• Title/Summary/Keyword: shear ring

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The effects of Welding Conditions on Tensile Properties of Friction Stir Lap Welded of Dissimilar Al Alloy, A6K31/A5J32 (이종 알루미늄 합금 A6K31/A5J32 겹치기 마찰교반 접합부의 인장성질에 미치는 접합조건의 영향)

  • Yoon, Tae-Jin;Kim, Sang-Ju;Song, Sang-Woo;Hong, Jae-Keun;Kang, Chung-Yun
    • Journal of Welding and Joining
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    • v.29 no.2
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    • pp.72-79
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    • 2011
  • The scope of this investigation is to evaluate the effect of joining parameters on the microstructural features and mechanical properties of dissimilar aluminum alloys, 1mm-thickness fixing AA6K31 at the top position and fixing AA5J32 at the bottom position. The friction stir lap welds were studied under various welding conditions, rotation speed of 1000, 1250, 1500rpm and welding speed of 100, 300, 500, 700mm/min, respectively. Mechanical test has been investigated in terms of tensile shear test and hardness test. The results showed that three type nugget shapes such as onion ring, zigzag type, hooking with the void, have been observed with revolutionary pitch. All welding conditions fractured at the HAZ of top plate, A6K31 and also the strength compare with base metal of lap joints were low efficiency, 52~63%. The thickness of fractured position was decreased with the lower heat input conditions. The relationships were excellent due to linear between the effective thickness of fractured position and peak load. The fractured position was the interface between joint area and not joint area. Also the strength efficiency compared with base metal was lower than decreasing rate of thickness because the hardness was decreased at fractured position due to softened material.

Magnetic Circuit Design Methodology of MR CDC Dampers for Semi-Active Suspensions (반능동 서스펜션용 MR CDC 댐퍼의 자기회로 설계기법)

  • Park, Jae-Woo;Jung, Young-Dae
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.10
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    • pp.48-57
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    • 2008
  • MR Fluid, one of functional fluids, is developed for the application to automobile products. MR CDC damper using MR fluid has following principles. When ar electric current is applied to the solenoid, apparent viscosity of MR fluid passing through the annular gap which acts as magnetic circuits varies directly as the intensity of the current. These devices have a simple structure and excellent lime response characteristics, emerging as the alternatives of the conventional semi-active suspension systems. In this study, a design procedure of the magnetic circuit through the solenoid fore and the flux ring functioning as a magnetic path is investigated so as to optimize the design and performance of MR CDC dampers for the vehicles. In addition, an operating point on the B-H curve, the magnetization according to the variation in the annular gap, the pole piece width and the density of MR fluid are studied to design the optimal piston head within the restrained dimension range.

Numerical Analysis on the Effect of Flow Rate Variation in Double-Suction Centrifugal Pump (양흡입 원심펌프에 있어서 유량변화의 영향에 관한 수치해석적 연구)

  • An, Young-Joon;Shin, Byeong-Rog
    • The KSFM Journal of Fluid Machinery
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    • v.13 no.6
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    • pp.51-56
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    • 2010
  • A numerical simulation is carried out to investigate the effect of flow rate variation and performance characteristics of double-suction centrifugal pump. Two types of pump which have different impeller inlet breadth and curvature of the shroud line consist of six blades impeller and shroud ring. Finite-volume method with structured mesh and $k-\omega$ Shear Stress Transport turbulence model was used to guaranty more accurate prediction of turbulent flow in the pump impeller. Total head, power and overall efficiency were calculated to obtain performance characteristics of two types of pump according to the variation of flow rate. From the results, impeller having smooth curve along the shroud line obtained good performance. The lower flow rate, the more circulation region, flow unsteadiness and complicate flow pattern are observed. Complicated internal flow phenomena through impellers such as flow separation, pressure loss, flow unsteadiness and performance are investigated and discussed.

Model Test on the Three-Slot Cambered Otter Board with Accessories (부속구를 부착한 슬롯 만곡형전개판의 성능에 관한 모형실험)

  • Gwon, Byeong-Guk;Go, Gwan-Seo
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.30 no.2
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    • pp.71-77
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    • 1994
  • A serious of study is carried out to practical use of the three-slot cambered otter board improved by the authors. As the first step, we designed main plates, slots and accessories, such as holding plate, fan-shaped towing plate, normans, center ring, etc. Standing on this design, we made the simple cambered and three-slot cambered model otter board with accessories in a linear scale 6:1. and carried out model test to examine the efficiency of these boards. The obtained results can be summarized as follows: 1. On the simple cambered board with accessories, the values of the maximum shear coefficient($C _{LX}$ ). drag coefficient(($C _{D}$) and hydrodynamic efficiency($C _{L}$/$C _{D}$ ) are 1.39, 0.56, 2.48 at $22^{\circ}$ of the angle of stall respectively. 2. On the three-slot cambered board with accessories, $C _{LX}$/$C _{D}$ and $C _{I}$/$C _{D}$ are 1.67, 0.92, 1.82 at $32^{\circ}$ of the angle of stall respectively. 3.$C _{LX}$ of board with accessories is smaller 10~12% than that of only the main plate, and the angle of stall is almost same. 4. $C _{LX}$ and the angle of stall of the three-slot cambered board with accessories are greater 20% and $10^{\circ}$ than that of the simple cambered board respectively.

