Intermediate Shaft Research Articles

A Coupled Torsional-Transition Nonlinear Vibration and Dynamic Model of a Two-Stage Helical Gearbox Reducer for Electric Vehicles

A coupled torsional-transition nonlinear dynamic model of a two-stage helical gear (TSHG) reduction system for electric vehicles (EVs) is presented in this paper. The model consists of 16 degrees of freedom (DOF), which includes factors such as the nonlinearity of backlash, time-varying mesh stiffness (TVMS), mesh damping, supporting bearings, static transmission error (STE), and the torsional damping and stiffness of the intermediate shaft, in which the fourth-order Runge–Kutta numerical integration method was applied to solve the differential equations. With the help of bifurcation diagrams, time-domain histories diagrams, amplitude-frequency spectrums, phase plane diagrams, Poincaré maps, root-mean-square (RMS) curves, peak-peak values (PPVs), and Lyapunov exponents, the effects of pinion rotational speed, backlash, torsional stiffness, and torque fluctuation on the dynamic behavior of TSHG system are investigated. The stability properties of steady-state responses are investigated using Lyapunov exponents. The results reveal various types of dynamic evolution mechanisms and nonlinear phenomena such as periodic-one responses, quasiperiodic responses, jumps phenomena, and chaotic responses. The research presents useful results and information to vibration control and dynamic design of the TSHG transmission system used in EVs.

Torsional Vibration Stress and Fatigue Strength Analysis of Marine Propulsion Shafting System Based on Engine Operation Patterns

Modern merchant ships use marine propulsion systems equipped with an ultra-long-stroke diesel engine that directly drives a large slow-turning propeller. Such systems use fewer cylinders and generate greater power at slower shaft speeds, which affords improved propulsion performance as well as low repair and maintenance costs. However, this also results in higher torsional vibrations, which can lead to the fatigue of the shafting system. Tests performed on various marine propulsion systems with 5- to 7-cylinder engines have shown that engines with fewer cylinders exhibit a correspondingly wider barred speed range (BSR) and higher torsional vibration stresses. Thus, it is necessary to investigate the optimal engine operation patterns required to quickly pass the BSR with smaller torsional vibration. In this study, we carried out a series of BSR passage experiments during actual sea trials to evaluate the intermediate shaft performance under different engine operation patterns. The fractional damage accumulations due to transient torsional vibration stresses were calculated to estimate the fatigue lifetime of the shafting system. Our analysis results show that the torsional fatigue damage during BSR decelerations are small and negligible; however, the fractional damage during accelerations is a matter of concern. Our study determines the optimal main engine operation pattern for quick passage through the BSR with the smallest torsional vibration amplitudes and the least fractional damage accumulation, which can therefore extend the fatigue lifetime of the entire propulsion shafting system. Based on this analysis, we also suggest the optimum engine pattern for safe BSR passage.

Analysis of the Position of the Reducer Intermediate Shaft’s Influence on Bearing Selection

The proper configuration of the bearing not only affects the internal structure and service life of the gearbox, but also determines the service life of the bearing itself. In this paper, through changing the angle formed by the input shaft and the intermediate shaft of two-stage reducer in the transverse position, the model was built for several times. the changes of bearing force, bearing damage degree and fatigue life under different conditions were compared and analyzed, and the optimal type of the intermediate bearing was selected according to the results.

Frequency Based Damage Detection and Localization of Propeller Shaft of a Ship Using Experimental Modal Analysis

: The whole ship is dependent on the propeller shaft for its movement, the vibrations produced from the shaft destabilizes the whole ship and may lead to accidents. With this objective in mind, in this paper, we describe a methodology to detect and locate the crack present in the intermediate simply supported shaft using experimental modal analysis. In the present work, 304 stainless steel material shaft is taken as the specimen as it is one of the most versatile and widely used steels in the world for making different shafts used in any machinery equipment like ships propeller shaft, engine shafts, motor shafts. Initially, analytical analysis is done on the simply supported shaft then numerical modal analysis using ANSYS 2019 R3 software. Results obtained from the numerical modal analysis are compared with the experimental modal analysis which is done using FFT analyzer. Finally, the first three natural frequencies are used as a tool to detect damage detection and location in the propeller intermediate shaft

