scholarly journals Sloshing Impact Response in LNG Membrane Carriers: A Response Analysis of the Hull Structure Supporting the Membrane Tanks

2016 ◽  
Author(s):  
Jonas W. Ringsberg ◽  
André Liljegren ◽  
Ola Lindahl
Keyword(s):  
Structural Response ◽  
Response Analysis ◽  
Impact Loads ◽  
Dynamic Amplification Factor ◽  
Insulation System ◽  
Load Duration ◽  
Hull Structure ◽  
Load Characteristics ◽  
Membrane Type ◽  
Dynamic Amplification

This study presents the determination of structural response due to sloshing impact loads in LNG carriers with membrane type cargo tanks. These loads are characterized by very short durations and are thus likely to inflict a dynamic amplification in the response of the hull. Finite element analyses are presented using a model representing parts of an LNG membrane tank. The objective was to find and quantify the dynamic amplification factor (DAF) for the structural response towards sloshing impact pressures. The influence of variations in the load characteristics such as load duration, extent of the loaded area, load location as well as the influence of the insulation system was evaluated. The study shows that the response in the studied region of the hull structure experiences significant levels of dynamic amplification during impact loads with specific durations. The response sensitivity analysis also shows that the insulation system (MARK III type) has a large effect on the dynamic behaviour of the hull structure. It has been found to alter the magnitude of the stress and deflection response for key structural members. It also changes the load time durations for which the maximum dynamic amplification occurs and increases the magnitude of the corresponding response DAF. Finally, it has been found that dynamic response gives DAF values of up to 2. The effects have been found to be present for temporal load characteristics commonly occurring in sloshing model tests and full-scale measurements and are therefore likely to occur for a vessel in operation.

Hull Deformation Effect on Membrane-Type LNG Containment Systems

2016 ◽  
Author(s):  
Bo Wang ◽  
Yung-Sup Shin ◽  
Eric Norris
Keyword(s):  
Structural Integrity ◽  
Water Pressure ◽  
Local Deformation ◽  
Fatigue Tests ◽  
Wave Loads ◽  
Insulation System ◽  
Structural Fatigue ◽  
Hull Structure ◽  
Membrane Type ◽  
Global Deformation

The objective of this study is to investigate the relationship between the maximum allowable hull deformation, which includes global elongation and local deflection, and the capacity of the CCS in membrane-type LNG vessels. The LNG CCS mainly consists of the primary barrier (e.g. a corrugated membrane for GTT MK III system and an invar membrane for GTT NO 96 system) and the insulation panel which is attached to the inner hull through mastics or couplers. The excessive hull elongation due to dynamic wave loads may cause fatigue damage of the primary barrier. Thus, the maximum allowable hull elongation (global deformation) can be determined based on the fatigue strength of the primary barrier. On the other hand, the excessive hull deflection due to cargo or ballast water pressure may cause failure of the insulation panel and the mastic. Therefore, the maximum allowable hull deflection (local deformation) in the hull design can be determined based on the strength of the insulation panel and the mastic. In the present paper, the determination of fatigue life vs. strain curves of materials has been summarized for the primary barrier. Fatigue curves based on either structural fatigue tests or standard specimen tests can be applied in fatigue assessment of a primary barrier. As an example, the finite element (FE) analysis has been conducted on the MK III CCS with the hull structure under pressure loads. Two different load cases including full load and ballast load conditions have been considered to evaluate the structural integrity of the insulation system in numerical simulations. FE results show that the mechanical behavior of the insulation system and the mastic under the maximum allowable hull deflection has been examined based on the yielding strength of each individual component. Finally, the complete procedure to determine the maximum allowable hull elongation and the maximum allowable hull deflection has been developed for meeting the requirements of containment system design for membrane-type LNG carriers.

