Response Characteristics of Semisubmersible-Type-Megafloat in Waves and Accuracy of Hydroelastic Response Analysis Program VODAC

2002 ◽  
Author(s):  
Hideyuki Suzuki ◽  
Koichiro Yoshida ◽  
Kazuhiro Iijima ◽  
Kentaro Kobayashi
Keyword(s):  
Dynamic Response ◽  
Elastic Response ◽  
Scale Model ◽  
Design Parameters ◽  
Accurate Estimation ◽  
Response Analysis ◽  
Functional Requirements ◽  
Analysis Program ◽  
Floating Structure ◽  
Response Characteristics

Technical feasibility and practical design method of SSMF, a Semi-Submersible-Type-Megafloat, was studied under research funding from Corporation for Advanced Transport and Technology. A SSMF which serves as a airport for local air transportation of isolated islands was assumed in the research. Typical deck size of the SSMF is 2200m long, 300m wide and 9m deep. In the design of the SSMF, column supported type structure was chosen to satisfy the strength and functional requirements in the environmental condition around Japanese islands in the pacific ocean. The deck structure is supported by 320 columns with draft of 16m. In the design of structural dynamics of the SSMF, a computer code VODAC was adopted to calculate hydro-elastic response. VODAC is an analysis program of hydro-elastic response of Very Large Floating Structure (VLFS) which has been developed in University of Tokyo. This paper presents a series of experiments and calculations carried out to investigate response characteristics of SSMF and to confirm capability and accuracy of VODAC. Basin experiments were carried out using a scale model, which is elastically and dynamically similar to the designed SSMF airport, and the response characteristics were clarified. A simple numerical model was also proposed as a simplified model of dynamic response of VLFS. This model is a simple beam on elastic foundation, but it is shown that basic response characteristics of the structure can be relatively accurately expressed by this model. Design parameters were discussed using this model. Relationships between major design parameters and dynamic response characteristics were clarified. Furthermore it was shown that this model is not just a qualitative model but gives relatively accurate estimation of the response. It is shown that this model gives upper limits of response of real structure and a good safe side estimation.

Wave Response of a Semisubmersible Floating Structure Model With Mechanical Connectors

2008 ◽  
Author(s):  
Yoshiyasu Watanabe ◽  
Koichiro Yoshida
Keyword(s):  
Numerical Analysis ◽  
Response Analysis ◽  
Structure Model ◽  
Analysis Program ◽  
Floating Structure ◽  
Response Characteristics ◽  
Wave Response ◽  
New Type ◽  
Hydroelastic Response ◽  
Two Bodies

It is desired instead of welding to develop a mechanical connector, which may work well to connect two units at the site in spite of circumstances of some extent of relative motions between two units caused by waves. One of the authors proposed a new type of mechanical connector, which is based on an idea of three bodies problem instead of usual mechanical connectors (two bodies problem). In this paper, wave exciting tests of a semisubmersible floating structure model with the proposed mechanical connectors of 1/100 scale and the numerical analysis using hydroelastic response analysis program VODAC are carried out and wave response characteristics of the semisubmersible floating structure model with the mechanical connectors and its feasibility are reported.

Dynamic response analysis of a small-scale model tension leg platform

1992 ◽  
Vol 5 (6) ◽  
pp. 491-513 ◽  
Author(s):  
Ney Roitman ◽  
Ricardo F.M. Andrade ◽  
Ronaldo C. Batista
Keyword(s):  
Dynamic Response ◽  
Scale Model ◽  
Small Scale ◽  
Response Analysis ◽  
Tension Leg Platform ◽  
Dynamic Response Analysis ◽  
Small Scale Model

scholarly journals Dynamic Response Analysis of Underground Double-Line Tunnel under Surface Blasting

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Pei Zhang ◽  
Jianhua Cai ◽  
Feng Zong ◽  
Yanpeng He ◽  
Qiong Wang
Keyword(s):  
Dynamic Response ◽  
Vibration Velocity ◽  
Response Analysis ◽  
Horizontal Distance ◽  
Height Difference ◽  
Double Line ◽  
Response Characteristics ◽  
Variation Range ◽  
Clear Distance ◽  
Dynamic Response Characteristics

