scholarly journals A Fluid–Solid–Heat Coupling Analysis for Water-Lubricated Rubber Stern Bearing Considering the Deflection of Propeller Shaft

2021 ◽  
Vol 11 (3) ◽  
pp. 1170
Author(s):  
Yanfeng Han ◽  
Ting Tang ◽  
Guo Xiang ◽  
Hang Jia
Keyword(s):  
Load Condition ◽  
Water Film ◽  
Coupling Model ◽  
Euler Method ◽  
Integrated System ◽  
Asperity Contact ◽  
Propeller Shaft ◽  
Heavy Load ◽  
Rubber Bushing ◽  
Shaft Deflection

The novelty of the present study is that it investigates the effect of propeller shaft deflection, caused by the propeller self-weight and interfacial mixed forces, on the fluid–solid–heat (FSH) coupling performance of water lubricated rubber stern bearing (WLRSB). In the FSH coupling model, the generalized average Reynolds equation and the Kogut–Etsion asperity contact model are used to determine the hydrodynamic and the elastic–plastic contact behaviors of WLRSB. In the thermal analysis, the journal, water film, and rubber bushing are considered as an integrated system (JWR system) using the Euler method. To prove the correctness of the developed model, the predicted results are verified by comparisons with the experimental results given in the literature. In addition, to assess the effect of the force-driven deflection during FSH simulation, comparisons of the FSH predictions between the aligned journal case and the deflected journal case are carried out. The results indicate that, especially under a heavy load condition, the deflection of the stern shaft should be incorporated into the lubrication gap between the journal–rubber interface during the analysis of FSH performance of the JWR system.

Numerical study on the dynamic characteristics of water-lubricated rubber bearing under asperity contact

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guo Xiang ◽  
Yijia Wang ◽  
Cheng Wang ◽  
Zhongliang Lv
Keyword(s):  
Elastic Modulus ◽  
Contact Stiffness ◽  
Water Film ◽  
Radial Clearance ◽  
Asperity Contact ◽  
Stiffness Coefficient ◽  
Content Type ◽  
Damping Coefficients ◽  
Rubber Bearing ◽  
Stiffness And Damping

Purpose In this study, the dynamic characteristics of the water-lubricated rubber bearing considering asperity contact are numerically studied, including water-film stiffness and damping coefficients and plastic-elastic contact stiffness coefficient. Design/methodology/approach The Kogut-Etsion elastic-plastic contact model is applied to calculate the contact stiffness coefficient at the bearing-bush interface and the perturbed method is used to calculate the stiffness and damping coefficients of water-film. In addition, the rubber deformation is determined by the finite element method (FEM) during the simulation. Parametric studies are conducted to assess the effects of the radial clearance, rubber thickness and elastic modulus on the dynamic characteristic of water-lubricated rubber bearing. Findings Numerical results indicate that stiffness and damping coefficients of water film and the contact stiffness of asperity are increased with the decreasing of the radial clearance and the dynamic coefficients are less sensitive to the rubber thickness compared with the elastic modulus of rubber. Furthermore, due to the existed groove, a sudden change of the water film direct stiffness and damping coefficients is observed when the eccentricity ratio ranges from 0.6 to 1.0. Originality/value It is expected this study can provide more information to establish a dynamic equation of water-lubricated rubber bearings exposed to mixed lubrication conditions.

scholarly journals Dynamic Modelling and Analysis of the Microsegment Gear

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Yangshou Xiong ◽  
Kang Huang ◽  
Tao Wang ◽  
Qi Chen ◽  
Rui Xu
Keyword(s):  
High Speed ◽  
Load Capacity ◽  
Dynamic Performance ◽  
Dynamic Modelling ◽  
Weight Ratio ◽  
Load Condition ◽  
Main Idea ◽  
Heavy Load ◽  
Rotating Speed ◽  
Involute Gear

The development of technology requires higher load capacity, rotating speed, power-weight ratio, lower vibration, and noise with respect to the gear transmission. The new type microsegment gear’s tooth profile curve is composed of many microsegments. Previous researches indicate that the microsegment gear has a good static performance, while the dynamic behavior of the microsegment gear has never been investigated. This paper will focus on the dynamic performance of the gear. The profile deviation between microsegment gear and involute gear is regarded as a displacement excitation in the proposed dynamic model. The numerical analysis for three cases is conducted and the results shows that, in low-speed and heavy-load, medium-speed and medium-load conditions, microsegment gear and involute gear both exhibit a good performance, while, in high-speed and heavy-load condition, microsegment gear has a better performance than that of involute gear. The influence of backlash on the dynamic performance is also studied. It is found that the variation of backlash does not change the type of motion, but the vibration amplitude and the stability of the motion are much affected. The main idea in this paper is supposed to provide a novel method for the precision grinding of the microsegment gear.

