Experimental and Theoretical Study on the Prediction of Axial Stiffness of Subsea Power Cables

남웅식,채광수,임영석 한국해양공학회 2022 韓國海洋工學會誌 Vol.36 No.4

Subsea power cables are subjected to various external loads induced by environmental and mechanical factors during manufacturing, shipping, and installation. Therefore, the prediction of the structural strength is essential. In this study, experimental and theoretical analyses were performed to investigate the axial stiffness of subsea power cables. A uniaxial tensile test of a 6.5 m three-core AC inter-array subsea power cable was carried out using a 10 MN hydraulic actuator. In addition, the resultant force was measured as a function of displacement. The theoretical model proposed by Witz and Tan (1992) was used to numerically predict the axial stiffness of the specimen. The Newton–Raphson method was employed to solve the governing equation in the theoretical analysis. A comparison of the experimental and theoretical results for axial stiffness revealed satisfactory agreement. In addition, the predicted axial stiffness was linear notwithstanding the nonlinear geometry of the subsea power cable or the nonlinearity of the governing equation. The feasibility of both experimental and theoretical framework for predicting the axial stiffness of subsea power cables was validated. Nevertheless, the need for further numerical study using the finite element method to validate the framework is acknowledged.

On The Stiffness Prediction of GFRP Pipes Subjected to Transverse Loading

Roham Rafiee,Mohammad Reza Habibagahi 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.11

The main objective of this study is to predict the stiffness of GFRP pipes subjected to compressive transverse loading. An experimental study is performed to measure the stiffness of a composite pipe with a core layer of sand/resin composites. Then, a simple analytical modeling constructed on the basis of solid mechanics is used to estimate the stiffness of the investigated pipe as the back-of-envelope technique widely used by industrial sectors. The simulation of stiffness test is conducted using finite element modeling wherein both large deformation and inelastic behavior of material is taken into account as the sources of nonlinearity. The results reveal that a very good estimation with high level of accuracy can be reached by proper selection of the element and performing nonlinear analysis.

자동차 알루미늄 범퍼의 가변 곡률 압출공정 개발

조영근(Young-June Jo),이상곤(Sang-Kon Lee),김병민(Byung-Min Kim),오개희(Kae Hee Oh),박상우(Sang-Woo Park) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.4

The effectiveness of vehicle parts made through extrusion is in the limelight because of the advantages of high strength stiffness materials can be produced and the number of processes can be drastically reduced. Therefore, the parts should have sufficient stiffness and be lightweight enough to improve fuel efficiency. However, the application of extruded aluminum requires pre-bending technologies that can manufacture the complex designs profiles demanded by vehicle parts. The aim of this research is that the development of the variable curvature extrusion technology that can produce a variety of curvature. In order to produce a variable curvature, the guide transfer speed and transfer time should be controlled properly. The guide transfer speed and transfer time were examined by the theoretical analysis. A model was developed to simulate the deformation behaviors of extrusion and bending process from the symmetric bumper with range of radii from 1863mm to 2163mm. The theoretical analysis and FE analysis were verified through experimental method.

Experimental study on the Influence of Heating Surface Inclination Angle on Heat Transfer and CHF performance for Pool Boiling

Chenglong Wang,Panxiao Li,Dalin Zhang,Wenxi Tian,Suizheng Qiu,G.H. Su,Jian Deng 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1

Pool boiling heat transfer is widely applied in nuclear engineering fields. The influence of heating surface orientation on the pool boiling heat transfer has received extensive attention. In this study, the heating surface with different roughness was adopted to conduct pool boiling experiments at different inclination angles. Based on the boiling curves and bubble images, the effects of inclination angle on the pool boiling heat transfer and critical heat flux were analyzed. When the inclination angle was bigger than 90°, the bubble size increased with the increase of inclination angle. Both the bubble departure frequency and critical heat flux decreased as the inclination angle increased. The existing theoretical models about pool boiling heat transfer and critical heat flux were compared. From the perspective of bubble agitation model and Hot/Dry spot model, the experimental phenomena could be explained reasonably. The enlargement of bubble not only could enhance the agitation of nearby liquid but also would cause the bubble to stay longer on the heating surface. Consequently, the effect of inclination angle on the pool boiling heat transfer was not conspicuous. With the increase of inclination angle, the rewetting of heating surface became much more difficult. It has negative effect on the critical heat flux. This work provides experimental data basis for heat transfer and CHF performance of pool boiling.

