scholarly journals Coupled Vibration Analysis of Submerged Floating Tunnel System in Wave and Current

2018 ◽  
Vol 8 (8) ◽  
pp. 1311 ◽  
Author(s):  
Zhengyang Chen ◽  
Yiqiang Xiang ◽  
Heng Lin ◽  
Ying Yang
Keyword(s):  
Degrees Of Freedom ◽  
Natural Vibration ◽  
Structural Parameters ◽  
Wave Force ◽  
Natural Vibration Frequency ◽  
Governing Equations ◽  
Nonlinear Dynamic Response ◽  
Submerged Floating Tunnel ◽  
Installation Depth ◽  
Tunnel System

Submerged floating tunnel (SFT) is an innovative underwater structure for crossing long straits, which withstands the effects of water wave and current throughout its lifecycle. This paper proposes a theoretical approach to investigate the nonlinear dynamic response of the SFT tube-cable system under combined parametric excitation and hydrodynamic forcing excitations (i.e., wave and vortex-induced loading). Firstly, the governing equations of the SFT system considering the coupled degrees of freedom in the tube and cable are established based on the Hamilton principle and are solved numerically. Then, several representative cases are analyzed to reveal the dynamic characteristics of the SFT. Finally, some key parameters are discussed, such as the wave and current conditions and the structural parameters. The results show that when the flow velocity reaches a certain value, the vortex-induced vibration (VIV) of the anchor-cables will excite a strong resonance in the structure. The displacement amplitude of the SFT increases with the increase of the wave height. Gravity-buoyance ratio (GBR) of the tube and the inclined mooring angle (IMA) of the cables jointly determine the natural vibration frequency of the SFT. The influence of the wave force on the tube is limited when the installation depth of SFT is more than 40 m.

An Experimental Investigation on Cylinder VIV Trajectories Under Different Model Scale

2014 ◽  
Author(s):  
Zh. Kang ◽  
Yunhe Zhai ◽  
Ruxin Song ◽  
Liping Sun
Keyword(s):  
Experimental Investigation ◽  
Vibration Frequency ◽  
Degrees Of Freedom ◽  
Natural Vibration ◽  
Cross Flow ◽  
Small Scale ◽  
Natural Vibration Frequency ◽  
Test Results ◽  
The Cross ◽  
Initial Research

In this paper, model tests were carried out to investigate two degrees of freedom VIV of horizontally-laid cylinders with diameters of 5cm, 11cm, 20cm and length 120cm and compared their vibration trajectories. The test results showed that the in-line and cross-flow vibration frequency of different scale cylinders demonstrate “multi frequency” phenomenon, that is, the in-line vibration frequency is not only twice but also once or four times as much as the cross-flow vibration frequency in some scale, natural frequency and reduced velocity conditions. Also, the cross-flow multi-frequency vibration phenomenon occurred. The trajectory of the vibration cylinder differentiated from the traditional “8” shape accordingly. The vibration trajectory, especially of small-scale cylinder, changed in most conspicuous manner. Through the initial research and analysis, it was found that in addition to in-line and cross-flow natural vibration frequency and the flow velocity, the shape of cylinders was also one of the main causes leading to different vibration trajectory forms.

scholarly journals Dynamic Characteristics Analysis and Experimental Verification of Long Span Suspension Bridge

2021 ◽  
Vol 272 ◽  
pp. 01019
Author(s):  
Guojun Yang ◽  
Qiwei Tian ◽  
Guangwu Tang ◽  
Longlong Li ◽  
Su Ye ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Frequency ◽  
Natural Vibration ◽  
Structural Parameters ◽  
Great Influence ◽  
Suspension Bridge ◽  
Natural Vibration Frequency ◽  
Vibration Modes ◽  
Dead Load ◽  
Long Span

The dynamic characteristics of long-span suspension bridges are complex. The natural vibration frequency is changed with different structural parameters, and the sensitivity to different parameters is different. In order to solve this problem, the spatial model of a long-span suspension bridge was established by using finite element software, and the first 20 natural vibration periods, natural vibration frequencies and vibration modes were analyzed and calculated. The accuracy of the obtained natural vibration frequency data was verified through field tests. Finally, based on the model, the stiffness of structural components is studied by one -factor-at-one-time, and the influence of various variables on the frequency and mode of a certain mode is studied by one-factor-at-one-time method. The results show that different structural parameters have different effects on the vibration frequency. When the stiffness of stiffening girder and main tower is changed, with the increase of stiffness, the variation of frequency mostly presents an upward trend, and the range is large. With the change of the secondary dead load, most of the frequencies decrease first and then tend to be stable. It can be seen from the field test results that the vibration shapes and frequencies measured by numerical simulation and test are close to each other, which can meet the requirements of engineering precision. The stiffness of the main cable and the main tower has a great influence on the modes and periods corresponding to them. The increase of the secondary dead load can reduce the natural vibration frequency of the suspension bridge, but it is not unlimited to increase the secondary dead load to reduce the frequency. The stiffness of the stiffening girder has a great influence on the frequency of the suspension bridge. When the bending stiffness of the stiffening girder increases to 3 times of the original one, the order of vibration modes of the structure will change. The research results can provide references for structural design and dynamic parameter adjustment of long-span suspension bridge.

