Time Domain Analysis of Single Module Movement of Deep Sea Rights Enforcement Platform

2020 ◽  
Author(s):  
Wang Yuhan ◽  
Yuan Hongtao ◽  
Kong Weiwen ◽  
Yang Hankun ◽  
Zhang Huan
Keyword(s):  
Deep Sea ◽  
Response Spectrum ◽  
Time Domain Analysis ◽  
Element Model ◽  
Parameter Analysis ◽  
Asymmetric Structure ◽  
Wave Direction ◽  
Hydrodynamic Coefficient ◽  
Motion Response ◽  
Wave Cycle

Abstract Due to its large size, deep sea rights enforcement platform cannot be closed in the dock, so it needs to be dragged to the pre-installed position for module to module connection. Based on the ANSYS AQWA software, a single module finite element model of the platform is established to solve the security problem of the far-reaching maritime rights enforcement platform in the sea. The hydrodynamic coefficient and the transfer function of the motion response are calculated in the frequency domain, and the response spectrum analysis is carried out. It is worth noting that the single module is a trapezoidal asymmetric structure, so the shape influence on the calculation results will be focused on. The results show that the motion response of the single module is greatly influenced by the wave cycle and the wave direction, because the single module of the platform is a trapezoid asymmetric structure, and the hydrodynamic coefficients are different under different incident waves. Through comparison and parameter analysis, the rationality of the single module design and the good motion performance under the actual sea condition are verified.

An Effective Method for Determining Finite Element Model Parameters of Rotor Elastic Support System

2011 ◽  
Vol 141 ◽  
pp. 191-197
Author(s):  
Yong Xing Wang ◽  
Jiang Yan ◽  
Sheng Ze Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Support System ◽  
Structural Parameters ◽  
Element Model ◽  
Elastic Support ◽  
Asymmetric Structure ◽  
Model Parameters ◽  
Equivalent Stiffness ◽  
Rolling Ball

A finite element model of the elastic support rotor system based on the corresponding experimental model was established. According to the principle of two types of model with an equal first order critical speed, the equivalent stiffness and damping of a rolling ball bearing support system with rubber rings determined by experiment were transferred into the finite element model. Then, the dynamic behavior of rotor systems with symmetric and asymmetric structure, different support system stiffness and support span were calculated and analyzed respectively. At last, the influence of the rotor structural parameters on the equivalent stiffness of elastic bearing support system obtained by experiment was pointed out.

Numerical Simulation on Mooring Performance of LNG-FPSO System in Realistic Seas

2005 ◽  
Author(s):  
Yoshiyuki Inoue ◽  
Md. Kamruzzaman
Keyword(s):  
Time Domain ◽  
Oil And Gas ◽  
Three Dimensional ◽  
Time Domain Analysis ◽  
Analysis Tool ◽  
Motion Response ◽  
Non Linear ◽  
Floating System ◽  
Exciting Forces ◽  
The Time Domain

The LNG-FPSO concept is receiving much attention in recent years, due to its active usage to exploit oil and gas resources. The FPSO offloads LNG to an LNG carrier that is located close to the FPSO, and during this transfer process two large vessels are in close proximity to each other for daylong periods of time. Due to the presence of neighboring vessel, the motion response of both the vessels will be affected significantly. Hydrodynamic interactions related to wave effects may result in unfavorable responses or the risk of collisions in a multi-body floating system. Not only the motion behavior but also the second order drift forces are influenced by the neighboring structures due to interactions of the waves among the structures. A study is made on the time domain analysis to assess the behavior and the operational capability of the FPSO system moored in the sea having an LNG carrier alongside under environmental conditions such as waves, wind and currents. This paper presents an analysis tool to predict the dynamic motion response and non-linear connecting and mooring forces on a parallel-connected LNG-FPSO system due to non-linear exciting forces of wave, wind and current. Simulation for the mooring performance is also investigated. The three-dimensional source-sink technique has been applied to obtain the radiation forces and the transfer function of wave exciting forces on floating multi-bodies. The hydrodynamic interaction effect between the FPSO and the LNG carrier is included to calculate the hydrodynamic forces. For the simulation of a random sea and also for the generation of time depended wind velocity, a fully probabilistic simulation technique has been applied. Wind and current loads are estimated according to OCIMF. The effects of variations in wave, wind and current loads and direction on the slowly varying oscillations of the LNG and FPSO are also investigated in this paper. Finally, some conclusions are drawn based on the numerical results obtained from the present time domain simulations.

scholarly journals Structural Health Monitoring of the Scaffolding Dismantling Process of a Long-Span Steel Box Girder Viaduct Based on BOTDA Technology

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Yong Ding ◽  
Feng Xiao ◽  
Weiwei Zhu ◽  
Tao Xia
Keyword(s):  
Health Monitoring ◽  
Strain Distribution ◽  
Time Domain Analysis ◽  
Element Model ◽  
Box Girder ◽  
Bridge Health Monitoring ◽  
Long Span ◽  
Steel Box Girder ◽  
Optical Time ◽  
Distributed Optical Fiber

