• Title/Summary/Keyword: Failure Model

Search Result 4,605, Processing Time 0.032 seconds

Effect of Ground Subsidence on Reliability of Buried Pipelines (지반침하가 매설배관의 건전성에 미치는 영향)

  • 이억섭;김동혁
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.21 no.1
    • /
    • pp.173-180
    • /
    • 2004
  • This paper presents the effect of varying boundary conditions such as ground subsidence, internal pressure and temperature variation for buried pipelines on failure prediction by using a failure probability model. The first order Taylor series expansion of the limit state function incorporating with von-Mises failure criteria is used in order to estimate the probability of failure mainly associated with three cases of ground subsidence. Using stresses on the buried pipelines, we estimate the probability of pipelines with von-Mises failure criterion. The effects of varying random variables such as pipe diameter, internal pressure, temperature, settlement width, load for unit length of pipelines, material yield stress and pipe thickness on the failure probability of the buried pipelines are systematically studied by using a failure probability model for the pipeline crossing ground subsidence regions which have different soil properties.

Failure Probability Model of Buried Pipeline (매설배관의 파손 확률 모델)

  • Lee, Eok-Seop;Pyeon, Jang-Sik
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.18 no.11
    • /
    • pp.116-123
    • /
    • 2001
  • A failure probability model based on Von-Mises failure criterion and the standard normal probability function is proposed. The effects of varying boundary conditions such as nearby cavity, backfill, load cycle and corrosion on failure probability of the buried pipes are systematically investigated. The location of cavity is found to affect failure probability of buried pipeline within a certain limit. It is noted that the flexibility of backfill plays a great role to change the failure probability of buried pipeline. Furthermore, the corrosion gives less effects than other boundary conditions such as cavity, load as cavity, load cycle, and backfill to the failure probability of buried pipeline.

  • PDF

Reliability for Failure Rates Different over Time Intervals (고장률이 시간 구간별로 다른 경우의 신뢰도)

  • Jeon, Tae-Bo
    • Journal of Industrial Technology
    • /
    • v.27 no.B
    • /
    • pp.245-253
    • /
    • 2007
  • Failure rate serves as a pivotal role in reliability study. Of all, the constant failure rate is the most popularly used in field exercises. In reality, however, the electrical and electronic parts' life is represented by not only the constant failure rate but the decreasing and/or increasing failure rates. Explicit consideration and incorporation of them into the model development may yield more desirable results. In this study, we built a reliability model for failure rates varying over time intervals and derived well known measures such as probability density function, reliability function, mean life, moments, and mission time. We then evaluated mean life with consideration of the first-year multiplier and compared the results those with constant failure rate. The results given in the study may provide a reference applying for practical decision making.

  • PDF

A Comparative Study of Software finite Fault NHPP Model Considering Inverse Rayleigh and Rayleigh Distribution Property (역-레일리와 레일리 분포 특성을 이용한 유한고장 NHPP모형에 근거한 소프트웨어 신뢰성장 모형에 관한 비교연구)

  • Shin, Hyun Cheul;Kim, Hee Cheul
    • Journal of Korea Society of Digital Industry and Information Management
    • /
    • v.10 no.3
    • /
    • pp.1-9
    • /
    • 2014
  • The inverse Rayleigh model distribution and Rayleigh distribution model were widely used in the field of reliability station. In this paper applied using the finite failure NHPP models in order to growth model. In other words, a large change in the course of the software is modified, and the occurrence of defects is almost inevitable reality. Finite failure NHPP software reliability models can have, in the literature, exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, proposes the inverse Rayleigh and Rayleigh software reliability growth model, which made out efficiency application for software reliability. Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on mean square error (MSE) and coefficient of determination($R^2$), for the sake of efficient model, were employed. In order to insurance for the reliability of data, Laplace trend test was employed. In many aspects, Rayleigh distribution model is more efficient than the reverse-Rayleigh distribution model was proved. From this paper, software developers have to consider the growth model by prior knowledge of the software to identify failure modes which can helped.

A Determination of an Optimal Repair Number under Achieved Availability Constraint (성취가용도를 고려한 최적 수리횟수 결정모델에 관한 연구)

  • Na, In-Sung;Park, Myeong-Kyu
    • Journal of Applied Reliability
    • /
    • v.7 no.1
    • /
    • pp.13-22
    • /
    • 2007
  • A preventive maintenance model, caller FNBM (${\alpha},{\delta},{\gamma}$) model, is proposed to decide an optimal repair number under achieved availability requirements (r) along with taking two types of failures (repairable or irrepairable) into account. In this model, the current system is replaced by a new one in case when it doesn't meet the achieved availability requirement, even though it is repairable failure; Othewise it is replaced in time of the first irrepairable failure. Assumed that the j-th failure is repairable with probability ${\alpha}_j$ minimal repairs are allowed for repairable failure between replacements. Expected cost rate for preventive maintenance model is developed using NHPP (Non - Homogeneous Poisson Process) in order to de term in the optimal number $n^*$, also numerical examples are shown in order to explain the proposed model. Since the proposed FNBM (${\alpha},{\delta},{\gamma}$) model includes Park FNBM model (1979) and Nakagawa FNBM (p) model (1983) m this proposed model is thought to be better than previous model, especially for weapon system which requires availability as primary parameter.