scholarly journals ANALYSIS THE REACTION OF LIGHTARMOR MACHINES ON THE ACTION OF POLYPULSES FORCES

2021 ◽  
pp. 47-52
Author(s):  
Andrey Grabovskiy ◽  
Mykola M. Tkachuk ◽  
Anatoly Nabokov ◽  
Olexandr Lytvynenko ◽  
Ganna Tkachuk ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Dynamic System ◽  
Degrees Of Freedom ◽  
Natural Vibration ◽  
The Other ◽  
Natural Vibration Frequency ◽  
Stabilization System ◽  
Recoil Force ◽  
The One ◽  
High Level

In modern conditions, lightarmored vehicles with powerful weapon modules are widely used in the armies of different countries. These modules are equipped with small-caliber automatic cannons, which have a rate of fire of several hundred rounds per minute and a high level of recoil forces. Moreover, there are tendencies towards an increase in the rate of fire and the caliber of weapons (and, accordingly, recoil forces). Considering that weapon modules rely on the lightarmored vehicles skeleton, which has higher responsiveness characteristics than heavy combat vehicles in terms of weight, the problem of determining the reaction of the «weapon module - armored hull - suspension» system to the action of recoil forces in order to ensure on the one hand, the strength of armored hulls, and on the other hand, reducing the load on the guidance and stabilization system of weapons during firing.To study the response of elements of lightly armored vehicles to the action of recoil forces when firing a burst of combat modules, numerous models have been built with a small number of degrees of freedom. Using these models, the reaction of a dynamic system to the action of a number of impulses was investigated.These impulses caused by the action of recoil forces when firing shots from combat modules. Keywords: lightlyarmored vehicle; weapon module; small-bore automatic cannon; recoil force targeting and weapon stabilization system; dynamic system; numerical modeling; method of finite elements; natural vibration frequency

Research on the Piezoelectric Ultrasonic Actuator Applied to SFSS

2015 ◽  
Author(s):  
Y. J. Tang ◽  
Z. Yang ◽  
X. J. Wang ◽  
J. Wang
Keyword(s):  
Natural Vibration ◽  
Structural Parameters ◽  
Laser Vibrometer ◽  
Vibration Modes ◽  
Element Analysis ◽  
Linear Type ◽  
Frequency Sweep ◽  
The Finite Element Analysis ◽  
Frequency Sweep Test ◽  
Overall Performance

This paper presents an investigation of a novel linear-type piezoelectric ultrasonic actuator for application in a Smart Fuze Safety System (SFSS). Based on the requirements of SFSS, the structural parameters of the proposed piezoelectric ultrasonic actuator are determined by fuze arming mode. Moreover, sensitivity analysis of the structural parameters to the frequency consistency is conducted using FEM software, after which the optimal dimensions are obtained with two close natural vibration frequencies. To validate the results of FEM, the frequency sweep tests of the piezoelectric ultrasonic actuator are performed to determine the motor’s actual working mode frequencies with PSV-300-B Doppler laser vibrometer system. Furthermore, the results of frequency sweep test are compared with that of the finite element analysis, and further verified by impedance analyzer. To investigate the overall performance of the piezoelectric ultrasonic actuator, vibration modes of actuator’s stator, output speed and force of the piezoelectric ultrasonic actuator are tested. The experimental results show that the output speed and force of the actuator can reach 88.2 mm/s and 2.3N respectively, which means that piezoelectric ultrasonic actuator designed in this paper can meet the demands of the SFSS.

The Application of BESO in Vibration Damping of Ship Plate

2013 ◽  
Vol 572 ◽  
pp. 185-188 ◽  
Author(s):  
Xiao Yan Teng ◽  
Jia Shan Han ◽  
Liang Peng
Keyword(s):  
Natural Vibration ◽  
Target Function ◽  
Vibration Damping ◽  
Natural Vibration Frequency ◽  
Constraint Condition ◽  
Evolutionary Structural Optimization ◽  
Damping Material ◽  
Reasonable Result ◽  
Beso Method ◽  
Original Amount

Based on the bi-directional evolutionary structural optimization (BESO), the method of determining the adhesion position of the damping material is proposed in this paper, which is applicable to the vibration damping of ship plate. In this method, the needed amount of damping material is taken as the constraint condition, and the maximization of one natural vibration frequency of the structure is taken as the target function. A thin plate structure with both ends constraints has been taken as an example to get the best topology structure of its adhesion damper by taking the BESO method. The result of optimization shows that it still meets the damping requirements when the needed amount of damping material decreases by about 50% of the original amount. The reasonable result demonstrates the effectiveness and engineering value of the method.

