The Effect of Bending Stiffness on Hydroelastic Response of VLFS

2014 ◽  
Author(s):  
Wei Wei ◽  
Shixiao Fu ◽  
Fei Guo ◽  
Yuanhua Liang ◽  
Shuhong Chai
Keyword(s):  
Rigid Body ◽  
Traditional Method ◽  
Three Dimensional ◽  
Bending Moment ◽  
Bending Stiffness ◽  
Wave Frequency ◽  
Regular Waves ◽  
Floating Structure ◽  
Hydroelastic Response ◽  
Complex Influence

Owing to the flexibility of ocean structures with large dimension, the hydroelastic theory is more applicable than traditional method of treating the floating structure as a rigid body. To study the factors that influence the hydroelastic responses, a very large floating structure (namely, VLFS) model is chosen to conduct numerical calculations in regular waves with the aid of three dimensional linear hydroelastic code concerning varied bending stiffness and wave frequency. It is found that bending stiffness and wave frequency have a critical but complex influence on relevant hydroelastic results, including generalized displacement, vertical response amplitude and bending moment. More specifically, the effect of bending stiffness on hydroelastic parameters above can be categorized into different phases, and quite different tendencies are observed in each phase.

scholarly journals Hydro-Elastic Analysis of a Floating Bridge in Waves Considering the Effect of the Hydrodynamic Coupling and the Shore Sides

2018 ◽  
Author(s):  
Shi Deng ◽  
Shixiao Fu ◽  
Torgeir Moan ◽  
Wei Wei ◽  
Zhen Gao
Keyword(s):  
Potential Flow ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Bending Moment ◽  
Flow Theory ◽  
Floating Structure ◽  
Potential Flow Theory ◽  
Elastic Beams ◽  
Hydrodynamic Coupling ◽  
Floating Bridge

A new numerical method, which is based on three-dimensional (3D) potential flow theory and finite element method (FEM), is used to predict the wave-induced hydroelastic responses of flexible floating bridges. The floating bridge is discretized into several modules based on the positions of the pontoons which are connected by elastic beams. The motion equations of the entire floating structure are established according to the six degrees of freedom (6DOF) motions of each rigid module coupled with the dynamics of the elastic beams. The hydrodynamics loads on each module are considered as external loads and simultaneously applied. The method is extended to take into account the shore side effect, which is obtained from the 3D potential flow theory and considered as a hydrodynamic boundary condition. The effects of inclination of shore side on the responses of the bending moment, horizontal and vertical displacements of the pontoon and their distribution along the bridge are investigated. The results show that the displacement response increase with an increasing steepness of the shore side.

Calculation of Vertical Bending Moment Acting on an Ultra Large Containership in Large Amplitude Waves

2015 ◽  
Author(s):  
Suresh Rajendran ◽  
Nuno Fonseca ◽  
C. Guedes Soares
Keyword(s):  
Large Amplitude ◽  
Bending Moment ◽  
Regular Waves ◽  
Structural Dynamic ◽  
Strip Theory ◽  
Structural Dynamic Characteristics ◽  
Wetted Surface Area ◽  
The Time Domain ◽  
Hydroelastic Response ◽  
Vertical Bending Moment

The time domain method is further extended here in order to calculate the hydroelastic response of an ultra large containership in regular waves. Based on strip theory, the hydrodynamic and the hydrostatic forces are calculated for the instantaneous wetted surface area. Slamming forces are calculated using a Von Karman approach in which the water pile up during slamming is neglected. Timoshenko beam which takes into account the shear deformation and rotary inertia is used to model the structural dynamic characteristics of the hull. The beam is discretized using the finite element method and the ship vibration is solved using the modal analysis. The method is used to calculate the vertical bending moment acting on an ultra large containership in large amplitude regular waves. The results are compared with the experimental results measured in wave tank.

