• Title, Summary, Keyword: failure mechanism

Search Result 1,395, Processing Time 0.047 seconds

Failure Mechanism of Headed Reinforcement including Bond Failure (부착파괴를 고려한 Headed Reinforcement의 파괴메카니즘)

  • 박종욱;홍성걸
    • Proceedings of the Korea Concrete Institute Conference
    • /
    • /
    • pp.234-237
    • /
    • 2003
  • Previous researches about headed reinforcement have not been concerned about bond failure which is quite important is some cases. In this paper, failure mechanism including bond failure was presented in order to define the contribution of bond stress at the time failure occurs. Examined with design codes and test results, it is proved to be rational to consider the contribution of bond stress in determining the ultimate pull-out capacity of headed reinforcement. Direct adaptation of design code for anchor bolt without modification for the contribution of bond stress will lead to underestimate the capacity of headed reinforcement.

  • PDF

Study on the Failure Mechanism of a Chip Resistor Solder Joint During Thermal Cycling for Prognostics and Health Monitoring (고장예지를 위한 온도사이클시험에서 칩저항 실장솔더의 고장메커니즘 연구)

  • Han, Chang-Woon;Park, Noh-Chang;Hong, Won-Sik
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.35 no.7
    • /
    • pp.799-804
    • /
    • 2011
  • A thermal cycling test was conducted on a chip resistor solder joint with real-time failure monitoring. In order to study the failure mechanism of the chip resistor solder joint during the test, the resistance between both ends of the resistor was monitored until the occurrence of failure. It was observed that the monitored resistance first fluctuated linearly according to the temperature change. The initial variation in the resistance occurred at the time during the cycle when there was a decrease in temperature. A more significant change in the resistance followed after a certain number of cycles, during the time when there was an increase in the temperature. In order to explain the failure patterns of the solder joint, a mechanism for the solder failure was suggested, and its validity was proved through FE simulations. Based on the explained failure mechanism, it was shown that prognostics for the solder failure can be implemented by monitoring the resistance change in a thermal cycle condition.

Design of Accelerated Test for Reliability Assurance of SHAFT Assembly (SHAFT 어셈블리 신뢰성 보증을 위한 가속시험의 설계)

  • 김준홍;오근태;김명수
    • Journal of the Society of Korea Industrial and Systems Engineering
    • /
    • v.23 no.61
    • /
    • pp.75-87
    • /
    • 2000
  • This paper proposes a procedure for designing an accelerated test using SMAT(Stress, (failure) Mechanism and Test) model describing the relation among stress, failure mode/mechanism and test method. In SMAT model the stresses to be applied are derived from the environmental factor analysis, the relative importance of those stresses can be estimated using AHP(Analytic Hierarchy Process) and failure mode/mechanism and test method are derived from the fields failure information and FMEA(Failure Mode and Effect Analysis). By applying the procedure we can make a selection of major factors to cause the failure of assembly and design the accelerated test using DOE(Design of Experiments) The procedure is illustrated with an qualification test case study of washing machine shaft assembly in "A" electric appliance company.

  • PDF

Lifetime prediction of the engine mount about the environment temperature variation (환경 온도변화에 대한 자동차용 엔진마운트의 수명 예측)

  • Kim, Hyung Min;Wei, Shin Hwan;Yoon, Sin Il;Shin, Ik Jae;Kim, Gyu Ro
    • Journal of Applied Reliability
    • /
    • v.13 no.1
    • /
    • pp.65-76
    • /
    • 2013
  • In order to assess the reliability of engine mount for a vehicles, life test model and procedure are developed. By using this method, failure mechanism and life distribution are analyzed. The main results are as follows; i) the main failure mechanism is degradation failure of engine mount rubber by fatigue failure at dynamic load. ii) temperature is a second factor to affect a failure. iii) the life distribution of engine mount module is fitted well to Weibull life distribution and the shape parameter is 18.4 and the accelerated life model of that is fitted well to Arrhenius model.

Roof collapse of shallow tunnel in layered Hoek-Brown rock media

  • Yang, X.L.;Li, K.F.
    • Geomechanics and Engineering
    • /
    • v.11 no.6
    • /
    • pp.867-877
    • /
    • 2016
  • Collapse shape of tunnel roof in layered Hoek-Brown rock media is investigated within the framework of upper bound theorem. The traditional collapse mechanism for homogeneous stratum is no longer suitable for the present analysis of roof stability, and it would be necessary to propose a curve failure mode to describe the velocity discontinuity surface in layered media. What is discussed in the paper is that the failure mechanism of tunnel roofs, consisting of two different functions, is proposed for layered rock media. Then it is employed to investigate the impending roof failure. Based on the nonlinear Hoek-Brown failure criterion, the collapse volume of roof blocks are derived with the upper bound theorem and variational principle. Numerical calculations and parametric analysis are carried out to illustrate the effects of different parameters on the shape of failure mechanism, which is of overriding significance to the stability analysis of tunnel roof in layered rock media.

