• Title/Summary/Keyword: Mechanical load test

Search Result 1,539, Processing Time 0.03 seconds

Experimental Study on the Load Carrying Performance and Driving Torque of Gas Foil Thrust Bearings (가스 포일 스러스트 베어링의 하중지지 성능 및 구동 토크에 관한 실험적 연구)

  • Kim, Tae Ho;Lee, Tae Won;Park, Moon Sung;Park, Jungmin;Kim, Jinsung;Jeong, Jinhee
    • Tribology and Lubricants
    • /
    • v.31 no.4
    • /
    • pp.141-147
    • /
    • 2015
  • Gas foil thrust bearings (GFTBs) have attractive advantages over rolling element bearings and oil film thrust bearings, such as oil-free operation, high speed stability, and high-temperature operation. However, GFTBs have lower load carrying capacity than the other two types of bearings owing to the inherent low gas viscosity. The load carrying capacity of GFTBs depends mainly on the compliance of the foil structure and the formed hydrodynamic wedge, where the gas pressure field is generated between the top foil and the thrust runner. The load carrying capacity of the GFTBs is very important for the suitable design of oil-free turbomachinery with high performance. The aim of the present study is to identify the characteristics of the load carrying performance of GFTBs. A new test rig for the experimental measurements is designed to provide static loads up to 800 N using a pneumatic cylinder. The maximum operating speed of the driving motor is 30,000 rpm. A series of experimental tests—lift-off test, static load performance test, and maximum load capacity test—estimate the performance of a six-pad GFTB, in terms of the static load, driving torque, and temperature. The maximum load capacity is determined by increasing the static load until the driving torque rises suddenly with a sharp peak. The test results show that the torque and temperature increase linearly with the static load. The estimated maximum load capacity per unit area is approximately 80.5 kPa at a rotor speed of 25,000 rpm. The test results can be used as a design guideline for GFTBs for realizing oil-free turbomachinery.

Structural Behavior of RC Columns with Mechanically Anchored Crossties under Cyclic Loading (기계적 정착된 전단보강근을 가진 RC 기둥의 구조적 거동)

  • Lee, Sung-Ho;Chun, Sung-Chul;Oh, Bo-Hwan;Nah, Hwan-Sean;Kim, Sang-Koo
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • 2005.05a
    • /
    • pp.59-62
    • /
    • 2005
  • Seven columns laterally reinforced with either mechanically anchored crossties or conventional crossties under cyclic loading are tested. 4 columns are specimens for flexural strength and 3 columns are for shear strength. Main variable is anchorage types of crossties. Conventional hooks, 180$^{\circ}$ standard hook-mechanical anchorage and all mechanical anchorage type are used. The specimens are tested under 10$\%$ axial load of nominal axial capacity of the columns combined with increasing lateral load. From the flexure test, it is found that columns with mechanical anchorages exhibit superior performance in terms of ductility and energy dissipation. The crossties with mechanical anchorages reduce buckling length of longitudinal rebar. From the shear test, it is found that. 3 specimens exhibit almost the same strength, displacement, and shear failure mode at ductility factor =2.

  • PDF

Analysis of Agricultural Working Load Experiments for Reduction Gear Ratio Design of an Electric Tractor Powertrain (전기구동 파워트레인의 감속기어비 설계를 위한 농용 트랙터의 작업 부하 분석)

  • Kim, Jung-Yun;Park, Yeong-Il
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.20 no.5
    • /
    • pp.138-144
    • /
    • 2012
  • Recent environmental issues such as exhaust gas and greenhouse effect make the agricultural machinery market takes into account the hybrid and electric propulsion technology used in automotive engineering. Generally the agricultural machinery, particularly an agricultural tractor, needs large load capacity and long continuous operating time comparing with conventional vehicles. In case of a pure electric tractor, it is necessary for considering large capacity batteries and long charging time. Therefore we take an AER extended PHEV (All Electric Range extended Plug-in Hybrid Electric Vehicle) power transmission system in developing an electric tractor in this study. First we propose a PHEV powertrain structure in order to substitute the conventional diesel engine equipped tractor. And we performed the road tests using a conventional mechanical tractor with various load conditions, which were classified and statistically treated real agricultural works. The test results were analysed with respect to the power characteristics of the power source. Finally using the test result, we designed two-stepped reduction gear ratios in the proposed an electric tractor powertrain for carrying out typical agricultural works.