In this study, a distributed optical fiber sensing technique based on Brillouin optical time-domain analysis (BOTDA) is used to construct a complete bridge health monitoring system by continuously laying distributed sensing fiber lines in a steel box girder. The bridge scaffolding dismantling process is monitored to study the variation of the strain distribution. Additionally, a bridge finite element model is built to simulate the bridge scaffolding removed condition, and the strain distribution of the long-span steel box girder viaduct after scaffolding dismantling is compared with the measured values. This study provides a reference for monitoring the scaffolding dismantling process based on BOTDA technology.

scholarly journals Influence of Soil Parameters on Detecting Voids behind a Tunnel Lining Using an Impact Echo Method

2019 ◽  
Vol 9 (24) ◽  
pp. 5403
Author(s):  
Meng Ma ◽  
Rongning Cao ◽  
Chao Niu ◽  
Hougui Zhang ◽  
Weining Liu
Keyword(s):  
Element Model ◽  
Tunnel Lining ◽  
Parameter Analysis ◽  
Soil Parameters ◽  
Impact Echo ◽  
Time Frequency ◽  
Box Counting ◽  
Box Counting Dimension ◽  
Frequency Domains ◽  
The Impact

Tunnel lining cavities are a common problem that may affect the bearing capacity of the tunnel-supporting structure, as well as the tunnel service life. The impact echo (IE) method can be used to detect voids behind tunnel linings. For a long tunnel, the surrounding rocks/soils are inhomogeneous and anisotropic, with parameters that vary with tunnel mileages. It is interesting to analyse whether alterations of the soil parameters affect the non-destructive test results. A laboratory experiment was performed in this study, in which voids behind a concrete plate, representing the tunnel lining, were designed to model the ineffective contact between the soil and the tunnel. The IE method was employed to inspect the existence of the void using different signal analysis approaches in the time, frequency and time–frequency domains. Furthermore, the fractal box-counting dimension was calculated for the purpose of quantitative evaluation. Different soil parameters and void sizes were considered, and finally, a finite element model was built and parameter analysis was accomplished using the software ABAQUS. The results demonstrated that: (1) A comprehensive analysis of vibration signals in the time, frequency and time–frequency domains was useful for identifying voids, while the box-counting dimension was useful for evaluating voids quantitatively. (2) Soils with large density and Young’s modulus differences had a certain influence on void detection, while those with large water content and Poisson’s ratio differences had little influence. (3) The box-counting dimension value was stable within the area where the void existed behind the tunnel; when the detection point was beyond twice that of the void dimension, it was difficult to locate the void.

Vibration and Sound Radiation Characteristics of Composite Flat-Panel Sound Radiator

2013 ◽  
Vol 431 ◽  
pp. 177-181
Author(s):  
C.H. Jiang ◽  
T.Y. Kam
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Response Spectrum ◽  
Sound Radiation ◽  
Laminated Composite ◽  
Element Model ◽  
Flat Panel ◽  
Radiation Characteristics ◽  
Experimental Approaches ◽  
Vibration And Sound Radiation

The vibration and sound radiation characteristics of laminated composite flat-panel sound radiators are studied via both theoretical and experimental approaches. In the theoretical study, a finite element model is presented to formulate the forced vibration of the sound radiators. The first Rayleigh integral is used to construct the sound pressure level curve of the sound radiators. In the experimental study, a laminated composite sound radiator was subjected to sweep sine excitation to determine the frequency response spectrum from which the natural frequencies of the sound radiator were identified. The sound radiator with salt powder distributed on its top surface was excited to generate the vibration shapes of the sound radiator at several selected frequencies. The SPL curve of the sound radiator was also measured experimentally. The experimental results are then used to verify the feasibility and accuracy of the proposed finite element model.

Evaluation of Seismic Integrity for an Integral Reactor Assembly

2004 ◽  
Author(s):  
Soon Myeon Wang ◽  
J. S. Kim ◽  
T. E. Jin ◽  
M. J. Jhung ◽  
Y. H. Choi ◽  
...  
Keyword(s):  
Modal Analysis ◽  
Seismic Analysis ◽  
Coupling Effect ◽  
Response Spectrum ◽  
Safety Margin ◽  
Time History ◽  
Element Model ◽  
Seismic Safety ◽  
Reactor Assembly ◽  
Integral Reactor

The structural integrity of integral reactor assembly of 65Mwt thermal capacity is assessed by using the commercial finite element package ANSYS in order to evaluate the seismic safety margin. First of all, the modal analyses are performed using the various analysis models with/without the fluid coupling effect in order to validate a super element model and to evaluate the coupling effect on natural frequency. Based on the modal analysis results, the seismic analyses are performed using the ground response spectrum defined in Reg. Guide 1.60. Finally, time-history analyses are performed using the modal analysis results, the super element model and an inertia load approach. As a result, the reliable and efficient seismic analysis model for an integral reactor assembly is developed and it is found that an integral reactor assembly has the sufficient seismic safety margin.