동일 주파수 성분의 디젤엔진과 프로펠러 기진력 위상차 규명을 이용한 선박 진동 제어

A two-stroke diesel engine and a propeller normally adopted in large merchant ships are regarded as major ship vibration sources. They are directly connected and generate various excitation components proportional to the rotating speed of diesel engine. Among the components, the magnitude of two excitation components with the same frequency generated by both engine and propeller can be compensated by the adjustment of their phase difference. It can be done by the optimization of propeller assembly angle but requires a number of burdensome trials to find the optimal angle. In this paper, the efficient estimation method to determine optimal propeller assembly angle is proposed. Its application requires the axial vibration measurement in sea trial and the numerical vibration analysis for propulsion shafting which can be substituted by additional vibration measurement after one-trial modification of propeller assembly angle. In order to verify the validity of the proposed method, the phase difference between two fifth order excitation components generated by both diesel engine and propeller of a real ship is calculated by the finite element analysis and its result is indirectly validated by the comparison of axial vibration responses at intermediate shaft obtained by the numerical analysis and the measurement in sea trial. Finally, it is numerically confirmed that axial vibration response at intermediate shaft at a resonant speed can be decreased more than 87 % if the optimal propeller assembly angle determined by the proposed method is applied.

Self-Excited Torsional Vibration in the Flexible Coupling of a Marine Propulsion Shafting System Employing Cardan Shafts

The reliability of propulsion shafting systems is a major concern for ocean-going vessels because mid-ocean repairs can be time-consuming and spare parts must be available. To address this concern, vibration modeling and experimental measurements were conducted on a propulsion shafting system with a Z-drive propeller, with the objective of identifying the source of failure for the flexible rubber coupling connecting the diesel engine with the intermediate shaft. The torsional fluctuations in the flexible coupling dramatically increased and then abruptly ceased. The modeling results revealed that the frictional losses during power transmission through the universal joints could act as an excitation force for self-excited vibration. The coupling connected to the intermediate shaft did not have sufficient radial flexibility to dampen these vibrations. To avoid the effects of the self-excited torsional vibration, it is recommended that this coupling is replaced with one that is capable of absorbing the radial shaft displacement.

Failure analysis of tapered roller bearing inner rings used in heavy truck

Hoop brittle fracture took place on several tapered roller bearing inner rings during assembling with the intermediate shaft. All the cracking took place on the laser marking area on the small head end of inner ring representative of product identification. Detailed metallurgical analysis revealed that two kinds of metallurgical defects mainly occurred on the small head end of cracked inner rings: (1) several of deep and narrow near-surface micro-grooves resulting from laser marking were distributed dispersively on the small head end of inner ring, (2) the thermal softening resulting from grinding burn occurred on the small head end of inner ring, causing decrease in surface hardness as well as development of tensile stress. The crack origins were all located on the overlapping zone of the laser marking area and grinding burn area. Cracks initiated from the micro-grooves and propagated toward the inner along the axial under the action of assembly stress. The presence of the near-surface micro-grooves as sharp notches on the laser-marked small head end was mainly responsible for the fracture failure of inner rings. The occurrence of the thermal softening layer due to grinding burn on the small end of inner ring, consequently leading to decreasing in the surface hardness and resultant low tensile strength, promoted the crack initiation and propagation.

Design of A Dual-rotor Engine Driving by the Elliptic Gear

Aiming at the shortcomings of the crank-connecting rod mechanism engine, such as low transmission efficiency and high side pressure between the piston and the cylinder, the paper proposes a kind of dual-rotor engine driving by the elliptic gear. The left and right rotors are driven by the gas pressure in the cylinder, and then the elliptic gears on the output shaft are driven by the circular gears and the elliptic gears on the intermediate shaft. When the gears rotate, the output shaft connected outputs power again and again. The rotor rotates one circle, the four “cylinders” separated by the rotor work one time respectively, and the output shaft rotates two circles. The results of the calculation and the simulation test show that the serialization design can be carried out by setting different parameters of the long half-axis and the eccentricity. When the value of the long half-axis (100mm in this design) is fixed and the eccentricity is 0.4, 0.6 or 0.8, the rotation angle and the speed of the left and right rotors change obviously. The greater the eccentricity, the greater the difference of the rotation angle and the speed of the left and right rotors. The higher the compression ratio of engine, the higher the transmission efficiency.