A Comparative Study on the Impact Damage of Membrane Type LNGC Insulation System

2009 ◽  
Author(s):  
Min Sung Chun ◽  
Yong Suk Seo ◽  
Ito Hisasi ◽  
Wha Soo Kim ◽  
Byeong Jae Noh ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Failure Mode ◽  
Impact Load ◽  
Impact Damage ◽  
Structural Response ◽  
Structural Safety ◽  
Structural Behavior ◽  
Insulation System ◽  
Membrane Type ◽  
The Impact

To verify the structural safety under impact load caused by sloshing of LNG is one of the main issues in the design of membrane type LNG cargo containment system of LNG carrier. In order to estimate structural response under sloshing impact load, many kinds of studies including experimental test and numerical simulation have been done by various research groups such as shipyards, oil companies, universities as well as classification societies. In spite of these efforts, many uncertainties still exist to predict the structural behavior of LNG insulation system under sloshing impact load. Therefore, it can be regarded as a challenge to investigate dynamic response of LNG cargo insulation system against sloshing load. In this paper, Cooperative research results obtained by SHI-HHI-PNU-Lloyd-ABS-DNV JDP focused on the impact damage or failure mode of membrane type LNG cargo insulation system are summarized. A systematic experimental research is carried out to find out failure mode of the insulation system under impact load and criteria which can be applied for the design of LNG carrier. A series of dry drop tests as well as static compressive tests are carried out. The structural behavior of the specimen under impact load is recorded using ultrahigh-speed camera and reaction force is measured using load cells which are installed under bottom of the test facility. By analyzing recorded video, deformation history of the specimen at impact moment is obtained. The numerical simulations are also carried out for the dry drop test for verification purpose, It is expected that the insights observed from the systematic experiments and numerical simulations for the structural response of the LNG cargo insulation system subjected to the impact load can be effectively used as design guide for evaluation of the integrity of structural components of LNG cargo hold system.

Hydroelastic Analysis of the Bending-Torsional Coupling Vibrations of an Ultra-Large Container Ship

2020 ◽  
Author(s):  
Hui Li ◽  
Lin Lu
Keyword(s):  
Resonance Phenomenon ◽  
Response Analysis ◽  
Container Ship ◽  
Hull Structure ◽  
Torsional Coupling ◽  
The Difference ◽  
Dynamic Amplification ◽  
Actual Response ◽  
Large Container ◽  
Wave Induced

Abstract Springing is a resonance phenomenon between the waves and the ship hull, and the high frequency vibration will threaten the safety of hull structures. With the development of economy, the size of ultra large container ships has been increasing, and the resulting springing and whipping response and their effects has been paid more and more attention. The structure of an ultra large container ship is essentially U-shaped with a low shear center, which results in strong coupling between horizontal bending and torsion. On the other hand, the actual response of hull structures will have an apparently dynamic amplification phenomenon under the effect of springing. In this paper, the wave-induced loads on the hull structure is estimated in the framework of the 3D linear hydroelastic theory, which coupling horizontal and torsional vibration. The vibration characteristics are investigated by using finite element method (FEM), which can get a better calculation accuracy than the simplified calculation method such as the Transfer Matrix Method. And the mode shape of displacement and section loads of the whole ship can be obtained and processed, which is needed for the analysis of hydroelasticity. Finally, in order to consider the effect of the dynamic amplification effect, the dynamic response analysis approach is used for the stress calculation. A 21000TEU is calculated by this method, and the difference between wave-induced and springing-induced section load in frequency domain is shown. Then the results of the frequency response analysis is compared with the quasi-static methods. And the effect of the springing and the dynamic magnification is analyzed.

Global Structural Response Analysis of Jack-Up Ship in Transit Condition

2013 ◽  
Vol 344 ◽  
pp. 66-69
Author(s):  
Xiang Zhu ◽  
Yong Sheng Tang ◽  
Yao Zhao ◽  
Heng Kui Ye
Keyword(s):  
Structural Response ◽  
Bending Moment ◽  
Element Model ◽  
Inertia Force ◽  
Response Analysis ◽  
Wave Loads ◽  
Critical Areas ◽  
Hull Structure ◽  
In Transit ◽  
Jack Up

The global structural response of a four-leg jack-up wind turbine installation ship in the transit condition was analyzed in this paper. The finite element model of the hull and legs were established with the Software MSC. PATRAN. On the basis of long-term forecast of the wave loads, the corresponding designed wave parameters are determined with the vertical wave bending moment of the midship cross section served as the main load control parameter. Considering the gravity, hydrostatic pressure, the hydrodynamic loads induced by the wave, inertia force induced by the motion and acceleration of the ship and the wind force on the legs and hull, the direct calculated method was used to evaluate the global structural response of the vessel. The deformation and stress of the hull and legs were calculated and checked. The results showed that the strength of the hull and leg could meet the rules requirements. For the jack-up ship in the transit condition, the critical areas are mainly lower part of legs and the corresponding hull structure.

