrated for a healthy gearbox. Then, it is shown that the electrical machine can be considered as a torque sensor through electromagnetic torque estimation for torsional vibration monitoring without any extra mechanical sensor. A test-rig based on a 5.5-kW three-phase squirrel-cage induction motor connected to a wound-rotor 4-kW induction generator via a one-stage gearbox has been used to validate the proposed method.

Development of a Torsional Behavior Powertrain Model for Multiple Misfire Detection

Many methodologies have been developed in the past for misfire detection purposes based on the analysis of the instantaneous engine speed. The missing combustion is usually detected, thanks to the sudden engine speed decrease that takes place after a misfire event. Misfire detection and, in particular, cylinder isolation are nevertheless still a challenging issue for engines with a high number of cylinders, for engine operating conditions at low load or high engine speed, and for multiple misfire events. When a misfire event takes place, a torsional vibration is excited and shows up in the instantaneous engine speed wave form. If a multiple misfire occurs, this torsional vibration is excited more than once in a very short time interval. The interaction between these successive vibrations can generate false alarms or misdetection, and an increased complexity when dealing with cylinder isolation. This paper presents the development of a powertrain torsional behavior model in order to identify the effects of a misfire event on the instantaneous engine speed signal. The identified wave form has then been used to filter out the torsional vibration effects in order to enlighten the missing combustions even in the case of multiple misfire events. The model response is also used to speed up the setup process for the detection algorithm employed, thus evaluating, before running specific experimental tests on a test bench facility, the values for the threshold and the optimal setup of the procedure. The proposed algorithm is developed in this paper for an SI L4 engine; its application to other engine configurations is possible, as is also discussed in this paper.

Modeling and Simulation of Driveline Test Bench for Automotive Chassis Component System

Vibration in a driveline is presented in this paper. In the experiment, the rear subframe and propeller shafts and axle were composed and mounted with rubber each other. For applying the vibration input instead of the torsional vibration effect of an engine, the shaker was taken. In particular, torsional vibration due to fluctuating forced vibration excitation across the joint between driveline and rear subframe was carefully examined. Accordingly, the joint response was checked from experiments and the FE-simulation using FRF (frequency response function) analysis was performed. All test results were signal processed and validated against numerical simulations. In present study, the new test bench for measuring the vibration signal and simulating the vehicle chassis system was proposed. The modal value and the mode shape of components were analyzed using the model to identify the important components affecting driveline noise and vibration. It could be reached that the simplified test bench could be well established and be used for design guide and development of the vehicle chassis components.

Improved model of chatter in grinding, including torsional effects

To date the effect of torsional vibration on grinding chatter has been largely ignored. Recent research on cylindrical plunge grinding has shown, however, that the torsional characteristics can signi. cantly modify system behaviour and in certain circumstances may stop chatter from occurring. In order to investigate this in more detail, both frequency and time domain solutions have been developed for a cylindrical grinding model. A description of these solution methods and a comparison of their results are presented in this paper. The potential for tailoring the torsional characteristics of the system to improve or eliminate chatter in cylindrical grinding is con. rmed by both models.