Weight efficiency analysis of a ship carbon shaft manufactured by winding with various winding angles in layers

The task of the optimal winding parameters selection for the ship composite intermediate shaft has been formulated and the solution algorithm has been considered. A method for the shaft mechanical characteristics estimation on the base of the layer-by-layer method has been proposed. The shaft weight efficiency analysis for the various winding angles in the winding program has been carried out.

Pulse gas-assisted multi-needle electrospinning of nanofibers

Multi-needle electrospinning is an effective method to increase the productivity of nanofibers. In this paper, the number of single-needle jets was increased to further improve the production efficiency. As the traditional method for increasing the number of single-needle jets has poor controllability and persistence, we proposed a gas-assisted method to increase the yield of nanofibers. A coaxial gas auxiliary needle was designed with an intermediate shaft supplied gas and the outer shaft supplied solution. Innovatively using pulse gas to produce continuous and stable bubbles which are ruptured on the needle. The liquid film is continuously disturbed, which generates jets in the electric field, thereby increasing the number of jets of a single needle. After optimization of the single-needle gas-assisted electrospinning process, the stable spraying process of 16-pin multi-needle electrospinning has been realized. The gas-assisted electrospinning productivity was 4.7 times higher than that of without gas assistance. It provided a new idea for improving the stable production of the multi-needle electrospinning.

프로펠러 가진에 의한 저속 디젤엔진을 갖는 추진축계의 종진동

The axial vibration of propeller-induced excitation can be mostly seen in warships that have high-speed rotation propulsion shafting systems equipped with reduction gears. Coupled torsional and axial vibration is mainly focused on the excitation force that is induced by the cylinder’s gas pressure and the piston’s reciprocating mass in low-speed two-stroke diesel engines with seven or fewer cylinders; more complex vibration modes with one or more nodes can be seen in engines with eight or more cylinders. This thrust variation force caused by the axial vibration is the excitation force of the ship’s deckhouse in the longitudinal direction and has been researched extensively in the past. Recently, super-size containerships have been built that have more than 20 000 TEU. These ships have adopted low-speed diesel engines with 10 or more cylinders as their prime mover and the distance between the propeller and the main engine has increased significantly due to the streamlining of their hulls. As a result, there is the probability of resonance between the propeller’s axial excitation and the second node vibration. While this vibration frequency is rare, the possibility of resonance with the ship’s superstructure can create vibrations in the pipes and various accessories surrounding the main engine and stern tube. In addition, severe vibrations can occur if the natural frequency of these parts and that of the axial vibration are similar, which necessitates installing an additional damper on the intermediate shaft that resembles an axial vibration damper that is attached to the crankshaft free end. This paper intends to research the characteristics of axial vibration through theoretical analysis and measurement data with a focus on the 2nd order axial excitation of the propeller blade number in a propulsion shafting system with a 11G90ME engine as the research model.

Sub case origin fatigue in teeth of helical gear of a TA 67n turbo reducer

The main aim of this study is investigating the possible failures classified as subcase origin fatigue and further case crushing. Because of these failure mechanisms, the teeth of the intermediate gears shaft may fracture after several cycles of operation of the whole gearbox. Shafts are used to machines which need to transmit rotary motion into a system of parts, such as roller bearings, gears, and pulleys. In this work, a helical gear manufactured with DIN 18CrNiMo7-6 steel is an integral part of a turbo reducer, had several teeth fractured after three months of operation. The teeth were heat treated as follow: carburizing, quenching, tempering following by grinding with grinding wheels resulting in a surface hardness of the teeth between 58 and 62 HRC. The analysis of failure surface shown a bright area between the lath martensite, which is retined austenite, that decreases the contact fatigue strength. The plastic deformation transforms the retained austenite to untempered martensite, promoting the weakening of the hardened layer. The performance of composition analysis, macromolecular, optical microscopy, microhardness, and scanning electron microscopy, makes possible identifying that the crack nucleates close to the pitting corrosion line between the flank and the working face of the gear tooth. Cracks nucleated preferentially in the sublayer and propagated because of the contact fatigue, usually, pull out the upper part of the tooth entirely, which results in static propagation by the case crushing mechanism.

