• Title, Summary, Keyword: quasi-static test

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Finite Element Modeling of Low Density Polyurethane Foam Material (저밀도 폴리우레탄 포옴재료의 유한요소 모델링)

  • 김원택;최형연
    • Transactions of the Korean Society of Automotive Engineers
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    • v.4 no.2
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    • pp.183-188
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    • 1996
  • The compressive stress-strain response of Low Density Polyurethane foam material is modeled using the finite element method. A constitutive equation which include experimental constants based on quasi-static and dynamic uniaxial compression test is proposed. Impact test with different impactor masses and velocities are performed to verify the proposed model. The comparison between impact test and finite element analysis shows good agreements.

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Quasi-static Analysis of Vehicle Seatbelt Using Analysis of Variance and Improvement of Tensile Test Correlation (분산 분석을 이용한 자동차 안전벨트 준정적 해석과 인장시험 상관성 개선)

  • Lee, Kwangseop;Eo, Youngwoo;Kim, Samsung;Kim, Dooyong;Song, Taeckrim;Lee, Kyeongsang
    • Transactions of the Korean Society of Automotive Engineers
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    • v.24 no.3
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    • pp.273-278
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    • 2016
  • This study makes a relative comparison of the results of tensile test and quasi-static analysis using AGL(Adjuster Guide Loop) model that plays a role in adjusting the height of shoulder belt, of the components of the vehicle seatbelt system and attempts to propose a method of reducing the error rate of the quasi-static analysis technique effectively. This study selects two major factors affecting the result of an analysis, draws the result of analysis through the method of experimental design, one of the statistical techniques and understands the contribution rate of the major factors affecting the result of the analysis through ANOVA(Analysis of Variance).

Research of Plastic response by Quasi-Static Test for Circulr Hollow R.C. Bridge Pier (준정적 실험에 의한 중공원형 콘크리트 교각의 소성응답 연구)

  • 정영수
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.247-255
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    • 1999
  • Because of relatively heavy dead weight of concrete itself and unavoidable heat of massive concrete in bridge piers circular hollow columns are widely used in Korean highway bridges Since the occurrence of 1995 Kobe earthquake there have been much concern about seismic design for various infrastructures inclusive of bridge structures. It is however understood that there are not much research works for nonlinear behavior circular hollow columns subjected to earthquake motions. The ultimate of this experimental research is to investigate nonlinear behavior of hollow reinforced concrete bridge piers under the quasi-static cyclic load test and than to enhance their ductility by strengthening the plastic hinge region with glassfiber sheets. It can be concluded from Quasi-static test for 7 bridge piers that approximate 4-5 ductility factor can be experimentally obtained for bridge piers nonseismically designed in conventional way which approximate 5-6 ductility factor for those seismically designed.

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A Study on the Axial Crush Analysis of a Rectangular Tube with Experimental Comparison (사각관의 붕괴해석 및 실험에 관한 연구)

  • 강신유;한동철
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.10
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    • pp.2555-2562
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    • 1993
  • In this paper, the axial crush of the rectangular STS304 tube is analyzed using DYNA3D, and 10 models are tested under quasi-static load. The deformed shapes of analysis and test are present, and the analysis results are compared with the results of quasi-static test. This paper describes that free rotational boundary condition causes a very similar deformed shapes to expermental results, and using the elastic buclking modes as initial imperfecion shapes, the deformed shapes are very close to the experimental shapes.

Quasi Static Test of Real Scaled RC Piers with Low-Aspect Ratio (저형상비 RC교각의 실물모형 준정적실험)

  • Cho, Chang-Beck;Kwahk, Im-Jong;Kim, Young-Jin
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.218-221
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    • 2006
  • The past Korean Bridge Design Specifications have no limitation on the amount of lap splices of longitudinal bars in the plastic hinge zone of piers. A majority of bridge piers which have been non-seismically designed might have some lap splices in plastic hinge zone. Also a number of those piers in Korea have a low aspect ratio(height/section area). So, some problems such as low ductility behavior may happen. In this study, the real pier which was non-seismically designed and has a low aspect ratio was selected for the quasi-static tests. Two groups of full scaled RC pier models of which aspect ratios are about 2.26 and about 2.67 were fabricated. And then, quasi-static tests according to the drift level history method were implemented. From the test results, the failure of these test specimens have been shown in the complex shear-flexural or shear modes. The low aspect ratio and the lap splice have largely influenced on the seismic performance of bridge piers.

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Strength and stiffness of cold-formed steel portal frame joints using quasi-static finite element analysis

  • Mohammadjani, Chia;Yousefi, Amir M.;Cai, Shu Qing;Clifton, G. Charles;Lim, James B.P.
    • Steel and Composite Structures
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    • v.25 no.6
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    • pp.727-734
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    • 2017
  • This paper describes a quasi-static finite element analysis, which uses the explicit integration method, of the apex joint of a cold-formed steel portal frame. Such cold-formed steel joints are semi-rigid as a result of bolt-hole elongation. Furthermore, the channel-sections that are being connected have a reduced moment capacity as a result of a bimoment. In the finite element model described, the bolt-holes and bolt shanks are all physically modelled, with contact defined between them. The force-displacement curves obtained from the quasi-static analysis are shown to be similar to those of the experimental test results, both in terms of stiffness as well as failure load. It is demonstrated that quasi-static finite element analysis can be used to predict the behavior of cold-formed steel portal frame joints and overcome convergence issues experienced in static finite element analysis.