Shear mechanism and bearing capacity calculation on steel reinforced concrete special-shaped columns

  • Xue, J.Y.;Chen, Z.P.;Zhao, H.T.;Gao, L.;Liu, Z.Q.
    • Steel and Composite Structures
    • /
    • v.13 no.5
    • /
    • pp.473-487
    • /
    • 2012
  • An experimental study was performed to investigate the seismic performance of steel reinforced concrete (SRC) special-shaped columns. For this purpose, 17 steel reinforced concrete special-shaped column specimens under low-cyclic reversed load were tested, load process and failure patterns of the specimens with different steel reinforcement were observed. The test results showed that the failure patterns of these columns include shear-diagonal compression failure, shear-bond failure, shear-flexure failure and flexural failure. The failure mechanisms and characteristics of SRC special-shaped columns were also analyzed. For different SRC special-shaped columns, based on the failure characteristics and mechanism observed from the test, formulas for calculating ultimate shear capacity in shear-diagonal compression failure and shear-bond failure under horizontal axis and oblique load were derived. The calculated results were compared with the test results. Both the theoretical analysis and the experimental results showed that, the shear capacity of T, L shaped columns under oblique load are larger than that under horizontal axis load, whereas the shear capacity of +-shaped columns under oblique load are less than that under horizontal axis load.

Earthquake Resistance Design for a Typical Bridge Substructure (일반교량 하부구조의 내진설계)

  • Kook, Seung-Kyu
    • Journal of the Computational Structural Engineering Institute of Korea
    • /
    • v.24 no.3
    • /
    • pp.283-288
    • /
    • 2011
  • For the earthquake resistance design designer should provide that structural yielding process is principally designed with the ductile failure mechanism. In order to get the ductile failure mechanism for typical bridges, pier columns yielding should occur before that of connections. However domestic bridge design with unnecessary stiff substructure leads to unnecessary seismic loads and makes it difficult to get the ductile failure mechanism. Such a problem arises from the situation that earthquake resistant design is not carried out in the preliminary design step. In this study a typical bridge is selected as an analysis bridge and design strengths for connections and pier columns are determined in the preliminary design step by carrying out earthquake resistant design. It is shown through this procedure that it is possible to get the ductile failure mechanism with structural members determined by other design.

Three-dimensional limit analysis of seismic stability of tunnel faces with quasi-static method

  • Zhang, B.;Wang, X.;Zhang, J.S.;Meng, F.
    • Geomechanics and Engineering
    • /
    • v.13 no.2
    • /
    • pp.301-318
    • /
    • 2017
  • Based on the existing research results, a three-dimensional failure mechanism of tunnel face was constructed. The dynamic seismic effect was taken into account on the basis of quasi-static method, and the nonlinear Mohr-Coulomb failure criterion was introduced into the limit analysis by using the tangent technique. The collapse pressure along with the failure scope of tunnel face was obtained through nonlinear limit analysis. Results show that nonlinear coefficient and initial cohesion have a significant impact on the collapse pressure and failure zone. However, horizontal seismic coefficient and vertical seismic proportional coefficient merely affect the collapse pressure and the location of failure surface. And their influences on the volume and height of failure mechanism are not obvious. By virtue of reliability theory, the influences of horizontal and vertical seismic forces on supporting pressure were discussed. Meanwhile, safety factors and supporting pressures with respect to 3 different safety levels are also obtained, which may provide references to seismic design of tunnels.

Development of Failure Mechanism for Rotorcraft Landing Gear (회전익기 착륙장치 파손장치 개발)

  • Shin, Jeong-Woo;Kim, Tae-Uk;Hwang, In-Hee;Jo, Jeong-Jun;Lee, Jeong-Sun;Park, Chong-Yeong
    • Proceedings of the KSME Conference
    • /
    • /
    • pp.497-501
    • /
    • 2008
  • To improve occupants' safety in an emergency, crashworthy design is necessary to rotorcraft design and development. To improve crashworthiness capability, most of the crash energy should be absorbed by rotorcraft and the energy transmitted to the occupants should be minimized. To absorb the crash energy efficiently, the individual energy attenuation provided by landing gear, structure, fuel tank and seats should be considered totally. Especially, landing gear has the important role for crashworthy design because landing gear absorbs relatively large energy for the crash landing. In addition, military specifications require failure of landing gear shall not increase danger to any occupants by penetration of the airframe. To meet the specification requirements, failure mechanism should be prepared so that landing gear is collapsed safely and doesn't penetrate the airframe. In this study, design of failure mechanism which is necessary for the rotorcraft landing gear was performed and the results were presented.

  • PDF

Investigation on Failure Mechanism of Geosynthethic Reinforced Slopes (보강토 구조물 파괴 메카니즘에 관한 연구)

  • Yoo, Chung-Sik;Kim, Ki-Yeon;Lee, Sung-Woo;Lee, Bong-Won
    • Journal of the Korean Geosynthetics Society
    • /
    • v.4 no.2
    • /
    • pp.19-28
    • /
    • 2005
  • This paper presents a laboratory investigation on the failure mechanism of geosynthetic reinforced slopes using 1/5-scale reduced model. The components of the model were selected with due consideration of the similitude law and the step-by-step actual wall construction procedure was closely simulated. The model tests successfully replicated the failure mechanism with relative density, slope and vertical spacing.

  • PDF