Crankshaft Systems Research Articles

Analysis of rigid-flexible coupled torsional vibration and vibration suppression of crankshaft system under multiple working conditions

With the rapid development of shale gas resources in China, there is an increasing demand for large and multiple column compressors. However, this development has brought to light the issue of torsional vibration in compressor crankshaft systems, particularly under variable loads and multiple working conditions. In order to reduce the torsional vibration of the compressor crankshaft and ensure the safe and stable operation of the compressor unit, this study proposes a method for calculating and suppressing torsional vibration in the crankshaft system of a shale gas compressor, which takes into account the flexibility effect of various parts and considers multiple working conditions. The analysis focused on the rigid-flexible coupling torsional vibration characteristics of the crankshaft system under multiple working conditions, considering the flexible deformation of the main bearing, connecting rod, and crankshaft. The study successfully determined the torsional vibration response of the crankshaft system under seven typical working conditions. Furthermore, for the worst conditions, a detailed analysis of the vibration response of the crankshaft system was conducted and carried out a study on suppressing crankshaft torsional vibration through response surface optimization design. The study findings indicate that the compressor system exhibits low-frequency vibrations during operation. The maximum torsional angular deformation at the crank pin of the fourth column is measured to be 0.052°. Following structural optimization, the relative torsional angular deformation of the crank pin is reduced by 25.61% under the worst operating conditions. Moreover, the peak angular velocity of the center of mass is reduced by 22.17%. These results demonstrate a significant suppression effect on torsional vibrations in the compressor crankshaft system, leading to improved working safety.

The Effect of Multi-Walled Carbon Nanotubes Additives on the Tribological Properties of Austempered AISI 4340 Steel

Due to a combination of optimal properties such as great strength, high hardness, good process ability, and good mechanical properties, AISI 4340 steel is widely used in many critical industrial applications such as nuclear, military, defense, and aerospace. It is also widely used in hydraulic forged machine tools, forged automotive crankshaft systems, shafts and gears, because of their improved characteristics, and its good tribological properties. The purpose regarding this work is to check the tribological characteristics of austempered AISI 4340 steel while dry and lubricated with machinery oil of SAE 30 grade as base oil. As received, AISI 4340 steel samples have been austempered to four definitely austenitic phase temperatures (850℃, 900℃, 1000℃, and 1050℃) for 90 minutes before being immersed in a mixture of potassium nitrite and sodium nitrite at 400℃ for 45 minutes. Friction and wear tests were then performed on austempered samples. Multi-walled carbon nanotube particles were blended at weight concentrations of 0.055, 0.1, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, and 0.45 with typical machinery oil of 30 grade as base lubricant oil. A pin on the disc wear configuration was used in the experimental investigation. The use of Multi-Walled Carbon Nanotube (MWCNTs) additives in the base oil resulted in a decrease in both friction coefficients and wear rates values when compared to typical base oil lubricant. The results also showed a reduction in both friction coefficients and wear rates as the sample's austempering temperatures were raised. Sliding surfaces were also photo micro graphed, and when the volume concentrations of Multi-Walled Carbon Nanotube particles in the normal base oil lubricant were increased, smoother surfaces with less damage were shown.

Nonlinear energy transfer from an engine crankshaft to an essentially nonlinear attachment

This study proposes an application of lightweight vibration control strategy known as nonlinear energy sink (NES) to mitigate the undesired vibrations in engine crankshaft systems. Linear vibration absorbers have long been used to suppress undesired vibrations. These devices can be tuned to reduce vibrations at a single frequency while adding extra inertia to the powertrain system. On the contrary, the NES is a lightweight vibration energy absorber. The presence of essential nonlinearity in the NES design provides the means for realization of irreversible targeted energy transfer (TET) from the primary system to the NES and attenuation of energy over a wide range of frequencies. This study introduces the conditions critical to achieve TET through its mathematical analysis and understanding the dynamical mechanisms governing this phenomenon in a strongly nonlinear transient dynamical system.

Identification of a model of the crankshaft with a damper of torsional vibrations

The paper presents modelling and the process of dynamic model identification of the crankshaft system. At the beginning some information about design, operation and test of crankshaft systems is shown. The next section describes the process of the crank-piston mechanism with a vibration damper modelling and the method of obtaining the motion equation. The last but one section demonstrates some aspects of the process of dynamic model identification. Moreover, tests and numerical simulation are presented. At the end, there is a summary of the whole paper. Conclusions about modelling and identification of the dynamic model of crankshaft systems are shown.

Analysis of bending and angular vibration of the crankshaft with a torsional vibrations damper

The paper presents the analysis of vibrations of the crankshaft system and proposition of its modelling. At the beginning there are general information about the torsional vibration dampers. Moreover, models of different kinds of dampers are shown with their governing equations. The next section presents proposition of the algorithm of modelling of the crank-piston mechanism with a torsional vibrations damper. Furthermore, there are equations of motion of the analyzed system in this chapter. After that, the results of numerical simulations and experiments are shown. Finally, the paper is summarized by giving conclusions about the analysis of crankshaft systems with a dynamic eliminator of vibrations and their modelling.

Dynamic Simulation of a Crankshaft

Crankshafts are one of the most important parts of a reciprocating engine. A°t basically connects driveline system to the pistons which gives the motion. Main aim of Crankshaft systems designs are to have lower bearing forces, lower torsional vibrations and higher fatigue strength. But, due to complexity of the geometry, lack of manufacturing quality and nonlinear forces, it is hard to analyze the characteristics of the crankshaft. In this paper, a 2D representation of a crankshaft model was built with load information from connecting rods and other specifications. The resultant bearing forces and harmonics of the crankshafts were calculated with given data. The AVL Excite software program was used to simulate the crankshaft of an engine.