scholarly journals El Paisaje Arquitectónico y sonoro del Campanario de la Catedral de San José de Cúcuta. [The Architectural and Sound Landscape of the Bell Tower of the Cathedral of San José de Cúcuta]

2019 ◽  
Vol 11 (1) ◽  
pp. 52-60
Author(s):  
Julio Alfredo Delgado ◽  
Yanette Díaz Umaña, Vergel, M
Keyword(s):  
Numerical Model ◽  
Landscape Architecture ◽  
Amplification Factor ◽  
Methodological Approach ◽  
Structural Response ◽  
San Jose ◽  
Dynamic Amplification Factor ◽  
Historical Method ◽  
Bell Tower ◽  
Dynamic Amplification

Este artículo tuvo como objetivo analizar las particularidades de las cuatro campanas y la torre, que compone el campanario de la Catedral de San José de Cúcuta, así como también su impacto en el paisaje sonoro de esta ciudad del Norte de Santander en Colombia. La investigación tuvo un enfoque metodológico mixto, en el que se incluyen el método descriptivo e histórico. Se recurrió, además, a un modelo numérico simplificado de la estructura, determinando el espectro de respuesta estructural. Según las campanas se analizó, magnitudes de la función de fuerzas variables con el tiempo que introducen sobre la estructura el peso propio, velocidad de giro e inercia; se determina el factor de amplificación dinámico más desfavorable y respuesta para análisis cuasi estático para las fuerzas. Se concluye que el toque de las campanas produce un sonido patrimonial único que posee cualidades que lo hacen identificable por la comunidad. De tal manera, que las disposiciones de las campanas tienen efectos en la estructura del campanario y en el sonido, por consiguiente, la campana de mayor peso introduce mayores esfuerzos en la torre con factor incidente directo la ubicación en el campanario.Palabras clave: Campanas, Paisaje, Arquitectura, sonido, fuerzas, variables.AbstractThis article aimed to analyze the particularities of the four bells and the tower, which comprises the bell tower of the Cathedral of San José de Cúcuta, as well as its impact on the sound landscape of this city of Norte de Santander in Colombia. The research had a mixed methodological approach, which includes the descriptive and historical method. We also resorted to a simplified numerical model of the structure, determining the spectrum of structural response. According to the bells, we analyzed the magnitudes of the function of variable forces with time that introduce the own weight, speed of rotation and inertia on the structure; the most unfavorable dynamic amplification factor and response for quasi-static analysis for forces is determined. It is concluded that the ringing of bells produces a unique patrimonial sound that possesses qualities that make it identifiable by the community. In such a way, that the provisions of the bells have effects on the structure of the bell tower and on the sound, consequently, the bell of greater weight introduces greater efforts in the tower with direct incident factor the location in the bell tower.Keywords: Bells, Landscape, Architecture, sound, forces, variables.ResumoEsta pesquisa teve como objetivo analisar as particularidades dos quatro sinos e da torre, que compreende a torre sineira da Catedral de San José de Cúcuta, bem como seu impacto sobre a paisagem sonora desta cidade de Norte de Santander, na Colômbia. A pesquisa teve uma abordagem metodológica mista, que inclui o método descritivo e histórico. Recorremos também a um modelo numérico simplificado da estrutura, determinando o espectro da resposta estrutural. De acordo com os sinos, analisamos as magnitudes da função das forças variáveis com o tempo que introduzem o próprio peso, velocidade de rotação e inércia na estrutura; o fator de amplificação dinâmica mais desfavorável e a resposta para a análise quase-estática de forças é determinada. Conclui-se que o toque dos sinos produz um som patrimonial único que possui qualidades que o tornam identificável pela comunidade. De tal maneira, que as provisões dos sinos tenham efeitos sobre a estrutura da torre do sino e no som, consequentemente, o sino de maior peso introduz maiores esforços na torre com fator incidente direto a localização na torre do sino.Palavras-chave: Sinos, Paisagem, Arquitetura, som, forças, variáveis.

scholarly journals Temperature Distribution in the Insulation System of Condenser-Type HV Bushing—Its Effect on Dielectric Response in the Frequency Domain

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 4016
Author(s):  
Krzysztof Walczak ◽  
Jaroslaw Gielniak
Keyword(s):  
Temperature Distribution ◽  
Working Conditions ◽  
Dielectric Response ◽  
Power Transformers ◽  
Response Analysis ◽  
Insulation System ◽  
Large Power ◽  
Catastrophic Failures ◽  
Significant Temperature ◽  
Specific Construction

