Probabilistic Methods for Design Assessment of Reliability with Inspection

Wu, Y.-T.; Enright, