• 제목, 요약, 키워드: Energy Absorption

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Energy absorption of the ring stiffened tubes and the application in blast wall design

  • Liao, JinJing;Ma, Guowei
    • Structural Engineering and Mechanics
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    • v.66 no.6
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    • pp.713-727
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    • 2018
  • Thin-walled mental tubes under lateral crushing are desirable and reliable energy absorbers against impact or blast loads. However, the early formations of plastic hinges in the thin cylindrical wall limit the energy absorption performance. This study investigates the energy absorption performance of a simple, light and efficient energy absorber called the ring stiffened tube. Due to the increase of section modulus of tube wall and the restraining effect of the T-stiffener flange, key energy absorption parameters (peak crushing force, energy absorption and specific energy absorption) have been significantly improved against the empty tube. Its potential application in the offshore blast wall design has also been investigated. It is proposed to replace the blast wall endplates at the supports with the energy absorption devices that are made up of the ring stiffened tubes and springs. An analytical model based on beam vibration theory and virtual work theory, in which the boundary conditions at each support are simplified as a translational spring and a rotational spring, has been developed to evaluate the blast mitigation effect of the proposed design scheme. Finite element method has been applied to validate the analytical model. Comparisons of key design criterions such as panel deflection and energy absorption against the traditional design demonstrate the effectiveness of the proposed design in blast alleviation.

Nonuniformity of Energy Absorption Capabilities of ZnO Varistors

  • He, Jin-Liang;Han, Se-Won;Cho, Han-Goo;Kang, Hyung-Boo
    • The Korean Journal of Ceramics
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    • v.4 no.1
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    • pp.47-52
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    • 1998
  • The nonuniformity of energy absorption capability of ZnO varistor is systematically discussed in this paper. The nonuniformity of electrical characteristics and microstructure leads to decrease the energy absorption capability of ZnO varistor. The energy absorption capabilities were measured under different current waves, the experimental results stated that they have highly scattered phenomena. The influences of varistor surface area and nonuniformity of electrical characteristics to the energy absorption capability and the nonuniformity of commercial ZnO varistors were analyzed. There is a high nonuniformity existing in the energy absorption capability of commercial ZnO varistors.

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Energy Absorbing Control Characteristic of Al Thin-walled Tubes (AL 박육부재의 에너지 흡수 제어특성)

  • Yang, Yong-Jun;Yang, In-Young
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.1
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    • pp.86-91
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    • 2008
  • The structural members must be designed to control characteristics of energy absorption for protecting passengers in a car accident. Study on collapse characteristics of structural member is currently conducted in parallel with other studies on effective energy absorption capacity of structural members with diverse cross-sectional shapes and various materials. This study concerns the crashworthiness of the widely used vehicle structural members, square thin-walled tubes, which are excellent in the point of the energy absorption capacity. The absorbed energy, mean collapse load and deformation mode were analyzed for side member which absorbs most of the collision energy. To predict and control the energy absorption, controller is designed in consideration of its influence on height, thickness and width ration in this study. The absorbed energy and mean collapse load of square tubes were increased by $15{\sim}20%$ in using the controller, and energy absorbing capability of the specimen was slightly changed by change of the high controller's height.

Estimation of Neutron Absorption Ratio of Energy Dependent Function for $^{157}Gd$ in Energy Region from 0.003 to 100 eV by MCNP-4B Code

  • Lee, Sam-Yol
    • Journal of the Korean Society of Radiology
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    • v.3 no.3
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    • pp.23-25
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    • 2009
  • Gd-157 material has very large neutron capture cross section in the thermal region. So it is very useful to shield material for thermal neutrons. Futhermore, in the neutron capture experiment and calculation, the neutron absorption and scattering are very important. Especially these effects are conspicuous in the resonance energy region and below the thermal energy region. In the case of very narrow resonance, the effect of scattering is to be more considerable factor. In the present study, we obtained energy dependent neutron absorption ratios of natural indium in energy region from 0.003 to 100 keV by MCNP-4B Code. The coefficients for neutron absorption was calculated for circular type and 1 mm thickness. In the lower energy region, neutron absorption is larger than higher region, because of large capture cross section (1/v). Furthermore it seems very different neutron absorption in the large resonance energy region. These results are very useful to decide the thickness of sample and shielding materials.

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Estimation of Plastic Energy Dissipation Amount of Multi-bent Spatial structure by Equivalent Linear Analysis

  • Lee, Seung-Jae
    • Journal of the Korean Association for Spatial Structures
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    • v.6 no.2
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    • pp.131-136
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    • 2006
  • It is important to evaluate energy absorption capacity of frames required during a design earthquake. An inelastic computer analysis based on mathematical modelling of energy absorbing frames and elements makes it possible to evaluate required energy absorption capacity. But such an analysis sometimes consumes much computation time particularly in case of complicated structural system. This paper presents a proposal to predict energy absorption of multi-bent steel frames by simple equivalent linear method.

