Failure Model

The exponential distribution has proved to be a reasonable failure model for electronic equipment (8—13). Since the field of reUabiUty emerged, owing to problems encountered with military electronics during World War II, exponential distribution has had considerable attention and apphcation. However, like any failure model, it has limitations which should be well understood. 

Model Validity Probabilistic failure models cannot be verified. Physical phenomena are observed in experiments and used in model correlations, but models are, at best, approximations of specific accident conditions. 

BS 6143 1990 Part 2 - The Guide to the Economics of.Quality Prevention, Appraisal and Failure Model. London BSI. 

Boolean equations can be used to model any system the system s reliability is calculated by factoring the equations into cutsets and substituting the probabilities for component fai lure 1 lus can be done for either success or failure models. Working directly with equations is not e erv one s ctip of tea many individuals prefer graphical to mathematical methods. I hus, symbols and appearance of the methods differ but they must represent the same Boolean equation for them to be eqni valent. 

MSFM Multiple-Sequential Failure Model NUREG/CR-2211, 1981... 

Samanta, P. K. et al, Multiple-Sequential Failure Model Evaluation of and Procedures for Human Error Dependency, BNL May 1985. 

Guarro, S. and D. Okrent, 1984, P 456 The Logic Flowgraph A New Approach to Process Failure Modeling and Diagnosis for Disturbance Analysis Applications, Nucl. Technol. 67, p 348, December. 

Figure 3-49 Rosen s Tensile Failure Model (After Rosen [3-27])...

To properly use failure rate data, the engineer or risk analyst must have an understanding of failure rates, their origin and limitations. This chapter discusses the types and source of failure rate data, the failure model used in computations, the confidence, tolerance and uncertainties in the development of failure rates and taxonomies which can store the data and influence their derivation. 

A uniform definition of a failure and a method of classifying failures is essential if data from different sources are to be compared. The anatomy of a failure includes the initiating or root cause of a failure that is propagated by contributory causes and results in a failure mode—the effect by which a failure occurs or is observed. Modes include failure to operate, no output, failure to alarm on demand. The end result of a failure sequence is the failure effect, such as no fluid is pumped to the absorber, or a tank overflows. As discussed in Appendix A of IEEE Std. 500-1984, only the equipment failure mode is relevant for data that are needed in a CPQRA. The failure model used in this book is based upon those in the IEEE publication and IPRDS. ... 

Figure 3 Latent condition - active failure model of accident causation passing through...

Equations (8.32) and (8.33) describe what we call the normal or no failure operation of the system of interest. The problem of failure detection is concerned with the detection of abrupt changes in a system, as modeled in Eqs. (8.32) and (8.33). Changes in (8.33) will be referred to as sensor failures. The main task of failure detection and compensation design is to modify the normal mode configuration to add the capability of detecting abrupt changes and compensating for them. In order to do that, we need to formulate what is called the failure model system ... 

Finite element methods (FEM) are capable of incorporating complex variations in materia stresses in the time varying response. While these methods are widely available, they are quite complex and, in many cases, their use is not warranted due to uncertainties in blast load prediction. The dynamic material properties presented in this section can be used in FEM calculations however, the simplified response limits in the next section may not be suitable. Most FEM codes contain complex failure models which are better indicators of acceptable response. See Chapter 6, Dynamic Analysis Methods, for additional information. 

As X is connected with Y, a failure of X will possibly affect the behaviour of Y. We identified and classified possible patterns of failure related to the co-operation of X and Y and called them failure modeling patterns. 

K. Matous et al Multiscale cohesive failure modeling of heterogeneous adhesives. J. Mech. Phys. Solids 56, 1511 (2008)... 

Classification of each of the many basic causes, according to the aforementioned system failure model ... 

The investigation of failures of manufactured components and systems, especially in the electronics and aerospace industries, has generated a variety of statistical models on which data analysis may be based. Each model uses a specific distibution of failure probabilities, and it is important to select a model that matches the actual distribution inherent in the product concerned. In the case of dielectric breakdown, where a large number of quite different modes of failure are known to occur, sometimes even together, the application of a particular statistical failure model must be approached with great caution. Nevertheless, one treatment, based on a Weibull distribution of failure probability, has taken root, and is most generally used in practice. For a dielectric, the Weibull failure probability function has the form... 

Figure 4.26 Compressive failure models in high-petformance fibers (a) micro-buckling model and (b) misorientation model (after Kozey and Kumai 1994).

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