HV bushings are an important part of the equipment of large power transformers, responsible for their many serious (including catastrophic) failures. Their proper exploitation needs to apply correct and reliable diagnostics, e.g., the use of dielectric response methods, that take into account their specific construction and working conditions. In this article, based on laboratory tests carried out on a real bushing, it has been shown that the significant temperature distribution within its core significantly affects the shape of the dielectric response of its insulation; therefore, the approach to its modeling should be changed. Hence, a new method for interpreting the results, using the so-called the 2XY model, is proposed. Subsequently, based on the measurements made on the insulators in operation, a new modeling method was verified. In conclusion, it can be stated that the 2XY model significantly improves the reliability of the dielectric response analysis, which should be confirmed in the future by tests on withdrawn and revised insulators.

Dynamic Response Analysis of Butt Joint of HTS-A Steel Considering Welding Residual Stresses

2013 ◽  
Vol 423-426 ◽  
pp. 944-950
Author(s):  
Wei Shen ◽  
Ren Jun Yan ◽  
Lin Xu ◽  
Kai Qin ◽  
Xin Yu Zhang ◽  
...  
Keyword(s):  
Residual Stress ◽  
Dynamic Response ◽  
Hot Spot ◽  
Time History ◽  
High Strength ◽  
Simulation Method ◽  
Butt Joint ◽  
Welding Residual Stress ◽  
Response Analysis ◽  
Hull Structure

This paper uses both numerical simulation method and experimental research method to study on welding residual stress of high-strength steel of the cone-cylinder hull. Welding is often accompanied by a larger welding residual stress, which directly affects the safety and service life of the hull structure. In order to obtain the distribution of the welding residual stress, the welding procedure was developed by its parameter language by using FE analysis software in this paper. Then the welding residual stress of hot spot region was measured through X-ray nondestructive testing method, and compared it with simulation results. Finally, considering the residual stress as the initial stress, this paper analyzed dynamic response process of the welding structure under combined actions of the welding residual stress and multiaxial loads, which could more accurately determine the stress of welding structure and the location of fatigue risk point. According to the amplitude of damage parameters and strain time-history curve, we can estimate the fatigue life of structure by selecting the corresponding damage models.

Analysis of test blanket module attachments under electromagnetic loads by using a dynamic amplification factor envelope

2018 ◽  
Vol 136 ◽  
pp. 1247-1251
Author(s):  
Raúl Muñoz ◽  
Francisco J. Calvo ◽  
Sergio Sádaba ◽  
Ana M. Gil ◽  
Javier Rodríguez ◽  
...  
Keyword(s):  
Amplification Factor ◽  
Dynamic Amplification Factor ◽  
Dynamic Amplification

Dynamic Response of a Generic Vehicle Floor Model to Coupled Transient Loads

1996 ◽  
Author(s):  
Aaron D. Gupta
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Response Analysis ◽  
Impact Loads ◽  
Valuable Insight ◽  
Concentrated Load ◽  
Shell Elements ◽  
Transient Loads ◽  
Method Of Evaluation ◽  
The Impact

Abstract A dynamic elastic large displacement response analysis of the bottom floor of a generic vehicle hull model subjected to empirically obtained coupled blast and impact loads has been conducted using three-dimensional (3-D) shell elements in the ADINA nonlinear dynamic finite element analysis code. For the impulse-dominated problem, the impact load is a square wave step function concentrated load while the blast loads from the detonation of an explosive are a series of distributed pressure loads approximated as triangular impulse loads with linear decay and varying arrival and duration times. The 3-D numerical model has been generated using the PATRAN3 modeling code and converted to the ADINA finite element input data deck using the ADINA translator and careful inclusion of appropriate material properties as well as initial and boundary conditions. Monolithic single-layered four-noded quad shell elements were sufficient to model the bottom floor and the left- and right-horizontal and vertical sponsons as well as the lower front glacis. Although several simplifying assumptions and approximations are made during the generation of the basic floor model, material properties, and the forcing functions, the investigation gives valuable insight into the response behavior of a generic hull bottom floor to externally applied coupled blast and impact loads and provides an inexpensive nondestructive method of evaluation of the structural integrity of modern vehicles subjected to spatially varying transient loads.

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