Non-Linear Coupled Dynamics of a Flexible Propeller-Shaft System Supported by Water Film Bearings

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
Chang-Gang Lin ◽  
Ming-Song Zou ◽  
Can Sima ◽  
Li-Bo Qi ◽  
Yue Yu
Keyword(s):  
Nonlinear Vibration ◽  
Damping Ratio ◽  
Water Film ◽  
Vibration Characteristics ◽  
Superposition Method ◽  
Propeller Shaft ◽  
Chaotic Motions ◽  
Mode Superposition Method ◽  
Shaft System ◽  
Slice Method

Abstract A slice method to determine the boundary conditions between the stern bearing and shaft by dividing the journal in the stern bearing into several slice elements along the axial direction is proposed for the first time. A comprehensive finite element model considering the nonlinear force of the water film and the flexibility of the propeller blade is established for a propeller-shaft system. The long bearing approximation is adopted to calculate the pressure distribution around each journal element in the stern bearing. The mode superposition method is employed. The nonlinear equation of motion is solved iteratively using the Newmark method. A parametric study is implemented to analyze the nonlinear vibration characteristics of the system. It is shown that the real motion state of the journal in the stern bearing can be simulated more precisely by the slice method proposed. The responses of the system alternate among period-one, quasi-periodic, multi-periodic, and chaotic motions as the rotating speed increases. The damping ratio has a significant effect on the dynamic characteristics of the propeller-shaft system. The motion of the system is unstable when the damping ratio is very small. At this time, the modes of the flexible propeller blades can be excited readily. The slice method, which can also be extensively used in similar rotor-bearing systems in the engineering field, is very simple and efficient to analyze the nonlinear vibration characteristics of a flexible propeller-shaft system supported by water film bearings.

Study on Dynamic Characteristic of 64m Railway Steel Truss Bridge on Expanding Heavy-Load Transport Condition

2011 ◽  
Vol 90-93 ◽  
pp. 1100-1105
Author(s):  
Zhi Jie Sun ◽  
Jun Min Shen ◽  
Jian Bin Zhao ◽  
Zhong Ming Su
Keyword(s):  
Dynamic Performance ◽  
Load Condition ◽  
Vertical Acceleration ◽  
Performance Parameters ◽  
Heavy Load ◽  
Double Line ◽  
Truss Bridges ◽  
Conventional Condition ◽  
Steel Truss ◽  
Steel Truss Bridges

Through theoretical calculation, systemic analysis of dynamic performance of the 64m single and double line railway steel truss bridges on the expanding condition and conventional condition. Contrast and analysis the main dynamic performance parameters of bridges on the two kinds of operating condition. In 64m steel truss bridges of Shuozhou-Huanghuagang Railway application practice proves that on expanding heavy-load condition, the main dynamic performance parameters of bridges are slightly larger than conventional condition, but the variation law of vertical acceleration of mid-span is different.

The coupled effect of bearing misalignment and friction on vibration characteristics of a propulsion shafting system

2017 ◽  
Vol 233 (1) ◽  
pp. 150-163 ◽  
Author(s):  
Wenyuan Qin ◽  
Hui Qin ◽  
Hongbo Zheng ◽  
Zhiyi Zhang
Keyword(s):  
Torsional Vibration ◽  
Water Film ◽  
Vibration Characteristics ◽  
The Finite Element Method ◽  
Heavy Load ◽  
Runge Kutta Method ◽  
Coupled Effect ◽  
Rubber Bearing ◽  
Rubber Bearings ◽  
Mode Truncation

The propulsion shafting system of ships is usually supported, in part, by water-lubricated rubber bearings, which often work at mixed or boundary lubrication state under heavy-load and low-speed conditions, resulting in strong friction on the bearing–shaft interface and even abnormal vibration in the overall system. In addition, bearing misalignment can further affect the distribution of friction and consequently change the lateral and torsional vibration characteristics of the shafting system. In this work, the rubber bearing was simplified into parallel-distributed springs and the water film was neglected. The dynamic model of the propulsion shafting system was built with the finite element method and reduced by mode truncation. The coupled effect of bearing misalignment and friction was subsequently analyzed with this reduced model and the fourth-order Runge–Kutta method. Finally, lateral and torsional vibration characteristics of the overall system under different bearing misalignment were obtained, which can be used in the identification or diagnosis of abnormal vibration induced by friction.