Performance Monitoring and Load Analysis of Wind Turbine (풍력발전기의 성능 모니터링 및 하중분석)

  • Bae, Jae-Sung;Kim, Sung-One;Youn, Joung-Eun;Kyung, Nam-Ho
    • 유체기계공업학회:학술대회논문집
    • /
    • 2004.12a
    • /
    • pp.385-389
    • /
    • 2004
  • Test facilities for the wind turbine performance monitoring and mechanical load measurements are installed in Vestas 100 kW wind turbine in Wollyong test site, Jeju island. The monitoring system consists of Garrad-Hassan T-MON system, telemetry system for blade load measurement, various sensors such as anemometer, wind vane, strain gauge, power meter, and etc. The experimental procedure for the measurement of wind turbine loads, such as edgewise(lead-lag) bending moment, flapwise bending moment, and tower base bending moment, has been established. Strain gauges are on-site calibrated against load cell prior to monitoring the wind turbine loads. Using the established monitoring system, the wind turbine is remotely monitored. From the measured load data, the load analysis has been performed to obtain the load power spectral density and the fatigue load spectra of the wind turbine.

  • PDF

Finite Element Analysis of Mechanical Behavior of Bolt Tightened in Plastic Region (소성역 체결 볼트의 기계적 거동 유한요소해석)

  • Cho, Sung-San;Shin, Chun-Se
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.18 no.3
    • /
    • pp.37-42
    • /
    • 2010
  • Plastic region tightening is widely used in critical bolted joints in internal combustion engines in order to reduce the engine weight by maximizing the use of load-carrying capacity of bolt. Mechanical behavior of bolt tightened in plastic region under external axial tensile load is investigated for various friction conditions using three dimensional finite element analysis. The behavior of bolt tightened in elastic region as well as that in tensile test are investigated for comparison. Tightening process is simulated by rotating the bolt in order to examine the friction effect realistically. It is revealed that the bolt tightened in plastic region can carry more external load until the joint is opened, and yields at lower bolt load than the bolt tightened in elastic region. The friction coefficient has effect on the yield load, but not on the load-carrying capacity. Moreover, the scatter in the bolt preload due to friction begins with plastic deformation of bolt in the angle tightening control, whereas it begins with the onset of tightening in the torque tightening control. The observations are interpreted with the residual torsional stress in the bolt generated during the tightening.

EFFECT OF RESIDUAL STRESS BY SHOT PEENING ON FATIGUE STRENGTH OF LCV LEAF SPRING

  • BAE D. H.;SOHN I. S.;JUNG W. S.;KIM N. S.;JUNG W. W.;PARK S. C.
    • International Journal of Automotive Technology
    • /
    • v.6 no.6
    • /
    • pp.671-676
    • /
    • 2005
  • Spring is one of major suspension part of the light commercial vehicle (LCV). In the manufacturing process it is shot-peened to improve its fatigue strength. In this paper, residual stresses by shot peening were calculated through finite element analysis, and the effects of these residual stresses on fatigue strength of leaf spring were evaluated. Fatigue tests were performed with two kinds of specimens; one is actual leaf spring assembly, and the other is simulated 3-point bending specimen. Fatigue tests were performed under the loading condition that was measured on the proving ground. From the results, the maximum load-fatigue life relation of leaf spring was defined, and test results of 3 point bending specimen are in good agreement with those of leaf spring assembly. The effects of residual stresses by shot peening on fatigue strength of leaf spring is not large in the high load range, however, in the low load range, its effects were not negligible.