  • PDF

Development of Optimum Global Failure Prediction Model for Steam Generator Tube with Two Parallel Cracks (평행한 두 개의 균열이 존재하는 증기발생기 세관의 최적 광범위파손 예측모델 개발)

  • Moon Seong ln;Chang Yoon Suk;Lee Jin Ho;Song Myung Ho;Choi Young Hwan;Kim Joung Soo;Kim Young Jin
    • Transactions of the Korean Society of Mechanical Engineers A
    • /
    • v.29 no.5 s.236
    • /
    • pp.754-761
    • /
    • 2005
  • The 40\% of wall thickness criterion which has been used as a plugging rule of steam generator tubes is applicable only to a single cracked tube. In the previous studies performed by authors, several global failure prediction models were introduced to estimate the failure loads of steam generator tubes containing two adjacent parallel axial through-wall cracks. These models were applied for thin plates with two parallel cracks and the COD base model was selected as the optimum one. The objective of this study is to verify the applicability of the proposed optimum global failure prediction model for real steam generator tubes with two parallel axial through-wall cracks. For the sake of this, a series of plastic collapse tests and finite element analyses have been carried out fur the steam generator tubes with two machined parallel axial through-wall cracks. Thereby, it was proven that the proposed optimum failure prediction model can be used as the best one to estimate the failure load quite well. Also, interaction effects between two adjacent cracks were assessed through additional finite element analyses to investigate the effect on the global failure behavior.

Development and application of a floor failure depth prediction system based on the WEKA platform

  • Lu, Yao;Bai, Liyang;Chen, Juntao;Tong, Weixin;Jiang, Zhe
    • Geomechanics and Engineering
    • /
    • v.23 no.1
    • /
    • pp.51-59
    • /
    • 2020
  • In this paper, the WEKA platform was used to mine and analyze measured data of floor failure depth and a prediction system of floor failure depth was developed with Java. Based on the standardization and discretization of 35-set measured data of floor failure depth in China, the grey correlation degree analysis on five factors affecting the floor failure depth was carried out. The correlation order from big to small is: mining depth, working face length, floor failure resistance, mining thickness, dip angle of coal seams. Naive Bayes model, neural network model and decision tree model were used for learning and training, and the accuracy of the confusion matrix, detailed accuracy and node error rate were analyzed. Finally, artificial neural network was concluded to be the optimal model. Based on Java language, a prediction system of floor failure depth was developed. With the easy operation in the system, the prediction from measured data and error analyses were performed for nine sets of data. The results show that the WEKA prediction formula has the smallest relative error and the best prediction effect. Besides, the applicability of WEKA prediction formula was analyzed. The results show that WEKA prediction has a better applicability under the coal seam mining depth of 110 m~550 m, dip angle of coal seams of 0°~15° and working face length of 30 m~135 m.

Plasticity Model Using Three Orthogonal Stress Components for Concrete in Compression (압축력을 받는 콘크리트에 대한 세 직교 응력 성분을 이용한 소성 모델)

  • Kim Jae-Yo;Park Hong-Gun
    • Journal of the Korea Concrete Institute
    • /
    • v.16 no.3 s.81
    • /
    • pp.345-356
    • /
    • 2004
  • A plasticity model was developed to predict the behavioral characteristics of concrete in multiaxial compression. To extend the applicability of the proposed model to concrete in various stress states, a new approach for failure criteria was attempted. A stress was decomposed into one volumetric and two deviatoric components orthogonal to each other. Three failure criteria wire provided independently for each stress component. To satisfy the three failure criteria, the plasticity model using multiple failure criteria was Implemented. Each failure surface was defined by equivalent volumetric or deviatoric plastic strain. To present dilatancy due to compressive damage a non-associative flow nile was proposed. The proposed model was implemented to finite element analysis, and it was verified by comparisons with various existing test results. The comparisons show that the proposed model predicted well most of the experiments by using three independent failure criteria.

Shear Capacity Curve Model for Circular RC Bridge Columns under Seismic Loads (지진하중을 받는 철근콘크리트 원형교각의 전단성능곡선 모델)

  • Lee, Jae-Hoon;Ko, Seong-Hyun;Chung, Young-Soo
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.10 no.2 s.48
    • /
    • pp.1-10
    • /
    • 2006
  • Reinforced concrete bridge columns with relatively small aspect ratio show flexure-shear behavior, which is flexural behavior at initial and medium displacement stages and shear failure at final stage. Since the columns with flexure-shear failure have lower ductility than those with flexural failure, shear capacity curve models shall be applied as well as flexural capacity curve in order to determine ultimate displacement for seismic design or performance evaluation. In this paper, a modified shear capacity curve model is proposed and compared with the other models such as the CALTRANS model, Aschheim et al.'s model, and Priestley et al.'s model. Four shear capacity curve models are applied to the 4 full scale circular bridge column test results and the accuracy of each model is discussed. It may not be fully adequate to drive a final decision from the application to the limited number of test results, however the proposed model provides the better prediction of failure mode and ultimate displacement than the other models for the selected column test results.

Infinite Failure NHPP Software Mixture Reliability Growth Model Base on Record Value Statistics (기록값 통계량에 기초한 무한고장 NHPP 소프트웨어 혼합 신뢰성장 모형에 관한 연구)

  • Kim, Hee-Cheul;Shin, Hyun-Cheul;Kim, Kyung-Soo
    • Convergence Security Journal
    • /
    • v.7 no.3
    • /
    • pp.51-60
    • /
    • 2007
  • Infinite failure NHPP models presented in the literature exhibit either constant, monotonic increasing or monotonic decreasing failure occurrence rates per fault. In this paper, exponential distribution and Rayleigh distribution model was reviewed, proposes the mixture reliability model, which made out efficiency substituted for situation for failure time Algorithm to estimate the parameters used to maximum likelihood estimator and bisection method, model selection based on SSE and Kolmogorov distance, for the sake of efficient model, was employed. Analysis of failure using S27 data set for the sake of proposing shape parameter of the mixture distribution was employed. This analysis of failure data compared with the mixture distribution model and the existing model(using arithmetic and Laplace trend tests, bias tests) is presented.

  • PDF