Numerical and Experimental Approaches to Investigate the Stability of a Motorcycle Vehicle

2006 ◽  
Author(s):  
Federico Cheli ◽  
Marco Bocciolone ◽  
Marco Pezzola ◽  
Elisabetta Leo
Keyword(s):  
Degrees Of Freedom ◽  
Structural Parameters ◽  
Experimental Tests ◽  
Roll Angle ◽  
Longitudinal Motion ◽  
Reference Trajectory ◽  
Steering Angle ◽  
Steady State Condition ◽  
The Stability ◽  
Linearized Model

The study of motorcycle’s stability is an important task for the passenger’s safety. The range of frequencies involved for the handling stability is lower than 10 Hz. A numerical model was developed to access the stability of a motorcycle vehicle in this frequency range. The stability is analysed using a linearized model around the straight steady state condition. In this condition, the vehicle’s vertical and longitudinal motion are decoupled, hence the model has only four degrees of freedom (steering angle, yaw angle, roll angle and lateral translation), while longitudinal motion is imposed. The stability was studied increasing the longitudinal speed. The input of the model can be either a driver input manoeuvre (roll angle) or a transversal component of road input able to excite the vibration modes. The driver is introduced in the model as a steering torque that allows the vehicle to follow a reference trajectory. To validate the model, experimental tests were done. To excite the vehicle modes, the driver input was not taken into account considering both the danger for the driver and the repeatability of the manoeuvre. Two different vehicle configurations were tested: vehicle 1 is a motorcycle [7] and vehicle 2 is a scooter. Through the use of the validated model, a sensitivity analysis was done changing structural (for example normal trail, steering angle, mass) and non structural parameters (for example longitudinal speed).

DESIGN AND DEVELOPMENT OF AN EFFICIENT COMPUTER SIMULATION MODEL FOR RESPONSE ANALYSIS OF A MOORED SEMI-SUBMERSIBLE

2021 ◽  
Vol 161 (A1) ◽  
Author(s):  
V Domala ◽  
R Sharma
Keyword(s):  
Computer Simulation ◽  
Simulation Model ◽  
Degrees Of Freedom ◽  
Experimental Results ◽  
Response Analysis ◽  
Computer Simulation Model ◽  
Governing Equations ◽  
Design And Development ◽  
Mooring Lines ◽  
Steel Wires

This paper presents the design and development of an efficient modular ‘Computer Simulation Model (CSM)’ for response analysis of a moored semi-submersible. The computer simulation model is designed in two split models (i.e. computational and experimental models) and each of these models consists of various modules. The modules are developed from basic governing equations related to motion and modules are integrated and we aim for a seamless integration. The moored semi-submersible is represented mathematically as six degrees of freedom dynamic system and the coupling effects between the structure and mooring lines are considered. The basic geometric configuration of semi- submersible is modelled and analyzed for stability computations in MS-Excel*TM and then the basic governing equations related to motion are modelled mathematically in a module and solved numerically with Ansys-AQWA**TM. The computational model is validated and verified with some available experimental results. The CSM is utilized to study the surge and sway responses with respect to the horizontal range of mooring lines and our results show good validation with the existing experimental results. Our presented results show that the fibre wires have minimum steady state response in surge and sway degrees of freedom as compared with the steel wires. However, they have large drift as compared with steel wires. Finally, we show that the computer simulation model can help in detailed analysis of responses and results can be utilized for design and development of new age semi-submersibles for optimum performances for a given set of parameters.

Theoretical and Experimental Study of the Nonlinearly Coupled Heave, Pitch, and Roll Motions of a Ship in Longitudinal Waves

1993 ◽  
Author(s):  
I. G. Oh ◽  
A. H. Nayfeh ◽  
D. T. Mook
Keyword(s):  
Large Amplitude ◽  
Degrees Of Freedom ◽  
Excitation Frequency ◽  
Force Response ◽  
Governing Equations ◽  
Response Curves ◽  
Varying Coefficients ◽  
Jump Phenomena ◽  
Time Varying Coefficients ◽  
Three Degrees Of Freedom

Abstract The loss of dynamic stability and the resulting large-amplitude roll of a vessel in a head or following sea were studied theoretically and experimentally. A ship model with three degrees of freedom (roll, pitch, heave) was considered. The governing equations for the heave and pitch modes were linearized and their harmonic solutions were coupled with the nonlinear equation governing roll. The resulting equation, which has time-varying coefficients, was used to predict the response in roll. The principal parametric resonance was considered in which the excitation frequency is twice the natural frequency in roll. Force-response curves were obtained. The existence of jump phenomena and multiple stable solutions for the case of subcritical instability was observed in the experiments and found to be in good qualitative agreement with the results predicted by the theory. The experiments also revealed that the large-amplitude roll is dependent on the location of the model in the standing waves.

Study on the Influence of Reactor Core Structure on Reactor Natural Vibration Frequency

2021 ◽  
Author(s):  
Yuan Zhou ◽  
Tian Tian ◽  
Xiongfei Yu ◽  
Ran Ren ◽  
Liangcai Zhou ◽  
...  
Keyword(s):  
Vibration Frequency ◽  
Natural Vibration ◽  
Reactor Core ◽  
Core Structure ◽  
Natural Vibration Frequency
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