Crack Progression from Inside to Outside of Intermediate Shaft Flange Mating Surface

Crack Progression from Inside to Outside of Intermediate Shaft Flange Mating Surface

Design and analysis of the propulsion shafting system in a ship with single stern tube bearing

In recently constructed vessels, minimization of engine room volume is required to maximize the volume of cargo to be shipped. Therefore, the main engine and the stern bulkhead mounted on the ship are installed as far as possible in the aftward direction. As a result, the length of the propeller shaft is reduced, along with the stern tube bearing span used to support it. In this case, the shaft flexibility is reduced, the reaction influence number is increased, and the point load of each bearing is easily influenced by change in displacement. Because the point load of each bearing is susceptible to hull deformation and thermal expansion, it is difficult to adjust the shaft arrangement and the bearing load change after large adjustment of the shaft arrangement. Therefore, in the past, the bearing was arranged to support the propeller shaft with two forward and afterward stern tube bearings. However, when the main engine and the stern bulkhead are installed as far aftward as possible to minimize the volume of the engine room, it is necessary to provide shaft flexibility by removing the forward stern tube bearing. As a result, the resonance revolution of the propeller blades during whirling vibration of the propulsion shafting system falls within the range of normal operating revolutions. This means that abnormal wear of the stern tube bearing, damage to the stern tube sealing device, and hull structure vibration may occur due to the whirling vibration. In this paper, the characteristics of shafting alignment and whirling vibration of a ship supporting a propeller shaft with double and single stern tube bearings are compared. Moreover, the changes in shaft flexibility and the characteristics of the whirling vibration of a corresponding shafting system in a 50 K-DWT petroleum product tanker were explored by applying a single stern tube bearing. In addition, the shafting alignment and whirling vibration are determined according to the installation position of the intermediate shaft bearing. A method is suggested for selecting the optimal shafting arrangement by which to secure the shaft flexibility of a ship to which a single stern tube bearing is applied, and to avoid resonance from the whirling vibration.

Vibration characteristics of filament wound composite tubes applied to the intermediate shaft in ship propulsion system

In this study, the CFRP shafts made up of T700-SC multilayered composites have been designed to replace the steel shaft of a ship. An important design variable to be considered when designing composite material intermediate shafts is the natural frequency for resonance avoidance at critical rotational speed and torsional strength for axial load. In order to satisfy these, strength and modal analysis were performed. In order to minimize the deformation of the shape due to the residual stress after mandrel removal, it was laminated by axial symmetry. The fibers orientation angle has a great influence on the natural frequency of the drive shaft. The carbon fiber should be closely oriented at [Formula: see text] to improve the modulus of elasticity in the direction of length of the intermediate shaft and to increase the natural frequency. Also, the optimum fiber orientation for maximum torsional strength should be close to [Formula: see text]. The stacking pattern and the stacking order were finally decided considering the results of the finite element analysis (FEA).

Optimization winding design of a composites intermediate shaft

The purpose of this study is to determine the correct estimation of the laminate patterns for composites intermediate shaft. The laminate patterns in the filament winding process are an important factor in determining the strength and life of the final structure. In this study, the structural safety was analyzed for the laminate patterns in four cases. In addition, this work evaluated the range of laminated angles for optimal thickness selection. The laminate patterns and the order of the layers were determined by considering the results of the finite element analysis. The shear stress equation of the hollow shaft for torsional loads showed that the thickness of the structure varied with the diameter ratio. At the maximum diameter ratio (the smallest shaft thickness), the required shear strength for the structure was 36.6 MPa. Also, the most stable stress distribution was selected at [Formula: see text] to [Formula: see text]. The shear modulus according to the laminated angle was considered to give the best strength value when stacked at [Formula: see text]. The research results in this study suggest that the design of an optimized intermediate shaft of composite materials can be supplemented.