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Study on the Manufacturing Technology of 2-Cavity Fine Blanking Seat Recliner Die with Minute Module of Accurate Gear (초정밀 Gear 미세 모듀율을 가진 2 Cavity 파인 블랭킹 시트 리클라이너 금형 제조기술에 관한 연구)

  • Park, Dong-Hwan;Kwon, Hyuk-Hong
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.2
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    • pp.22-30
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    • 2016
  • It is very important to obtain the net shape of the product to maximize the shear cutting surface of fine blanking. In this paper, the fine blanking die was manufactured to achieve part characteristics, such as flatness and a fully sheared surface. The V-ring in the fine blanking die was designed to prevent lateral movement of the material. The fine blanking experiment was conducted with the fine blanking die. The material usage rate was increased by over 5.7% and that of the water-soluble lubricant was decreased by over 33% when the 2-cavity die technology was applied to fine blanking. The capacity of the existing press could lead to productivity improvement and cost reduction. Thus, 2-cavity die technology for fine blanking with a minute module of an accurate gear for producing seat recliner parts was developed.

Evaluating the performance of OBS-C-O in steel frames under monotonic load

  • Bazzaz, Mohammad;Andalib, Zahra;Kafi, Mohammad Ali;Kheyroddin, Ali
    • Earthquakes and Structures
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    • v.8 no.3
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    • pp.699-712
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    • 2015
  • Bracing structures with off-centre bracing system is one of the new resistant systems that frequently used in the frame with pin connections. High ductility, high-energy dissipation and decrease of base shear are advantages of this bracing system. However, beside these advantages, reconstruction and hard repair of off-centre bracing system cause inappropriate performance in the earthquake. Therefore, in this paper, the goal is investigating the behavior of this type of bracing system with ductile element (circular dissipater), in order to providing replacement of damaged member without needing repair or reconstruction of the general system. To achieve this purpose, some numerical studies have been performed using ANSYS software, a frame with off-centre bracing system and optimum eccentricity (OBS-C-O) and another frame with the same identifications without ductile element (OBS) has been created. In order to investigate precisely on the optimum placement of circular elements under monotonic load again three steal frames were modeled. Furthermore, the behavior of this general system investigated for the first time, linear and nonlinear behavior of these two steel frames compared to each other, to achieve the benefit of using the circular element in an off-centre bracing system. Eventually, the analytical results revealed that the performance of steel ring at the end of off-centre braces system illustrating as a first defensive line and buckling fuse in the off-centre bracing system.

Fabric Weavability and Machine Efficiency in the Various Weaving Machines such as Projectile, Rapiers, and Air-jet (프로젝타일, 래피어 그리고 에어젯트 직기의 제직성과 직기효율)

  • Kim, S.J.;Yeo, G.D.
    • Textile Coloration and Finishing
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    • v.12 no.1
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    • pp.1-11
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    • 2000
  • This paper surveys the fabric weavability and machine efficiency in the various weaving looms such as Projectile, Rapiers, and Air-jet. Used projectile loom was Sulzer-PU, and FAST-R, THEMA-11E, and Picanol-GTX were used for Rapier looms, as the Air-Jet looms, Picanol PAT and OMNI types were used. Using these looms, 5 harness worsted satin fabrics were woven for surveying the fabric weavability and machine efficiency. Warp yam count of fabric is 1/40Nm, Sirofil, and filling is 1/30 Nm, worsted. End breaks of warp and filling directions for the various types of looms are measured and discussed with the mechanism of each loom. Warp and filling yam tensions are also measured and analysed with open width of shedding motion of each weaving machine. And various warp yam tensions with open width of shedding are measured and analysed according to the warp yam in various heald frame. These results fire also discussed with temples such as bar and ring. Warp yam tensions at the various positions on the fabric with various looms are measured and discussed with fabric mechanical properties such as tensile, bending, shear and surface.