Blasting has been widely used for economical and rapid rock excavation in civil and mining engineering. In order to study the influence of relative horizontal distance and relative vertical distance between two tunnels on the dynamical response of the two tunnels, 10 numerical simulation cases are done by LS-DYNA 3D models under surface explosion by controlling the clear distance and height difference of double-line tunnel, and the ALE multimaterial fluid structure coupling algorithm is applied to analyze the dynamic response characteristics of double-line tunnel under different conditions. The numerical results show that the dynamic response characteristics of the tunnel lining are affected by the change of the clear distance and height difference of the tunnel. With the increase of the height difference between adjacent tunnels, the peak value of vibration velocity at the top of the lining on the blast face increases, which is due to the upward elevation of the right tunnel, which is more conducive to the reflection and superposition of stress waves. When the height difference of tunnel is 4–6 m, the vibration velocity and displacement of monitoring point C on the back blasting side will change abruptly, and the variation range of vibration velocity is about 25%, while the variation range of displacement is about 60%.

Effect of Structural Dimensions on Strain Growth of Cylindrical Vessels

2013 ◽  
Author(s):  
Q. Dong ◽  
Y. Gu
Keyword(s):  
Dynamic Response ◽  
Influencing Factor ◽  
Blast Loading ◽  
Elastic Response ◽  
Local Dynamic ◽  
Response Characteristics ◽  
Finite Element Software ◽  
Structural Dimensions ◽  
Internal Blast Loading ◽  
Dynamic Response Characteristics

Strain growth is a phenomenon observed in the elastic response of containment vessels subjected to internal blast loading. The local dynamic response of a containment vessel may become larger in a later stage than its response in the earlier stage. To further study the mechanism of strain growth, the effect of structural dimensions on strain growth of cylindrical vessels subjected to internal blast loading is thoroughly investigated in this paper. The dynamic response characteristics of eight cylindrical shells with different lengths and thicknesses are studied by finite element software LS-DYNA. It is shown that the structural dimension is a dominant influencing factor of strain growth.

Random Dynamic Response Analysis of Asphalt Pavement Based on the Vehicle-Pavement Interaction

2015 ◽  
Vol 744-746 ◽  
pp. 1288-1297 ◽  
Author(s):  
Qian Li ◽  
Jun Qing Liu ◽  
Hong Liu
Keyword(s):  
Dynamic Response ◽  
Dynamic Load ◽  
Asphalt Pavement ◽  
Element Model ◽  
Response Analysis ◽  
Vehicle Speed ◽  
Tire Pressure ◽  
Random Load ◽  
Response Characteristics ◽  
Pavement Roughness

In order to analyze the dynamic response of asphalt pavement under vehicle load, the random characteristic of pavement roughness was considered and the vehicle was simplified into 1/2 model with four freedom degrees when establishing the dynamic load model. Then the sequence of the random dynamic load coefficient was obtained by developing a MATLAB program based on the incremental Newmark-β method. Based on the plane strain assumption, a two-dimensional layered finite element model of asphalt pavement was established by ABAQUS software. Then the dynamic load coefficient was used to modify tire pressure that would be applied on the ABAQUS model. Then dynamic response rule of the model and how it was effected by vehicle speed were studied under random load. The results show that under the condition of random load, dynamic response of the pavement structure exhibiting a fluctuation trend as vehicle speed increases and the dynamic response characteristics of each point is different.

scholarly journals A Simplified Model for Dynamic Response Analysis of Framed Self-Centering Wall Structures under Seismic Excitations

2019 ◽  
Vol 2019 ◽  
pp. 1-14
Author(s):  
Xiaobin Hu ◽  
Chen Lu ◽  
Xiaoqing Zhu
Keyword(s):  
Dynamic Response ◽  
Elastic Stiffness ◽  
Simplified Model ◽  
Design Parameters ◽  
Response Analysis ◽  
Seismic Responses ◽  
Analysis Model ◽  
Seismic Excitations ◽  
Element Analysis ◽  
Dynamic Response Analysis

This paper presents a simplified model for dynamic response analysis of the framed self-centering wall (FSCW) structure under seismic excitations. In the analysis model, the frame is equivalent as a single-degree-of-freedom system and collaborates with the self-centering (SC) wall to resist lateral loads. By way of pushover analysis of a typical FSCW structure, the proposed analysis model is validated by comparing the analysis results with those obtained from the finite element analysis method. Using the analysis model, motion equations of the FSCW structure under seismic excitations are established and solved through numerical simulations. Finally, a comprehensive parametric study is conducted to investigate the effects of a variety of design parameters on seismic responses of the FSCW structure. It shows that improving the yield force or elastic stiffness of the frame can help greatly lessen seismic responses of the FSCW structure in terms of the rotation angle of the SC wall.