Experimental and theoretical analysis of electronic musical structures with smart nanoparticles

Jing Han,Maryam Shokravi,F. Ming 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.91 No.4

Nanotechnology has emerged as a promising avenue for enhancing musical structures. In this study, we analyze the static behavior of laser harp (i.e., electronic musical instrument) reinforced with Zinc Oxide (ZnO) nanoparticles. Leveraging the piezoelectric properties of ZnO nanoparticles, the structure is subjected to an electric field for intelligent control. The electronic musical structure is situated in a foundation with vertical springs and shear modulus constants. We employ the exponential Shear Deformation Beam Theory (ESDBT) to mathematically model the structure. A micro-electro-mechanical model is employed to determine the equivalent properties of the system. By utilizing nonlinear stress-strain relations, energy methods, and Hamilton’s principle, we derive the motion equations. The buckling load of the electronic musical beam is calculated using the Difference Quadrature Method (DQM). The primary objective of this study is to present a mathematical model for electronic musical beams and determining the buckling load of the structure and to investigate the influence of nanotechnology and electric fields on its buckling behavior. The buckling is the case when the structure becomes deforms and unstable. Our findings reveal that the application of negative external voltage to the electronic musical structure increases both the stiffness and the buckling load of the musical system. Furthermore, reinforcing the electronic musical structure with ZnO nanoparticles results in an increased buckling load. Notably, the maximum enhancement in the 28-day compressive and tensile strengths of samples containing zinc oxide nanoparticles compared to the control sample resulting in increases of 18.70% and 3.77%, respectively.

Analysis of the Twice-line-frequency Light Flicker of an LED Lamp Driven by a Single-stage PFC Circuit

Yi Li,Gyung-Seok Han,김희준 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.2

A large twice-line-frequency light flicker is a problem for a light-emitting-diode (LED) lamp drivenby a single-stage power-factor-correction (PFC) circuit. This paper proposes a driving circuit forsolving this problem. Furthermore, possible factors that influence the light flicker of a single-stagePFC driven LED lamp are analyzed. The theoretical analysis results are verified by using bothsimulations and experiments.

Moment-curvature hysteresis model of angle steel frame confined concrete columns

Chong Rong,Wenkai Tian,Qingxuan Shi,Bin Wang,Abid Ali Shah 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.83 No.1

The angle steel frame confined concrete columns (ASFCs) are an emerging form of hybrid columns, which comprise an inner angle steel frame and a concrete column. The inner angle steel frame can provide axial bearing capacity and well confining effect for composite columns. This paper presents the experimental and theoretical studies on the seismic behaviour of ASFCs. The experimental study of the 6 test specimens is presented, based on the previous study of the authors. The theoretical study includes two parts. One part establishes the section analysis model, and it uses to analyze section axial force-momentcurvature. Another part establishes the section moment-curvature hysteresis model. The test and analysis results show that the axial compression ratio and the assembling of steel slabs influence the local buckling of the angle steel. The three factors (axial compression ratio, content of angle steel and confining effect) have important effects on the seismic behaviour of ASFCs. And the theoretical model can provide reasonably accurate predictions and apply in section analysis of ASFCs.