Validation of analytical methods for the estimation of the torsional vibrations of ship power transmission systems

The propulsion system is one of the main sources of ship vibrations. A typical propulsion system consists of an engine, a shaft line and a propeller. In order to estimate the vibration levels of a ship propulsion system, analytical methods are still relevant in the preliminary ship design stage. In this paper, three analytical procedures for the vibration analysis of a ship shafting system are presented. The shafting system dynamic behaviour is simulated by reducing the problem to two-, three-, and multi-mass models. Propeller and engine damping is taken into account. Differential equations of motion for the two- and the three-mass models are solved analytically. In the case of the multi-mass model, Rayleigh's quotient and the Galerkin method are used for free and forced vibration analysis, respectively. Since the first natural mode of the shaft line is dominant, the problem can be reduced to a single d.o.f. in the modal space and solved analytically. For all three models, relatively simple formulae for the engine torque transfer factor to the intermediate shaft are derived. The presented procedures are validated by a comparison with measurements. The comparison indicates the high accuracy of the proposed procedures.

Study of the Hardening in Middle Shaft During Cold Forging

Cold forging is a common processing method. It is fast, precise, and produces high strength. The purpose of this study was to process products by using a cold-forging technique. This study is aimed at achieving hardness of a certain standard without using heat treatment; computer-aided engineering (CAE) analyses were conducted with different diameter settings but the same methods and molds. Tests were conducted to understand the influence of the changes in material diameters on their material hardness values. We expected to produce workpieces of a specific hardness at the lowest cost. An actual cold forging case was conducted. First, Deform-3D (finite element analysis software) was utilized to conduct a computer-aided engineering forging analysis. How the internal stress distribution and equipment output tonnage changed as the diameter of the material changed was observed and compared against the actual hardness. This study discovered that the location where large elastic deformation occurred (i.e., where the stress concentration occurred), the hardness of the cold forging piece at that location increased. The simulation and experiment results revealed that a large area reduction rate of the intermediate shaft formation resulted in dense forging streamlines, high hardness, and substantial hardening effects.

Vertical flow constructed wetlands for decentralized wastewater treatment in Jordan: Optimization of total nitrogen removal

The baseline performance of two full-scale vertical flow (VF) constructed wetlands operating in the arid climate of Jordan is presented in this study, within the context of the Jordanian Standards for reuse of treated wastewater. One system was a recirculating VF wetland, and the other was a single-pass two-stage VF wetland. Operational modifications were made to each treatment system, with the aim of improving Total Nitrogen (TN) removal. For the recirculating VF system, attached-growth media was added to the recirculation tank to provide increased surface area for growth of denitrifying bacteria. The modification showed a small but significant improvement in TN removal (8 mg/L less than the baseline phase; p = 0.004). Statistical analysis showed that 30% and 4.5% of the increase in compliance with the TN limits (Class A and Class B/C, respectively) could be attributed to the modification. The two-stage VF wetland was modified with a step-feeding line that introduced carbon-rich raw wastewater to the intermediate pump shaft just upstream of the second-stage filter. The modification also resulted in a small but significant improvement in TN removal (13 mg/L less than the baseline phase; p = 0.005). The increase in compliance with the TN standard due to the modification was estimated at 20% and 22% for Class A and B/C, respectively. The simple operational modifications proved to be effective for improving total nitrogen removal in arid climate VF wetland systems.

Z-드라이브 프로펠러용 탄성커플링의 설계와 동특성

Propulsion shafting system applying diesel engine with reduction gear as prime mover generally installs an elastic coupling between the engine and the intermediate shaft. This coupling normally isolates the vibratory torque excited by diesel engine or the excess transient torque and moment occurring due to external impact. Hence elastic coupling allows the diesel engine and reduction gear to operate safely. In this paper, repeated breakdown of the elastic coupling occurred on a skimmer vessel propulsion shafting due to unknown vibration during sea trial. The authors investigated the probabilities and causes of the elastic coupling failure thru global vibration measurement and past incident analysis.