A Study on the Looseness Property of a Tiebar (타이바의 풀림 특성에 관한 연구)

  • Bae B.K.;Park H.S.;Seok C.S.;Park D.Y.
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • 2005.06a
    • /
    • pp.1363-1366
    • /
    • 2005
  • The tiebar is used by joint for keeping from deformation by conserving tensile load between two structure. The tiebar, bolt joining type, is combined by tiebar and clevis like bolt and nut. By coupled, it maintains tensile load. While it goes through repeated load, it occurs to loose because joining force between clevis and nuts is reduced. So, continuos maintenance is needed such as making tighter periodically, repairing the broken part and so on. For that reason, this paper calculates necessary torque unfastening joint for conventional tiebar and presenting tiebar theoretically and then consider the reason that conventional bolt-typed tiebar unties. Also, through vibration untied test for two types of tiebar we confirm that presenting tiebar have a improvement of unfastening when we compare with the conventional one.

  • PDF

Fatigue Strength Evaluation of the Aluminum Car body of Urban Transit Unit by Large Scale Dynamic Load Test (도시철도차량 알루미늄 차체의 동적 하중 시험에 의한 피로 강도 평가)

  • Seo, Sung-Il;Park, Choon-Soo;Shin, Byung-Cheon
    • Proceedings of the KSME Conference
    • /
    • 2003.11a
    • /
    • pp.1051-1055
    • /
    • 2003
  • Aluminum carbody for rolling stocks is light and perfectly recycled, but includes severe defects which are very dangerous to fatigue strength. Structural integrity assessment for the carbody by static load test has been performed up to date. In this study, to evaluate fatigue strength of the aluminum carbody of urban transit unit. a testing method to simulate dynamic loading condition was proposed and the fatigue strength of the carbody was evaluated. The dynamic load test results showed that the alternating stress ranges were different from the estimated ranges based on the static test results. Excessive stress ranges at the center are thought to come from the flexible motion of the carbody. published fatigue test data for aluminum components, but variation of alternating acceleration along the length due to flexibility of carbody yielded unexpected results. Because fatigue strength based on the static test results may be overestimated at the center, modification of testing method is necessary.

  • PDF

Design and Construction of a High Temperature Creep Tester for Thin Film Specimens (박막시험편용 고온 크리프 시험기의 설계 및 제작)

  • Ko, Gyoung-Dek;Lee, Sang-Shin;Kang, Ki-Ju
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.31 no.2 s.257
    • /
    • pp.253-259
    • /
    • 2007
  • A new material tester has been developed to measure mechanical properties of thin film specimens at high temperature. It is useful for observing oxide film growth or local deformation on the surface, and for measuring creep strength. Main characteristics of the tester is as follows; First, high temperature is achieved by Joule heating generated by electricity passing through the specimen, which does not need to enclose the specimen by a furnace or a heating chamber. The exposed specimen enables one to observe the surface during the test. Because the overall size of the test rig is compact, the whole test rig can be placed in a chamber for environmental controlled tests. The loading device is from a level scales. Not only static load with fixed counter weight, but also variable load by moving counter weight controlled remotely can be applied for an ordinary creep test and creep-fatigue test, respectively. The detail of the construction, operation principle, and the specification are described. And also, an example of test result obtained using the creep tester is presented.

Nano-Mechanical and Tribological Characteristics of Ultra-Thin Amorphous Carbon Film Investigated by AFM

  • Chung, Koo-Hyun;Lee, Jae-Won;Kim, Dae-Eun
    • Journal of Mechanical Science and Technology
    • /
    • v.18 no.10
    • /
    • pp.1772-1781
    • /
    • 2004
  • The mechanical as well as tribological characteristics of coating films as thin as a few nm become more crucial as applications in micro-systems grow. Especially, the amorphous carbon film has a potential to be used as a protective layer for micro-systems. In this work, quantitative evaluation of nano-indentation, scratching, and wear tests were performed on the 7nm thick amorphous carbon film using an Atomic Force Microscope (AFM). It was shown that AFM-based nano-indentation using a diamond coated tip can be feasibly utilized for mechanical characterization of ultra-thin films. Also, it was found that the critical load where the failure of the carbon film occurred was about 18${\mu}$N by the ramp load scratch test. Finally, the wear experimental results showed that the quantitative wear rate of the carbon film ranged 10$\^$-9/~10$\^$-8/ ㎣ /N cycle. These experimental methods can be effectively utilized for a better understanding the mechanical and tribological characteristics at the nano-scale.