• Title/Summary/Keyword: Energy load calculation

Search Result 240, Processing Time 0.026 seconds

Analysis of the Static Friction Coefficient of Contacting Rough Surfaces in Miniature Systems (거친 면 접촉의 정적 마찰계수 해석)

  • 김태종
    • Tribology and Lubricants
    • /
    • v.19 no.4
    • /
    • pp.230-236
    • /
    • 2003
  • In applications such as MEMS and NEMS devices, the adhesion force and contact load may be of the same order of magnitude and the static friction coefficient can be very large. Such large coefficient may result in unacceptable and possibly catastrophic adhesion, stiction, friction and wear. To obtain the static friction coefficient of contacting real surfaces without the assumption of an empirical coefficient value, numerical simulations of the contact load, tangential force, and adhesion force are preformed. The surfaces in dry contact are statistically modeled by a collection of spherical asperities with Gaussian height distribution. The asperity micro-contact model utilized in calculation (the ZMC model), considers the transition from elastic deformation to fully plastic flow of the contacting asperity. The force approach of the modified DMT model using the Lennard-Jones attractive potential is applied to characterize the intermolecular forces. The effect of the surface topography on the static friction coefficient is investigated for cases rough, intermediate, smooth, and very smooth, respectively. Results of the static friction coefficient versus the external force are presented for a wide range of plasticity index and surface energy, respectively. Compared with those obtained by the GW and CEB models, the ZMC model is more complete in calculating the static friction coefficient of rough surfaces.

Fluid-Oscillation Coupled Analysis for HAWT Rotor Blade (One Degree of Freedom Weak Coupling Analysis with Hinge-Spring Model)

  • Imamura, Hiroshi;Hasegawa, Yutaka;Murata, Junsuke;Chihara, Sho;Takezaki, Daisuke;Kamiya, Naotsugu
    • International Journal of Fluid Machinery and Systems
    • /
    • v.2 no.3
    • /
    • pp.197-205
    • /
    • 2009
  • Since large-scale commercial wind turbine generator systems such as MW-class wind turbines are becoming widely operated, the vibration and distortion of the blade are becoming larger and larger. Therefore the soft structure design instead of the solid-design is one of the important concepts to reduce the structural load and the cost of the wind turbine rotors. The objectives of the study are development of the fluid-structure coupled analysis code and evaluation of soft rotor-blade design to reduce the unsteady structural blade load. In this paper, fluid-structure coupled analysis for the HAWT rotor blade is performed by free wake panel method coupled with hinge-spring blade model for the flapwise blade motion. In the model, the continuous deflection of the rotor blade is represented by flapping angle of the hinge with one degree of freedom. The calculation results are evaluated by comparison with the database of the NREL unsteady aerodynamic experiment. In the analysis the unsteady flapwise moments in yawed inflow conditions are compared for the blades with different flapwise eigen frequencies.

Experimental study on hysteretic properties of SRC columns with high steel ratio

  • Lu, Xilin;Yin, Xiaowei;Jiang, Huanjun
    • Steel and Composite Structures
    • /
    • v.17 no.3
    • /
    • pp.287-303
    • /
    • 2014
  • 8 steel reinforced concrete (SRC) columns with the encased steel ratio of 13.12% and 15.04% respectively were tested under the test axial load ratio of 0.33-0.80 and the low-frequency cyclic lateral loading. The cross sectional area of composite columns was $500mm{\times}500mm$. The mechanical properties, failure modes and deformabilities were studied. All the specimens produced flexure failure subject to combined axial force, bending moment and shear. Force-displacement hysteretic curves, strain curves of encased steels and rebars were obtained. The interaction behavior of encased steel and concrete were verified. The hysteretic curves of columns were plump in shapes. Hysteresis loops were almost coincident under the same levels of lateral loading, and bearing capacities did not change much, which indicated that the columns had good energy-dissipation performance and seismic capacity. Based on the equilibrium equation, the suggested practical calculation method could accurately predict the flexural strength of SRC columns with cross-shaped section encased steel. The obtained M-N curves of SRC columns can be used as references for further studies.

A Study on Optimal Capacity Design of Renewable Combined Power System for Energy Self-Sufficient Island (에너지 자립섬을 위한 신재생복합발전시스템의 최적용량 설계에 관한 연구)

  • Chang, Bong-Chul;Moon, Chae-Joo;Chang, Young-Hak;Park, Tae-Sik;Jeong, Moon-Seon
    • The Journal of the Korea institute of electronic communication sciences
    • /
    • v.10 no.11
    • /
    • pp.1271-1276
    • /
    • 2015
  • The recent trend is that diesel power generation on islands where its prime cost for power generation is high is replaced by new and renewable energy. Therefore, south Jeolla province is progressing the construction project of self-sufficient islands for the areas where power is supplied by depending on diesel generators, which is the project that power is supplied through eco-friendly energy source using sunlight, wind power and energy storage device etc. However, it is difficult to construct new and renewable energy source with the capacity to respond to the load perfectly due to its environmental and geographical conditions regarding capacity design of new and renewable energy. Besides, Microgrid design considering appropriate capacity design of the system components and efficient operation is required through the analysis of climate conditions and load patterns from the design stage for optimal composition of a hybrid system with economic feasibility. Therefore, this study is aimed to conduct a research on optimal combination, capacity calculation and economic feasibility by comprising a hybrid power generation system which will replace 40% of power generation by diesel as new and renewable energy source for Geomun Island where has more than 300 households and requires expansion of the facility among islands located in southwest coast.