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Giant Molecular Cloud Properties of WISDOM galaxies - NGC 5806 and NGC 6753

  • Choi, Woorak;Liu, Lijie;Bureau, Martin;Davis, Timothy;Chung, Aeree
    • The Bulletin of The Korean Astronomical Society
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    • v.46 no.1
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    • pp.56.2-56.2
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    • 2021
  • Constraining the structure and thus the fate of giant molecular clouds (GMCs), the primary sites of star formation in galaxies, is crucial to understand the evolution of galaxies themselves. Exploiting the unprecedented sensitivity and angular resolution of the Atacama Large Millimeter/sub-millimeter Array (ALMA), we have measured the spatially-resolved (~ 20 pc resolution) properties of the GMCs in two nearby late-type galaxies, NGC 5806 (SAB(s)b) and NGC 6753 ((R)SA(r)b), as part of the WISDOM project. Although these results are preliminary, we identified ~ 200 resolved GMCs in NGC 5806 within a radius of 500 pc, most within a nuclear ring structure, and ~ 400 resolved GMCs in NGC 6753 within a radius of 2 kpc, most within a flocculent spiral structure. The GMCs of NGC 5806 have similar sizes but slightly higher linewidths than clouds in the Milky Way disc. Because the GMCs also have higher surface densities, the calculated cloud Virial parameters are nevertheless about unity, suggesting that the GMCs of NGC 5806 are in gravitational equilibrium and thus long lived. This is contrary to other WISDOM results on earlier-type galaxies, where large cloud linewidths are likely due to shear associated with the local (circular) orbital motions (rather than the clouds' self-gravity), and the clouds are either marginally or not gravitationally bound. These results support the notion that spheroids alter the dynamical states of clouds (morphological quenching), that are otherwise (i.e. in galaxy discs) fairly homogenous and similar to those of the Milky Way.

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A Study on the Water Resistance and Thermo-mechanical Behaviors of Epoxy Adhesives (에폭시 접착제의 내수성, 열적 및 기계적 물성에 관한 연구)

  • Park, Soo-Jin;Kim, Jong-Hak;Choi, Kil-Yeong;Joo, Hyeok-Jong;Jin, Fan-Long
    • Elastomers and Composites
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    • v.40 no.3
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    • pp.166-173
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    • 2005
  • Effect of thermal aging on the weight loss and water absorption of epoxy adhesives was investigated in the presence of three types of different hardeners, such as D-230, G-5022, and HN-2200. Thermal and mechanical properties of the cured epoxy resins were also studied througth the glass transition temperature and shear adhesion strength measurements. Weight losses of DGEBA/D-230 and DGEBA/HN- 2200 systems were not varied. However, the weight of DGEBA/G-5022 system was significantly decreased with increasing the thermal aging time. The water absorption of the specimens was increased as the thermal aging time increased except that using G-5022. DEGBA/HN-2200 system showed higher $T_g$ value than those of other systems, due to the formation of the fine three-dimensional network structure containing aliphatic ring. Shear adhesion strength of all systems was increased with increasing the thermal aging tine, which is attributed to increased degree of cure and fine three-dimensional network structure formation. And $T_g$ values and shear adhesion strength of all specimens exposed to water was decreased as the immersion time increased.

Accelerating Effects of Ultrasonic Irradiation on Reaction Rates for the Asymmetric Ring Opening Reaction of Epoxides (초음파 조사에 의한 에폭사이드 비대칭 고리열림 반응의 속도 증진 효과)

  • Lee, Yae Won;Park, Geun Woo;Kim, Geon Joong
    • Applied Chemistry for Engineering
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    • v.30 no.3
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    • pp.365-370
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    • 2019
  • In this study, effects of the ultrasonic irradiation during the reaction process were investigated for the enantioselective kinetic resolution (EKR) reaction of racemic epoxides in the presence of chiral cobalt salen catalysts, as compared to that of using the conventional mechanical stirring. In order to compare catalytic activities, the chiral cobalt salen complexes having $AlCl_3-$, $BF_3-$ and nitrobenzenesulfonic acid (NBSA) were synthesized and used as catalysts, and then three kinds of the racemic epoxides such as ephichlorohydrine (ECH), epoxy phenoxypropane (EPP) and propylene oxide (PO) were used as reactants. In addition, EKR reactions have been performed using the water and methanol as nucleophiles, respectively. The unique contribution of ultrasonic irradiation as a powerful mixing medium was evaluated in this study to improve the kinetics in comparison to the conventional mechanical agitation during EKR reactions. The reaction time to obtain the highest 99 ee% became shorten more than that of above 60%, when the ultrasonic irradiation was used. This result may be interpreted by the cavitation effect of ultrasound in the solution, generating a powerful shear force for the very violent mixing.