Interfacial mechanical behaviors of RC beams strengthened with FRP

Jiangdong Deng,Airong Liu,Peiyan Huang,Xiaohong Zheng 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.3

FRP-concrete interfacial mechanical properties determine the strengthening effect of RC beams strengthened with FRP. In this paper, the model experiments were carried out with eight specimens to study the failure modes and the strengthening effect of RC beams strengthened with FRP. Then a theoretical model based on interfacial performances was proposed and interfacial mechanical behaviors were studied. Finite element analysis confirmed the theoretical results. The results showed that RC beams strengthened with FRP had three loading stages and that the FRP strengthening effects were mainly exerted in the Stage III after the yielding of steel bars, including the improvement of the bearing capacity, the decreased ultimate deformation due to the sudden failure of FRP and the improvement of stiffness in this stage. The mechanical formulae of the interfacial shear stress and FRP stress were established and the key influence factors included FRP length, interfacial bond-slip parameter, FRP thickness, etc. According to the theoretical analysis and experimental data, the calculation methods of interfacial shear stress at FRP end and FRP strain at midspan were proposed. When FRP bonding length was shorter, interfacial shear stress at FRP end was larger that led to concrete cover peeling failure. When FRP was longer, FRP reached the ultimate strain and the fracture failure of FRP occurred. The theoretical results were well consistent with the experimental data.

Preliminary model and validation of molten carbonate fuel cell kinetics under sulphur poisoning

Audasso, E.,Nam, S.,Arato, E.,Bosio, B. Elsevier Sequoia 2017 Journal of Power Sources Vol. No.

<P><B>Abstract</B></P> <P>MCFC represents an effective technology to deal with CO<SUB>2</SUB> capture and relative applications. If used for these purposes, due to the working conditions and the possible feeding, MCFC must cope with a different number of poisoning gases such as sulphur compounds. In literature, different works deal with the development of kinetic models to describe MCFC performance to help both industrial applications and laboratory simulations. However, in literature attempts to realize a proper model able to consider the effects of poisoning compounds are scarce.</P> <P>The first aim of the present work is to provide a semi-empirical kinetic formulation capable to take into account the effects that sulphur compounds (in particular SO<SUB>2</SUB>) have on the MCFC performance. The second aim is to provide a practical example of how to effectively include the poisoning effects in kinetic models to simulate fuel cells performances. To test the reliability of the proposed approach, the obtained formulation is implemented in the kinetic core of the SIMFC (SIMulation of Fuel Cells) code, an MCFC 3D model realized by the Process Engineering Research Team (PERT) of the University of Genova.</P> <P>Validation is performed through data collected at the Korea Institute of Science and Technology in Seoul.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Experimental investigation of the effect of Sulphur fed at the cathode side of MCFC. </LI> <LI> Set up of an MCFC kinetic formulation which takes account of the presence of SO<SUB>2</SUB>. </LI> <LI> Performance simulation and validation of MCFC single cells poisoned with SO<SUB>2</SUB>. </LI> </UL> </P>

Study on Restoring Force Model of RACFST Frame Infilled with RHB Masonry Wall

Ercong Meng,Yalin Yu,Yan Jiang,Shuoyu Liu,Yisheng Su 한국강구조학회 2022 International Journal of Steel Structures Vol.22 No.2

The establishment of a reasonable restoring force model is the basis for popularizing the application of the structure of recycled aggregate concrete fi lled steel tube (RACFST) frame infi lled with recycled hollow block (RHB) masonry wall. To achieve this goal, 2 specimens of RACFST frames infi lled with RHB masonry walls were designed under cyclic reversed load, and the hysteretic and skeleton curves were obtained. The results show that the hysteretic curves of specimens present plump spindle shape, meaning the structure has good energy dissipation ability. The working stages of specimens can be divided into four stages including integral elastic working stage of fi ller wall and frame, frame elastic working stage, elastic–plastic working stage and failure stage. Based on the parallel model of wall and frame, the calculation model for the inter-story bearing capacity, lateral stiff ness and unloading stiff ness of specimens were put forward respectively. Furthermore, the four polyline restoring force model for the structure was built, and it had good agreement with the experimental hysteretic curves.