Post-buckling and Elasto-plastic Analysis of Shell Structures using the Degenerated Shell Element (변형된 쉘요소를 이용한 판 및 쉘 구조의 후좌굴 및 탄.소성 유한요소해석)

  • 김문영;민병철
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 1995.04a
    • /
    • pp.17-27
    • /
    • 1995
  • For the post-buckling and elasto-plastic analysis of shell structures, the total Lagrangian formulation is presented based upon the degenerated shell element. Geometrically correct formulation is developed by updating the direction of normal vectors in the iteration process and evaluating the total Green-Lagrange stain corresponding U total displacements. In the calculation of the stiffness matrix, the element formulation takes into account the effect of finite rotation increments by retaining second order rotation terms in the incremental displacement field. The selective or reduced integration scheme using the heterosis element is applied in order to overcome both shear locking phenomena and the zero energy mode. The load/displacement incremental scheme is adopted for geometric non-linear F .E. analysis. Based on such methodology, the computer program is developed and numerical examples to demonstrate the accuracy and the effectiveness of the proposed shell element are presented and compared with references's results.

  • PDF

Practical Bifurcation Criteria considering Inductive Power Pad Losses in Wireless Power Transfer Systems

  • Kim, Minkook;Lee, Jae-Woo;Lee, Byoung Kuk
    • Journal of Electrical Engineering and Technology
    • /
    • v.12 no.1
    • /
    • pp.173-181
    • /
    • 2017
  • In this paper, the bifurcation criteria for inductive power transfer (IPT) systems is suggested considering the inductive power pad losses. The bifurcation criteria for series-series (SS) and series-parallel (SP) topologies are derived in terms of the main parameters of the IPT system. For deriving precise criteria, power pad resistance is obtained by copper loss calculation and core loss analysis. Utilizing the suggested criteria, possibility of bifurcation occurrence can be predicted in the design process. In order to verify the proposed criteria, 50 W IPT laboratory prototype is fabricated and the feasibilities of the switching frequency and AC load resistance shift to escape from bifurcation are identified.

A Study on the Mathematical Interpretation o Hydraulic Behaviour in Packing Tower (충전탑에서 수력학적 거동의 수학적 해석 연구)

  • 김석택
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.17 no.1
    • /
    • pp.51-56
    • /
    • 2001
  • This study was carried out to interpret mathematically hydraulic behaviour in packing tower which packed 50 mm plastic Hiflow-ring with a dimension of 300 mm wide and 1,400 mm high. In view of energy saving, the recent packing. 50 mm plastic Higlow-ring was superior to conventional packings because of low pressure drop in high loads. As relative error between numerically predicted and experimentally obtained values was less then 6% in the loading and flooding point, it found that therir results appeared to be adequate. Comparison of hose two values in both dry and wet packing conditions. relative errors amount to 3.96 and 5.6%, respectively. In order to evaluate the operating characteristics of packing, the type, size, and material for packings must be estimated in various system and loads. This study is able to calculated pressure drop, hold-up, gas and liquid loads using mathematical interpretation. For these calculation, the specific constants of each packings must be calculated first all. The method of mathematical interpretation in this study turned out to be superior to the existing methods because of reduced errors at loading and flooding point.

  • PDF

Stiffness and Fatigue Strength Analysis of Fuel Cell Vehicle Body Frame (연료전지차량 차체프레임 강성 및 내구해석)

  • Choi, Bok-Lok;Kang, Sung-Jong
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.19 no.4
    • /
    • pp.47-53
    • /
    • 2011
  • Firstly, FEM model for the body frame of a fuel cell vehicle was built up and design optimization results based on different schemes were exhibited. One scheme was to minimize weight while maintaining the normal mode frequencies and the other was to increase the frequencies without weight change. Next, for a rear frame model, shape parameter study on collapse characteristics such as peak resistance load and absorbed energy was carried out. Also, the stiffness of frame mounting brackets was predicted using inertance calculation and the durability of those mounting brackets for vehicle system loads was evaluated. Finally, for a representative mounting model, the influence on durability due to thickness change was analyzed.

The study for design of the foundation insert of large wind turbine (대형풍력터빈 기초 인서트 설계에 관한 연구)

  • Han, Dong-Young;Choi, Won-Ho;Lee, Seung-Kuh
    • 한국신재생에너지학회:학술대회논문집
    • /
    • 2007.06a
    • /
    • pp.391-394
    • /
    • 2007
  • The foundation insert is a tubular steel section which is embedded into the concrete of the foundation. The tower base section of the wind turbine is mounted on it. It has a top flange (L type) protruding far enough above the concrete to allow bolts to be inserted from underneath. The load is transmitted to the concrete at the base of the section through a T shaped flange. It has many holes for the reinforcements and the cables. The reinforcements of the concrete foundation run through the insert via a series of holes to bind the inner section to the outer section. Holes are provided for the power and communications cabling. The design follows normal European wind turbine practice, based on GL 2003 and Eurocode regulations.

  • PDF

A Study on Optimum Application of Unutilized Energies in the Jeju Environment Facility (제주지역 환경시설지구의 미활용 에너지 최적 활용방안에 관한 연구)

  • Kang, B.C.;Park, Y.C.
    • Journal of Power System Engineering
    • /
    • v.11 no.3
    • /
    • pp.9-15
    • /
    • 2007
  • This paper provides a methodology for the optimization of waste heat usage in Jeju Province. The incineration plant was considered as heat source and the food garbage plant and the youth hostel were selected as heat sink of this study. The distribution of the reusing energy in incineration plant is decide by load analysis and numerical calculation of the operational methodology. The main objective of this study is on the reduction of the fuel costs and reuse of waste heat. As the results, the efficiency of the incineration plant and two heat sink, the food garbage plant and the youth hostel, are improved and economical suggestions are proposed through the optimization analysis.

  • PDF