Service Factor Assessment of a Great Lakes Bulk Carrier Incorporating the Effects of Hydroelasticity

2009 ◽  
Vol 46 (02) ◽  
pp. 116-121
Author(s):  
Spyridon E. Hirdaris ◽  
Norbert Bakkers ◽  
Nigel White ◽  
Pandeli Temarel
Keyword(s):  
Rigid Body ◽  
Great Lakes ◽  
Body Wave ◽  
Three Dimensional ◽  
Bending Moment ◽  
Suez Canal ◽  
Two Dimensional ◽  
Bulk Carrier ◽  
Service Factor

This paper presents a summary of an investigation into the effects of hull flexibility when deriving an equivalent service factor for a single passage of a Great Lakes Bulk Carrier from the Canadian Great Lakes to China. induced bending moment predicted using traditional three-dimensional rigid body hydrodynamic methods is augmented due to the effects of springing and whipping by including allowances based on two-dimensional hydroelasticity predictions across a range of headings and sea states. The analysis results are correlated with full scale measurements that are available for this ship. By combining the long term "rigid body" wave-bending moment with the effects of hydroelasticity, a suitable service factor is derived for a Great Lakes Bulk Carrier traveling from the Canadian Great Lakes to China via the Suez Canal.

scholarly journals Rigid-Body Analysis of a Beveled Shape Structure in Regular Waves Using the Weakly Compressible Smoothed Particle Hydrodynamics (WCSPH) Method

2021 ◽  
Author(s):  
Siti Ayishah Thaminah Hikmatullah Sahib ◽  
Muhammad Zahir Ramli ◽  
Muhammad Afiq Azman ◽  
Muhammad Mazmirul Abd Rahman ◽  
Mohd Fuad Miskon ◽  
...  
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Three Dimensional ◽  
Real Life ◽  
Wave Structure ◽  
Regular Waves ◽  
Floating Structure ◽  
Weakly Compressible ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Wcsph Method

AbstractIn many cases of wave structure interactions, three-dimensional models are used to demonstrate real-life complex environments in large domain scales. In the seakeeping context, predicting the motion responses in the interaction of a long body resembling a ship structure with regular waves is crucial and can be challenging. In this work, regular waves interacting with a rigid floating structure were simulated using the open-source code based on the weakly compressible smoothed particle hydrodynamics (WCSPH) method, and optimal parameters were suggested for different wave environments. Vertical displacements were computed, and their response amplitude operators (RAOs) were found to be in good agreement with experimental, numerical, and analytical results. Discrepancies of numerical and experimental RAOs tended to increase at low wave frequencies, particularly at amidships and near the bow. In addition, the instantaneous wave contours of the surrounding model were examined to reveal the effects of localized waves along the structure and wave dissipation. The results indicated that the motion response from the WCSPH responds well at the highest frequency range (ω > 5.235 rad/s).

Design for Flexible Connector of Multi-Floating Structure

2020 ◽  
Author(s):  
Yuan Hongtao ◽  
Chen Gang ◽  
Zhang Wei ◽  
Yin Yan ◽  
Wang Yuhan ◽  
...  
Keyword(s):  
Structural Model ◽  
Structural Strength ◽  
Bending Moment ◽  
Calculation Model ◽  
Wave Direction ◽  
Regular Waves ◽  
Floating Structure ◽  
Hydrodynamic Calculation ◽  
Design Requirements ◽  
Element Theory

Abstract For the connector between the modules of a regular hexagonal multi-floating structure, it designed a flexible connector based on hinge joints and spin joints, which allowed part of rolling, pitching and torsion between adjacent modules to release bending moment and strain. A 221m multi-floating structure hydrodynamic calculation model was modeled in this paper. Firstly, the connector loads under the regular waves were calculated by ANSYS Aqwa. Secondly, structural model of a flexible connector was built by SolidWorks basing on the finite element theory. It analyzed structural strength of the flexible connectors under different load conditions of a series of wave direction angles by ANSYS Static Structral. Lastly, the results show that the design of the multi-floating structure connectors met the design requirements in different working conditions.