Multi-mode and rubber-damped Torsional Vibration Absorbers for engine crankshaft systems

With the development of lightweight design and the high power output of an engine, the effectiveness of Torsional Vibration (TV) control for an engine crankshaft with an ordinary Single Mode and rubber-damped TV Absorber (SMTVA) is limited. In this paper, the configurations of some Multi-Mode and rubber-damped TVAs (MMTVA) having more than one inertial mass are introduced firstly, then a detailed procedure for modelling a TV system for a generic crankshaft system is presented. Thirdly, an optimisation method for determining the design parameters of a MMTVA (mass ratios, frequency ratios and damping ratios) is developed. The proposed calculation method is based on reducing the TV of a crankshaft. The calculated results show that MMTVA can reduce crankshaft TV greatly although the damping of each SMTVA in a MMTVA is provided with the rubber materials.

Effect of Damping on Parametrically Excited Torsional Vibrations of Reciprocating Engines Including Gas Forces

In recent years, several cases of secondary resonance have been found in torsional vibrations of crankshaft systems. In some reciprocating large marine diesel engine systems, these effects have been a contributing factor of catastrophic failures. In these instances, design based on invariable inertia characteristics of the systems and using constant damping could not project the existence of adverse situations that led to excessively large motions. Most of the mathematical models considered thus far either give limited information on the effects of damping or restrict the analysis to an undamped variable inertia system with gas forces to avoid complexities. As a result, these models do not highlight all the consequences of such motion. This paper presents the equation of motion with key nondimensional parameters to include both damping and external excitations in order to predict the complete response of an equivalent single-cylinder engine system. Additionally, the nondimensional mathematical model presented in this paper allows development of design charts and brings the analysis closer to becoming an effective design tool. This model extends the previous analytical model by the author (2001) to include the effects of damping and gas forces acting on the system and captures many of the important concepts of time-dependent inertia systems. The complex waveform responses are examined within the range of engine speeds at which inexplicable crankshaft failures are known to have occurred. The investigations are conducted to study the interaction of secondary resonance effects with harmonic excitations for variation in damping and inertia ratios. These studies show that the observed effect is a natural physical phenomenon arising from the variable inertia characteristics of the system, and under certain circumstances it can have a serious impact on torsional vibration. The conclusions reached in this paper differ from those of Draminsky (1961) and Hesterman and Stone (1994). Comments on these differences are also included.

Modelling and experimental study on bending vibration of a diesel engine crankshaft

In recent years, a considerable amount of research effort has gone into the investigation of free and/or forced vibration characteristics of a spinning shaft with attached discs, but there has been less research on the transverse vibration of a high-speed diesel engine crankshaft system under firing conditions. This paper presents a new exact general approach based on a distributed continuous model to study the free and forced bending vibrations of an engine crankshaft. Distributed continuous models of the crankshafts for a four-cylinder (with a capacity of 3.8 l) and an in-line six-cylinder (with a capacity of 5.8 l) direct-injection diesel engine were constructed. The general frequency equation and mode shapes for the bending vibration of the total crankshaft under operating conditions were obtained using the coefficients transfer matrix method. Modelling and analysis procedures were applied to the crankshaft systems of two diesel engines, and the inherent frequencies of the crankshaft within overall engine speeds were calculated. Then, equations to simulate the steady state vibration amplitudes when the gas forces, rotating masses and reciprocating masses exerted at the crankshaft were deduced. The bending amplitudes at the front free end of the crankshaft were calculated using this method. To verify the modelling and the results of the calculations, the bending vibrations were measured at the front end of the crankshaft using a newly designed device. It is found that there was good agreement between the analytical results and the experimental results.

Development of simulation technology for dynamic behavior of crankshaft systems in motorcycle engines

In order to improve durability and marketability of an engine and reduce the development period, a crankshaft system simulation technology was developed. A crankshaft and a crankcase are modeled using the finite element method (FEM). The models and a calculation model of the hydrodynamic reaction force of bearings are linked and the crankshaft behavior is calculated using numerical integration within the time domain. Therefore, this simulation technology enabled accurate prediction of the motion behavior of a crankshaft up to the high operating speeds that are unique to motorcycle engines.

Aluminium bi‐metal bearing developments for automotive and medium speed diesel applications

Modern engines place increasing demands on crankshaft systems, and thus bearings are required to have properties which conflict with the simultaneous need for strength and compliance under all operational conditions. Lists property requirements to describe bearing behaviour. Covers strengthening mechanisms for aluminium alloys, conformability tests, compatibility, metallurgical consequences.

Dynamic stiffness matrix method for three-dimensional anaylsis of crankshaft vibrations. (2nd report. Application to solid structure crankshaft systems and the influence due to the oil film stiffness of crankshaft-journal bearing).

The modeling method and calculating process described in the earlier report were applied to two kinds of solid structure crankshaft systems: one for a three-cylinder in-line engine; the other for a V-six-type engine. Again, good agreement was obtained between the calculated results and the experimental ones. The influence of oil film stiffness of the crankshaft journal bearings on the vibration behavior of the crankshaft system was examined. The vibration behavior of the crankshaft system was predicted by taking account of the influences for a four-cylinder in-line engine, mentioned above, and the results were compared with experimental values.