Dynamic characteristics of a slender flexible cylinder excited by concomitant vortex-induced vibration and time-varying axial tension

2020 ◽  
Vol 485 ◽  
pp. 115524
Author(s):  
Yexuan Ma ◽  
Wanhai Xu ◽  
Tao Pang ◽  
Qicheng Wang ◽  
Jiang Lai
Keyword(s):  
Dynamic Characteristics ◽  
Time Varying ◽  
Flexible Cylinder ◽  
Vortex Induced Vibration ◽  
Axial Tension

The effect of time-varying axial tension on VIV suppression for a flexible cylinder attached with helical strakes

2021 ◽  
Vol 241 ◽  
pp. 109981
Author(s):  
Yexuan Ma ◽  
Wanhai Xu ◽  
Huanan Ai ◽  
Yingying Wang ◽  
Kun Jia
Keyword(s):  
Time Varying ◽  
Flexible Cylinder ◽  
Axial Tension ◽  
Helical Strakes ◽  
Viv Suppression

VIV Response and Fatigue Damage of Flexible Cylinders With Time-Varying Axial Tension

2018 ◽  
Author(s):  
Yuan Yuchao ◽  
Xue Hongxiang ◽  
Tang Wenyong ◽  
Liu Jun
Keyword(s):  
Fatigue Damage ◽  
Structural Response ◽  
Design Stage ◽  
Small Scale ◽  
Time Varying ◽  
Flexible Cylinder ◽  
Time Step ◽  
Response Characteristics ◽  
Axial Tension ◽  
Tension Time

The time-varying effect of axial tension has recently attracted increasing focus when investigating vortex-induced vibration (VIV) for flexible cylinders. This paper applies an alternative time domain force–decomposition model to predict VIV response, in which the structural stiffness will be updated at each time step to take the tension variation into account. Firstly, the adopted numerical model is compared against the latest published experimental results of a small-scale cylinder with constant and time-varying tensions. Then, extensive cases of a long flexible cylinder are designed to investigate the tension time-varying effect on structural response and fatigue damage respectively. Several new response characteristics different from the constant tension case are analyzed from the VIV mechanism level. Fatigue analysis also reveals the influence laws of the amplitude and frequency of varying tension. Mathieu-type resonance between VIV and time-varying tension excitation is captured, under which structural response as well as fatigue damage will enlarge significantly. Some conclusions drawn by this research can provide reference at the engineering design stage of marine slender structures.

Research on dynamic characteristics of gear system considering the influence of temperature on material performance

2021 ◽  
pp. 107754632110026
Author(s):  
Zhou Sun ◽  
Siyu Chen ◽  
Xuan Tao ◽  
Zehua Hu
Keyword(s):  
Elastic Modulus ◽  
Dynamic Characteristics ◽  
Poisson’S Ratio ◽  
Gear System ◽  
Poisson's Ratio ◽  
Effect Of Temperature ◽  
Time Varying ◽  
Influence Of Temperature ◽  
Meshing Stiffness ◽  
Influence Of Temperature On

Under high-speed and heavy-load conditions, the influence of temperature on the gear system is extremely important. Basically, the current work on the effect of temperature mostly considers the flash temperature or the overall temperature field to cause expansion at the meshing point and then affects nonlinear factors such as time-varying meshing stiffness, which lead to the deterioration of the dynamic transmission. This work considers the effect of temperature on the material’s elastic modulus and Poisson’s ratio and relates the temperature to the time-varying meshing stiffness. The effects of temperature on the elastic modulus and Poisson’s ratio are expressed as functions and brought into the improved energy method stiffness calculation formula. Then, the dynamic characteristics of the gear system are analyzed. With the bifurcation diagram, phase, Poincaré, and fast Fourier transform plots of the gear system, the influence of temperature on the nonlinear dynamics of the gear system is discussed. The numerical analysis results show that as the temperature increases, the dynamic response of the system in the middle-speed region gradually changes from periodic motion to chaos.

scholarly journals Analysis of Dynamic Characteristics of a Propeller Blade Subjected to Large Material Removal in Milling

2020 ◽  
pp. 10-14
Author(s):  
Luyi Han ◽  
◽  
Riliang Liu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Behavior ◽  
Dynamic Characteristics ◽  
Material Removal ◽  
Natural Frequencies ◽  
Machining Process ◽  
Time Varying ◽  
Propeller Blade ◽  
Large Material

A propeller blade, as a typical example of low-rigidity components, is prone to chatter and deformation in machining process, especially when large material removal is applied. In order to foresee the problems and then optimize the process, identification of the dynamic behavior of the workpiece is of great importance. This paper studies the dynamic characteristics of the workpiece in the machining process from plate to propeller blade using Finite Element Method. The results show that the time-varying natural frequencies of the workpiece decrease gradually at the beginning steps of the process due to the influence of material removal, and increases afterwards influenced by the geometry of the blade.

Study on the Dynamic Characteristics of the Winding Head

2016 ◽  
Vol 693 ◽  
pp. 213-220
Author(s):  
Jiang Yan ◽  
Yong Xing Wang ◽  
Su Jia Li ◽  
Xi Hou ◽  
Sheng Ze Wang
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Filament Winding ◽  
Time Varying ◽  
Working Process ◽  
Coupling Stiffness ◽  
Spindle Structure ◽  
Full Volume ◽  
Stiffness Coupling

According to the structure and production processing requirements of polyester filament winding head, a finite element dynamic model of the winding system in parameters time-varying was established. By using the method of numerical calculation, the dynamic characteristics of the winding head were analyzed in three processes: rapid starting-up in empty volume, winding filament process and stopping in full volume. By studying the influence of the three processing under large stiffness coupling and soft stiffness coupling in the winding head, the role of the coupling stiffness and spindle structure was revealed in different working process.

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