scholarly journals A Three-Dimensional Lumped Mass Method for the Dynamic Analysis of Mooring Lines

1983 ◽  
Vol 1983 (154) ◽  
pp. 192-202 ◽  
Author(s):  
Toshio Nakajima ◽  
Seizo Motora ◽  
Masataka Fujino
Keyword(s):  
Dynamic Analysis ◽  
Three Dimensional ◽  
Lumped Mass ◽  
Mooring Lines ◽  
Lumped Mass Method

Three-Dimensional Dynamic Analysis Method of Multi-Component Mooring Lines

2019 ◽  
Author(s):  
Yuda Apri Hermawan ◽  
Yoshitaka Furukawa
Keyword(s):  
Dynamic Analysis ◽  
Numerical Method ◽  
Three Dimensional ◽  
Experimental Results ◽  
Mooring Line ◽  
Lumped Mass ◽  
Mooring Lines ◽  
Dynamic Behaviors ◽  
Component Object ◽  
Deep Depth

Abstract Complicated mooring system well-known as a multi-component mooring line is highly required owing to the deep depth of water and severe sea conditions. Since the dynamic behaviors of such mooring line are quite complex, proper numerical method is indispensable to predict the dynamic behaviors of a multi-component mooring line efficiently and precisely. In this paper, a numerical method improving the lumped mass method is proposed to introduce the three-dimensional dynamic analysis of multi-component mooring line with the motion of an anchor and clump weights. The mooring line is regarded as a multi-component object which has nonuniform segment line characteristics. In this method, lumped mass technique is developed to represent the three-dimensional dynamic behavior of each segment individually, allowing the motion of bottom-end segment as well as the anchor. Then, the motion of the end-segment is regarded as the motion of the upper-end of lower segment. Meanwhile, calculation method of initial condition for dynamic calculation is developed by adopting the basic principle of multi-component mooring line catenary equations. The results of time histories representing the three-dimensional dynamic analysis of mooring line are obtained and compared with other numerical and experimental results presented in published papers. The results show good agreement with both numerical and experimental results.

scholarly journals Time and Frequency Domain Dynamic Analysis of Offshore Mooring

2021 ◽  
Vol 9 (7) ◽  
pp. 781
Author(s):  
Shi He ◽  
Aijun Wang
Keyword(s):  
Dynamic Analysis ◽  
Frequency Domain ◽  
Time Domain ◽  
Linearization Method ◽  
Euler Method ◽  
Single Component ◽  
Hydrodynamic Drag ◽  
Lumped Mass ◽  
Mooring Lines ◽  
The Time Domain

The numerical procedures for dynamic analysis of mooring lines in the time domain and frequency domain were developed in this work. The lumped mass method was used to model the mooring lines. In the time domain dynamic analysis, the modified Euler method was used to solve the motion equation of mooring lines. The dynamic analyses of mooring lines under horizontal, vertical, and combined harmonic excitations were carried out. The cases of single-component and multicomponent mooring lines under these excitations were studied, respectively. The case considering the seabed contact was also included. The program was validated by comparing with the results from commercial software, Orcaflex. For the frequency domain dynamic analysis, an improved frame invariant stochastic linearization method was applied to the nonlinear hydrodynamic drag term. The cases of single-component and multicomponent mooring lines were studied. The comparison of results shows that frequency domain results agree well with nonlinear time domain results.

A Simplified Model of SSI Dynamic Analysis

2012 ◽  
Vol 446-449 ◽  
pp. 334-339
Author(s):  
Zhi Ying Zhang ◽  
Ying Li ◽  
Qing Sun
Keyword(s):  
Dynamic Analysis ◽  
Soil Structure ◽  
Design Method ◽  
Simplified Model ◽  
Lumped Mass ◽  
Foundation Soil ◽  
Linear Elastic ◽  
Lumped Mass Method ◽  
Actual Mechanism ◽  
Seismic Design Method

Aiming at the problem of dynamic analysis of SSI system, the dynamic influence of different parts of foundation soil is studied on the linear elastic assumption according to the actual mechanism of Soil-Structure Interaction (SSI); in addition, a simplified model on the condition of the lumped mass method is put forward and the corresponding motion equations of SSI system are built, which can be a reference for the structural seismic design method considering SSI effect.