Advanced Active Prestressed CFRP in RCC Structures

2015 ◽  
Vol 1129 ◽  
pp. 290-297
Author(s):  
Gopal L. Rai
Keyword(s):  
Reinforced Concrete ◽  
High Efficiency ◽  
Concrete Structures ◽  
Load Condition ◽  
Integrated System ◽  
Fatigue Properties ◽  
Reinforced Concrete Structures ◽  
Practical Applications ◽  
Cfrp Laminates ◽  
Reinforced Polymer

. The need for rehabilitation of reinforced concrete structures is rapidly increasing. Fibre reinforced polymer (FRP) composite materials for concrete structures have high strength-to-weight ratios that can provide high prestressing forces while adding minimal additional weight to a structure. They also have good fatigue properties and exhibit low relaxation losses, both of which can increase the service lives and the load carrying capacities of reinforced concrete structures. Carbon fiber reinforced polymer (CFRP) composite system is integrated system based on carbon fibres and epoxy resins. By prestressing the CFRP laminates, the material is used more efficiently as a part of its tensile capacity is utilised and it contributes to the load bearing capacity under both service and ultimate load condition. This is an ideal technique as it combines the advantage of using noncorrosive and lightweight advanced composite material in the form of FRP laminates with high efficiency offered by external prestressing. An innovative mechanical anchorage system was developed to prestress the FRP laminates directly by jacking and reacting against the RCC structure.This paper describes the use of Prestressed CFRP laminates for strengthening of RCC structures including practical applications on slabs and bridges. Also it elucidates the post strengthening testing carried out for the validation of this technique.

scholarly journals Asymptotic Analysis of the MMРР|M|1 Retrial Queue with Negative Calls under the Heavy Load Condition

2020 ◽  
Vol 20 (4) ◽  
pp. 534-547
Author(s):  
Ekaterina A. Fedorova ◽  
◽  
Anatoly A. Nazarov ◽  
Mais P. Farkhadov ◽  
◽  
...  
Keyword(s):  
Asymptotic Analysis ◽  
Retrial Queue ◽  
Load Condition ◽  
System Capacity ◽  
Stationary Mode ◽  
Single Server ◽  
Numerical Comparison ◽  
Heavy Load ◽  
Retrial Queueing System ◽  
Asymptotic Characteristic

In the paper, a single-server retrial queueing system with MMPP arrivals and an exponential law of the service time is studied. Unserviced calls go to an orbit and stay there during random time distributed exponentially, they access to the server according to a random multiple access protocol. In the system, a Poisson process of negative calls arrives, which delete servicing positive calls. The method of the asymptotic analysis under the heavy load condition for the system studying is proposed. It is proved that the asymptotic characteristic function of a number of calls on the orbit has the gamma distribution with the obtained parameters. The value of the system capacity is obtained, so, the condition of the system stationary mode is found. The results of a numerical comparison of the asymptotic distribution and the distribution obtained by simulation are presented. Conclusions about the method applicability area are made.

Effects of Temperature Rise of Grease on Lubricating Performance of Drive Elements under the Extreme Pressure

2021 ◽  
Vol 901 ◽  
pp. 187-192
Author(s):  
Yuh Ping Chang ◽  
Li Ming Chu ◽  
Hsiang Yu Wang ◽  
Chien Te Liu ◽  
Qi Wen Chen
Keyword(s):  
Friction Coefficient ◽  
Temperature Rise ◽  
Electrical Contact ◽  
Load Condition ◽  
Extreme Pressure ◽  
Electrical Contact Resistance ◽  
Heavy Load ◽  
Key Technology ◽  
Effects Of Temperature ◽  
Great Stress

To transfer more power and use it in a heavy load environment, the contact surface between the ball and the track must bear great stress. The temperature always rises due to friction, which is more likely to cause problems of material deformation and fatigue failure. As a result, it will be a key technology to maintain a certain lubricating effect of the transmission components under the environment of heavy load and temperature rise. Through the analysis of friction coefficient and electrical contact resistance, the greases are used to test the lubricating effect of the transmission elements under the heavy load condition. The results will be helpful for the industry to use heavy load greases as a reference.

Sign in / Sign up

Export Citation Format

Share Document