Application of Wavelet Transform in Estimating Structural Dynamic Parameters by Vehicle Loading Test (차량재하시험에 의한 구조물 동특성 평가에 웨이블렛변환의 이용)

  • Park, Hyung-Ghee
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.9 no.2
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    • pp.129-136
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    • 2005
  • The vehicle loading test under the strict traffic control is generally carried out as a present practice in an evaluation process of the bearing capacity of a bridge. The quasi-static load test is recently proposed to mitigate the traffic condition of test, and analyze the disturbed acceleration time-history data of free vibration due to the ambient traffic on the bridge by Fourier transform to calculate only the natural frequencies of the bridge. The calculated frequencies have some errors due to the analysis technique as well as the influence of ambient traffic loads, and in addition to it is cumbersome to obtain the free vibration data during a quasi-static load test. In this study, the wavelet transform technique using Morlet wavelet is used to analyze the acceleration data recorded during a quasi-static load test on a bridge and calculate the natural frequencies and the modal damping ratios of the bridge. The study results show that the wavelet transform technique is a reliable and reasonable method to analyze test data and obtain the natural frequencies and the modal damping ratios of a bridge regardless of the data types i.e. free or forced vibrations.

Compliance Effect Modeling Based on Quasi-Static Analysis for Real-Time Multibody Vehicle Dynamics (실시간 다물체 차량 해석을 위한 준정적법의 컴플라이언스 효과 모델링)

  • Kim, Sung-Soo;Jeong, Wan-Hee;Ha, Kyoung-Nam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.2
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    • pp.162-169
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    • 2008
  • Compliance effect consideration method for real-time multibody vehicle dynamics is proposed using quasi-static analysis. The multibody vehicle model without bush elements is used based on the subsystem synthesis method which provides real-time computation on the multibody vehicle model. Reaction forces are computed in the suspension subsystem. According to deformation from the quasi-static analysis using reaction forces and bush stiffness, suspension hardpoint locations and suspension linkage orientation are changed. To validate the proposed method, quarter car simulations of McPherson strut and multilink suspension subsystems are performed. Full car bump run simulations and fish hook handling test simulations are also carried out comparing with the ADAMS vehicle model with bush elements. CPU times are also measured to see the real-time capabilities of the proposed method.

Influence of dimensional ratio on collapse characteristics for the thin-walled structures of light weight (경량화용 박육부재의 형상비가 압궤특성에 미치는 영향)

  • 정종안;김정호;양인영
    • Journal of the Korean Society of Safety
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    • v.13 no.3
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    • pp.11-23
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    • 1998
  • In this study, collapse test of thin-walled structure is performed under axially quasi-static and impact load in collapse characteristic to develop the optimum structural member for a light-oriented automobile. Furthermore, the energy-absorbing capacity is observed according to the variety of configuration(circular, square), aspect ratio in aluminum specimen to obtain basic data for the improved member of vehicle. In both quasi-static and impact collapse test, Al circular specimens collapse, in general, with axisymmetric mode in case of thin thickness while collapse with non-axisynmetric mode according to the thickness increase. For Al rectangular specimens, they collapse with axisymmetric mode in case of thin thickness, with mixed collapse mode according to the increase of thickness. In terms of initial max. load, Al square specimen turns out the best member among specimens, and then Al square, circular and circular with large scaling ratio, respectively. In case of quasi-static compression test, the absorbed energy per unit volume and mass shows higher in Al circular specimen, and then Al square, circular with large scaling ratio, respectively, according to shape ratio the absorbed energy per unit volume and mass in case of max. impact compression load is higher than that of static load. But the absorbed energy per unit volume and mass shows that Al circular specimen is the best member. Especially, unlike max. compression loan, the absorbed energy per unit volume and mass in impact test turns out the low value.

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An Experimental Study on the Axial Collapse Characteristics of Hat and Double Hat Shaped Section Members at Various Velocities

  • Cha, Cheon-Seok;Chung, Jin-Oh;Yang, In-Young
    • Journal of Mechanical Science and Technology
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    • v.18 no.6
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    • pp.924-932
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    • 2004
  • In this study, the axial collapse tests were performed under either static (or quasi-static) or impact loads with several collapse velocities based on the expectation that para-closed sections of the front-end side members (spot welded hat and double hat shaped section members) would show quite different collapse characteristics from those for seamless section. The test results showed that both of the hat and double hat shaped section members failed in the stable sequential collapse mode in the static or quasi-static collapse tests, while the double hat shaped section members underwent the unstable collapse mode especially when the impact velocity is high. The mean collapse loads in the hat shaped section members increase with collapse velocity for all the cases of the static, quasi-static, and impact collapse tests. In the double hat shaped section members, however, the mean collapse loads decrease with increase in collapse velocity in the impact tests.