Research on Influence of Horizontal Offsets of Underwater Equipment Based on Pendulous Installation Method

2018 ◽  
Author(s):  
Jingqian Wang ◽  
Liping Sun ◽  
Zhongchao Deng ◽  
Gang Ma ◽  
Xiaomeng Zhu ◽  
...  
Keyword(s):  
Deep Water ◽  
Water Environment ◽  
Three Dimensional ◽  
Mooring Line ◽  
Analysis Model ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Traction Fluid ◽  
Simulation Problem ◽  
Domain Coupling

Large underwater equipment used in deep-sea engineering, which needs mooring line in order to hang down while using pendulous installation method in 1500m deep-water installation. During the procession, the mooring line will suffer the vessel’s pull, large equipment’s traction, fluid force leading to elongation, bending and other deformation, so need to analyze its motion. Aiming at the numerical simulation problem of underwater equipment installed by pendulous installation method in deep-water environment, this paper combines lumped mass method, three-dimensional potential theory and Morison equation to establish the analysis model of the whole installation system. Under the different horizontal dropping offsets of the equipment, this paper computes not only tension of mooring line, but motion performance of underwater equipment and working vessel during the pendulous lowering phase. The Pendulous Installation Method (PIM) puts a working vessel, a mooring line and a underwater equipment installed in succession, and there is a coupling interaction among them, so it is essential to do time-domain coupling analysis. So the Orcaflex Software is used to simulate the entire deep-water installation system. Using different horizontal dropping position as a variable, we can get the contrast about the different movement states of the mooring line and underwater equipment, and finally we will get the conclusion.

Dynamic analysis of finger seal using equivalent model based on distributed mass method

2014 ◽  
Vol 228 (16) ◽  
pp. 2992-3005 ◽  
Author(s):  
Guo-Ding Chen ◽  
Fei Lu ◽  
Qiang-Peng Yu ◽  
Hua Su
Keyword(s):  
Dynamic Analysis ◽  
Equivalent Model ◽  
Leakage Flow ◽  
Lumped Mass ◽  
Model Based ◽  
Lumped Mass Method ◽  
Leakage Flow Rate ◽  
Dynamic Performances ◽  
Contact Pressures ◽  
Good Agreement

Dynamic analysis of finger seal can be performed by finite element method or equivalent model based on lumped mass method now available, which is difficult in meeting both the acceptable calculation time and accuracy simultaneously. For this reason, interactions between finger elements are considered and the equivalent dynamic model based on distributed mass method is proposed in this article. Seal dynamic performances are obtained by using this model to calculate the equivalent parameters, air leakage flow, and the contact behavior between finger seal and the rotor. The work to be presented here concerns the mapping of dynamic behavior of the finger seal with a stack of three finger elements, including the dynamic displacement responses of finger elements, the leakage clearances, and the contact pressures between the finger elements and the rotor, as well as the leakage flow rate and the wear rate. The results calculated by the equivalent model presented in this study are evaluated by comparison with the published experimental data and results from the model based on lumped mass method, which shows that the equivalent model based on distributed mass method is far superior to that based on lumped mass method because the calculations are in good agreement with the experimental results.

3-D LUMPED MASS METHOD OF DYNAMIC ANALYSIS FOR HIGH-RISE BUILDING

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Zorigt Tumurbaatar ◽  
Haruyuki Yamamoto
Keyword(s):  
Dynamic Analysis ◽  
Stiffness Matrix ◽  
Structural Response ◽  
Building Structures ◽  
Lumped Mass ◽  
Total Size ◽  
Building Model ◽  
High Rise ◽  
High Rise Building ◽  
Lumped Mass Method

This study is related to decreasing size of stiffness matrix of high-rise building by using floor diaphragm constraints. The combined actions of horizontal structural members such as slab and beams produce structural response that is much stiffer than vertical elements such as columns. In structural analysis of high-rise building model, absolute rigid slab and vertical structure are working together for lumped mass method. Each lumped mass node has 6 degree of freedoms which is very suitable for high-rise building calculation. The lumped mass is consisted of slab and beams, on the other hand the system’s stiffness matrix is only assembly of columns and braces. High-rise building lumped mass model’s stiffness matrix size is n=6 x m (n; total size of stiffness matrix, m; total floor number). In the step by step calculation, total unknown number is decrease enough which means we can easily calculate high-rise building structures for dynamic analysis also nonlinear step by step calculation using simple personal computer. If building model has large span and short height, in this case rigid slab theory will not satisfied. This idea is more suitable for high-rise building calculation.