Active Control of a Very Large Floating Beam Structure

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Jia Sheng Yang ◽  
Rui Ping Gao
Keyword(s):  
Control Method ◽  
Direct Method ◽  
Vertical Vibration ◽  
Distributed Parameter ◽  
Bending Rigidity ◽  
Parameter System ◽  
Regular Waves ◽  
Floating Structure ◽  
Boundary Control Method ◽  
Hydroelastic Response

In this paper, a novel boundary control method is investigated to suppress the vertical vibration of a very large floating structure (VLFS) with regular waves. The VLFS can be described as a distributed parameter system with partial differential equation (PDE). The proposed boundary controllers are developed based on Lyapunov's direct method to act on the upstream and downstream ends of the VLFS, respectively. Along with the suitable choice of control parameters, the proposed controllers could stabilize the vertical vibration of the VLFS subjected to regular waves. This study verifies the effectiveness of the proposed control methods to the VLFS. Then, the effects of wave amplitude and bending rigidity on the hydroelastic response of the VLFS are investigated.

scholarly journals Research on Hydroelastic Response of an FMRC Hexagon Enclosed Platform

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1110
Author(s):  
Wei-Qin Liu ◽  
Luo-Nan Xiong ◽  
Guo-Wei Zhang ◽  
Meng Yang ◽  
Wei-Guo Wu ◽  
...  
Keyword(s):  
Time Domain ◽  
Numerical Models ◽  
Structural Response ◽  
Deep Ocean ◽  
Surface Model ◽  
Large Area ◽  
Floating Structure ◽  
Small Depth ◽  
Response Amplitude Operators ◽  
Hydroelastic Response

The numerical hydroelastic method is used to study the structural response of a hexagon enclosed platform (HEP) of flexible module rigid connector (FMRC) structure that can provide life accommodation, ship berthing and marine supply for ships sailing in the deep ocean. Six trapezoidal floating structures constitute the HEP structure so that it is a symmetrical very large floating structure (VLFS). The HEP has the characteristics of large area and small depth, so its hydroelastic response is significant. Therefore, this paper studies the structural responses of a hexagon enclosed platform of FMRC structure in waves by means of a 3D potential-flow hydroelastic method based on modal superposition. Numerical models, including the hydrodynamic model, wet surface model and finite element method (FEM) model, are established, a rigid connection is simulated by many-point-contraction (MPC) and the number of wave cases is determined. The load and structural response of HEP are obtained and analyzed in all wave cases, and frequency-domain hydroelastic calculation and time-domain hydroelastic calculation are carried out. After obtaining a number of response amplitude operators (RAOs) for stress and time-domain stress histories, the mechanism of the HEP structure is compared and analyzed. This study is used to guide engineering design for enclosed-type ocean platforms.

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

Measurement of Angular Acceleration of a Rigid Body Using Linear Accelerometers

1975 ◽  
Vol 42 (3) ◽  
pp. 552-556 ◽  
Author(s):  
A. J. Padgaonkar ◽  
K. W. Krieger ◽  
A. I. King
Keyword(s):  
Experimental Data ◽  
Rigid Body ◽  
Simple Procedure ◽  
Three Dimensional ◽  
Angular Acceleration ◽  
Theory And Practice ◽  
Body Segments ◽  
Impact Biomechanics ◽  
The Stability ◽  
Definition Of

The computation of angular acceleration of a rigid body from measured linear accelerations is a simple procedure, based on well-known kinematic principles. It can be shown that, in theory, a minimum of six linear accelerometers are required for a complete definition of the kinematics of a rigid body. However, recent attempts in impact biomechanics to determine general three-dimensional motion of body segments were unsuccessful when only six accelerometers were used. This paper demonstrates the cause for this inconsistency between theory and practice and specifies the conditions under which the method fails. In addition, an alternate method based on a special nine-accelerometer configuration is proposed. The stability and superiority of this approach are shown by the use of hypothetical as well as experimental data.

Sign in / Sign up

Export Citation Format

Share Document