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Compression Characteristics and Energy Absorption of Composite Egg-Box Panels (직물 복합재료 계란판의 압축 특성과 에너지 흡수율)

  • Chung, Jee-Gyu;Chang, Seung-Hwan
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.12
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    • pp.1603-1610
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    • 2006
  • In this paper compressive characteristics of composite egg-box panels were investigated and energy absorption was calculated from the nominal stress-strain relations obtained by the compressive tests. Several different stacking sequences and number of plies were introduced for investigation of static compression characteristics and the energy absorption rates of composite egg-box panels. The compressive stress-strain relation and energy absorption of various composite egg-box panels were compared with those of aluminium egg-box panels. From the test results it was found that the fracture behavior of composite egg-box panel was affected by stacking angle causing different local deformation, during lay-up and draping processes and types of prepreg; that is, plain weave carbon/epoxy and 4-harness satin glass/epoxy. The energy absorption capacity of composite egg-box panels were proved to be higher than that of aluminium egg-box panels with low mass.

Energy Absorption Characteristics of Al/CFRP Compound Tubes Under Axial Compression (축 하중을 받는 AI/CFRP 혼성튜브의 에너지흡수 특성)

  • 이길성;차천석;문지현;양인영
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.108-113
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    • 2004
  • The compressive axial collapse tests were performed to investigate energy absorption characteristics of Al/CFRP compound tubes which are aluminum tubes wrapped with CFRP (Carbon Fiber Reinforced Plastics) outside the aluminum circular and square tubes. Based on collapse characteristics of aluminum tubes and CFRP tubes respectively, the axial collapse tests were performed for Al/CFRP compound tubes which have different fiber orientation angles. Test results showed that Al/CFRP compound tubes supplemented the unstable brittle failure of CFRP tubes due to ductile nature of inner aluminum tubes. In the light-weight aspect, specific energy absorption were the highest for Al/CFRP, CFRP in the middle, and aluminum the lowest. Also, specific energy absorption of circular tubes was higher than square tubes'. It turned out that fiber orientation angle of Al/CFRP compound tubes influence specific energy absorption together with the collapse modes of the tubes.

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Calculation of Energy Dependent Neutron Correction Coefficient Ratios of Natural Rhodium in Energy Region from 0.003 to 100 eV

  • Lee, Sam-Yol
    • Journal of the Korean Society of Radiology
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    • v.2 no.3
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    • pp.33-35
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    • 2008
  • In the neutron capture experiment and calculation, the neutron absorption and scattering are very important. Especially these effects are conspicuous in the resonance energy region and below the thermal energy region. In the present study, we obtained energy dependent neutron absorption ratios of natural rhodium in energy region from 0.003 to 100 eV by MCNP-4B Code. The coefficients for neutron absorption was calculated for several types of thickness. In the lower energy region, neutron absorption is larger than higher region, because of large capture cross section (1/v). Furthermore it seems very different neutron absorption in the large resonance energy region. These results are very useful to decide the thickness of sample and shielding materials.

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Energy absorption characteristics of diamond core columns under axial crushing loads

  • Azad, Nader Vahdat;Ebrahimi, Saeed
    • Steel and Composite Structures
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    • v.21 no.3
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    • pp.605-628
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    • 2016
  • The energy absorption characteristics of diamond core sandwich cylindrical columns under axial crushing process depend greatly on the amount of material which participates in the plastic deformation. Both the single-objective and multi-objective optimizations are performed for columns under axial crushing load with core thickness and helix pitch of the honeycomb core as design variables. Models are optimized by multi-objective particle swarm optimization (MOPSO) algorithm to achieve maximum specific energy absorption (SEA) capacity and minimum peak crushing force (PCF). Results show that optimization improves the energy absorption characteristics with constrained and unconstrained peak crashing load. Also, it is concluded that the aluminum tube has a better energy absorption capability rather than steel tube at a certain peak crushing force. The results justify that the interaction effects between the honeycomb and column walls greatly improve the energy absorption efficiency. A ranking technique for order preference (TOPSIS) is then used to sort the non-dominated solutions by the preference of decision makers. That is, a multi-criteria decision which consists of MOPSO and TOPSIS is presented to find out a compromise solution for decision makers. Furthermore, local and global sensitivity analyses are performed to assess the effect of design variable values on the SEA and PCF functions in design domain. Based on the sensitivity analysis results, it is concluded that for both models, the helix pitch of the honeycomb core has greater effect on the sensitivity of SEA, while, the core thickness has greater effect on the sensitivity of PCF.

A Study on the Dynamic Performance of a Solar Absorption Cooling System (태양열 흡수식 냉방 시스템의 동특성 연구)

  • Baek, N.C.;Lee, J.K.;Yang, Y.S.;Jeong, S.
    • Solar Energy
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    • v.18 no.3
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    • pp.81-87
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    • 1998
  • Solar energy has been experiencing renewed interest because of the recent economical crisis in Korea. Absorption cooling is one of the promising solar energy utilization technologies. In this study the dynamic performance of a solar driven absorption cooling machine(SDACM) was numerically investigated. The simulated machine is a commercially available water/LiBr single effect absorption chillers driven by hot water from solar collectors. The present study has been directed to investigate the dynamic behavior of a solar cooling system including an absorption chiller, solar collector, a hot water storage tank, fan coil units, and the air-conditioned space. The operation of the system was simulated for 9 hours in varying operation conditions. The variation of temperature and concentration in the system components, and that of heat transfer rates in the system were obtained. It was also found that the room temperature was maintained near the desired value by controlling the mass flow rate of hot water.

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