scholarly journals Numerical simulation of pounding damage to caisson under storm surge

2018 ◽  
Vol 38 ◽  
pp. 03046
Author(s):  
Chen Yu
Keyword(s):  
Numerical Simulation ◽  
Storm Surge ◽  
Failure Mode ◽  
Structural Model ◽  
Time History ◽  
Element Model ◽  
Wave Force ◽  
New Method ◽  
Wave Direction ◽  
Force Time

In this paper, a new method for the numerical simulation of structural model is proposed，which is employed to analyze the pounding response of caissons subjected to storm surge loads．According to the new method，the simulation process is divided into two steps. Firstly, the wave propagation caused by storm surge is simulated by the wave-generating tool of Flow-3D, and recording the wave force time history on the caisson. Secondly，a refined 3D finite element model of caisson is established，and the wave force load is applied on the caisson according to the measured data in the first step for further analysis of structural pounding response using the explicit solver of LSDYNA. The whole simulation of pounding response of a caisson caused by “Sha Lijia” typhoon is carried out. The results show that the different wave direction results in the different angle caisson collisions, which will lead to different failure mode of caisson, and when the angle of 60 between wave direction and front/back wall is simulated, the numerical pounding failure mode is consistent with the situation.

Influence of ossicular chain malformation on the performance of round-window stimulation: A finite element approach

2019 ◽  
Vol 233 (5) ◽  
pp. 584-594 ◽  
Author(s):  
Houguang Liu ◽  
Hu Zhang ◽  
Jianhua Yang ◽  
Xinsheng Huang ◽  
Wen Liu ◽  
...  
Keyword(s):  
Finite Element ◽  
Middle Ear ◽  
Basilar Membrane ◽  
Round Window ◽  
Low Frequency ◽  
Element Model ◽  
Ossicular Chain ◽  
Asymmetric Structure ◽  
Low Frequencies ◽  
Stapes Fixation

As a novel application of implantable middle ear hearing device, round-window stimulation is widely used to treat hearing loss with middle ear disease, such as ossicular chain malformation. To evaluate the influence of ossicular chain malformations on the efficiency of the round-window stimulation, a human ear finite element model, which incorporates cochlear asymmetric structure, was constructed. Five groups of comparison with experimental data confirmed the model’s validity. Based on this model, we investigated the influence of three categories of ossicular chain malformations, that is, incudostapedial disconnection, incus and malleus fixation, and fixation of the stapes. These malformations’ effects were evaluated by comparing the equivalent sound pressures derived from the basilar membrane displacement. Results show that the studied ossicular chain malformations mainly affected the round-window simulation’s performance at low frequencies. In contrast to the fixation of the ossicles, which mainly deteriorates round-window simulation’s low-frequency performance, incudostapedial disconnection increases this performance, especially in the absence of incus process and stapes superstructure. Among the studied ossicular chain malformations, the stapes fixation has a much more severe impact on the round-window stimulation’s efficiency. Thus, the influence of the patients’ ossicular chain malformations should be considered in the design of the round-window stimulation’s actuator. The low-frequency output of the round-window simulation’s actuator should be enhanced, especially for treating the patients with stapes fixation.

scholarly journals An Artificial Seismic Wave Suitable for Suspended Converter Valve in the UHVDC Transmission Project

2019 ◽  
Vol 118 ◽  
pp. 02039
Author(s):  
Jin Xiao ◽  
Mingduo Huang ◽  
Qiguo Sun
Keyword(s):  
Finite Element ◽  
Seismic Wave ◽  
Seismic Design ◽  
Response Spectrum ◽  
Time History ◽  
Element Model ◽  
Series Method ◽  
Long Period ◽  
Standard Response ◽  
The Finite Element Model

The finite element model of suspended converter valve in an UHVDC transmission project with characteristics of flexible is constructed, and its vibration characteristics are simulated and analyzed firstly. The results show that this kind of suspended converter valve has obvious long-period character. Secondly, the long period phase of standard response spectrum in Code for Seismic Design of Buildings (GB50011-2010) is modified, and then the artificial seismic wave is synthesized employing the triangular series method. The result shows that this artificial seismic wave has long-period character. Finally, the time-history seismic dynamic simulation of the converter valve is done, and the seismic responses of the converter valve excited by three kinds of seismic wave with different period characters are compared and analyzed. The results show that the swing and stress of the suspended converter valve are larger under the long-period seismic wave synthesized in this paper. The quasi-resonance damage caused by long-period seismic wave should be concerned specially in the actual UHVDC transmission project.

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