Numerical Analysis of Nonstationary Thermal Response Characteristics for a Fluid-Structure Interaction System

1999 ◽  
Vol 121 (3) ◽  
pp. 276-282 ◽  
Author(s):  
T. Muramatsu
Keyword(s):  
Numerical Method ◽  
Thermal Response ◽  
Temperature Fluctuations ◽  
Scale Model ◽  
Response Analysis ◽  
Simulation Code ◽  
Response Characteristics ◽  
Experimental Approaches ◽  
Damping Effects ◽  
Thermal Striping

Nonstationary thermal response analysis for a fundamental sodium experiment simulating thermal striping phenomena was carried out using a quasi-direct numerical thermohydraulics simulation code with a third-order upwind scheme for convection terms and a boundary element method code for thermal response evaluation of structures due to random sodium temperature fluctuations developed at Power Reactor and Nuclear Fuel Development Corporation (PNC). Discussions centered on an applicability of the numerical method for the damping effects of the temperature fluctuations in the course of heat transfer to the inside of structures from the fully turbulent region of sodium flows through the comparisons with the experiment. From these comparisons, it was confirmed that the numerical method has a sufficiently high potential in accuracy to predict the damping effects of the temperature fluctuations related to the thermal striping phenomena. Consequently, it is concluded that the numerical prediction by the method developed in this study can replace conventional experimental approaches using 1:1 or other scale model aiming at the simulation of the thermal striping phenomena in actual liquid metal fast breeder reactor (LMFBR) plants. Furthermore, economical improvements in the FBR plants can be carried out based on the discussions of optimization and rationalization of the structural design using the numerical methods.

scholarly journals Structure Dynamic Response of Amphibious Aircraft Induced by Water-Taxiing

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jihang Lyu ◽  
Rong Yang ◽  
Lingcai Huang
Keyword(s):  
Dynamic Response ◽  
Water Surface ◽  
Aerodynamic Force ◽  
Coupling Effect ◽  
Elastic Response ◽  
Structural Vibration ◽  
Approximation Formula ◽  
Response Analysis ◽  
Single Wave ◽  
Added Water

The significant dynamic response under the combined impact of aerodynamic and hydrodynamic forces could be likely to appear because of the structural flexibility, when taxiing on the water surface for amphibious aircraft. Meanwhile, the modal characteristics of the structure are also affected by the additional motion of water. These require that the influence of the structural elasticity and the coupling effect between water and structure should be considered in dynamic response analysis of water-taxiing. According to the peculiarities of the amphibious aircraft, structural dynamics model is based on the distribution of stiffness and mass, Virtual Mass Theory is utilized to solve the wet modes on the water surface, rational function approximations of unsteady aerodynamic force in time-domain are constructed by the Minimum-State Approximation Formula, and loose coupling method is employed to simulate the hydrodynamic elastic response under the encounter of amphibian with single wave and repeated waves, respectively. Analysis of dynamic characteristics during the water-taxiing of the amphibious aircraft has been achieved in this work. The results show that wet natural frequencies of the aircraft have different degrees of decline compared with the dry frequencies because of the influence of added water on the hull, and the response amplitude of dynamic loads obtained by using the wet modes have some certain extent decrease compared with the dry modes. The dynamic amplitude of different locations changes in different degree relatives to the center of gravity position, which reflects the influence of structural elasticity. Due to the excitation of single wave and repeated waves, the structural vibration amplitude will increase rapidly, but the amplitude shows a certain divergence trend under the action of repeated waves with a given oscillation frequency, which is more severe for structural strength design.

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