Dynamic analysis of a helical gear reduction by experimental and numerical methods

2020 ◽  
Vol 68 (1) ◽  
pp. 48-58
Author(s):  
Chao Liu ◽  
Zongde Fang ◽  
Fang Guo ◽  
Long Xiang ◽  
Yabin Guan ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Fourth Order ◽  
Numerical Models ◽  
Helical Gear ◽  
Operating Conditions ◽  
Dynamic Responses ◽  
Lumped Mass ◽  
Gear Mesh

Presented in this study is investigation of dynamic behavior of a helical gear reduction by experimental and numerical methods. A closed-loop test rig is designed to measure vibrations of the example system, and the basic principle as well as relevant signal processing method is introduced. A hybrid user-defined element model is established to predict relative vibration acceleration at the gear mesh in a direction normal to contact surfaces. The other two numerical models are also constructed by lumped mass method and contact FEM to compare with the previous model in terms of dynamic responses of the system. First, the experiment data demonstrate that the loaded transmission error calculated by LTCA method is generally acceptable and that the assumption ignoring the tooth backlash is valid under the conditions of large loads. Second, under the common operating conditions, the system vibrations obtained by the experimental and numerical methods primarily occur at the first fourth-order meshing frequencies and that the maximum vibration amplitude, for each method, appears on the fourth-order meshing frequency. Moreover, root-mean-square (RMS) value of the acceleration increases with the increasing loads. Finally, according to the comparison of the simulation results, the variation tendencies of the RMS value along with input rotational speed agree well and that the frequencies where the resonances occur keep coincident generally. With summaries of merit and demerit, application of each numerical method is suggested for dynamic analysis of cylindrical gear system, which aids designers for desirable dynamic behavior of the system and better solutions to engineering problems.

The Anchor-Last Deployment Problem for Inextensible Mooring Lines

1975 ◽  
Vol 97 (3) ◽  
pp. 1046-1052 ◽  
Author(s):  
Robert C. Rupe ◽  
Robert W. Thresher
Keyword(s):  
Numerical Model ◽  
Equations Of Motion ◽  
Simultaneous Equations ◽  
Mooring Line ◽  
Integration Scheme ◽  
Lumped Mass ◽  
Mooring Lines ◽  
Concentrated Masses ◽  
Predictor Corrector ◽  
Lagrange’S Method

A lumped mass numerical model was developed which predicts the dynamic response of an inextensible mooring line during anchor-last deployment. The mooring line was modeled as a series of concentrated masses connected by massless inextensible links. A set of angles was used for displacement coordinates, and Lagrange’s Method was used to derive the equations of motion. The resulting formulation exhibited inertia coupling, which, for the predictor-corrector integration scheme used, required the solution of a set of linear simultaneous equations to determine the acceleration of each lumped mass. For the selected cases studied the results show that the maximum tension in the cable during deployment will not exceed twice the weight of the cable and anchor in water.

Modeling and Simulation of Clamp Band Dynamic Envelope in a LV/SC Separation System

2011 ◽  
Vol 141 ◽  
pp. 359-363 ◽  
Author(s):  
Jun Lan Li ◽  
Shao Ze Yan ◽  
Xue Feng Tan
Keyword(s):  
Friction Coefficient ◽  
Modeling And Simulation ◽  
Band System ◽  
Separation Process ◽  
Impact Behavior ◽  
Separation System ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Simulation Results ◽  
Contact Impact

The clamp band system is a typical locked and separated device of the launch vehicle (LV) / the spacecraft (SC), and its release-separation process is one of the important factors that affect the LV/SC separation movement. A nonlinear spring-damper model was employed to describe the contact-impact behavior between the V-segment of the clamp band and the LV/SC interface, and lumped mass method was used to depict the clamp band. By using ADAMS, a dynamic model of the clamp band system was established. The simulation results show that the impulse of the explosive bolts and the stiffness of lateral-restraining springs have significant effects on the clamp band dynamic envelope. The shock of the satellite-vehicle separation is very vulnerable to the clamp band pretension and the friction coefficient between the V-segment and the LV/SC interface.

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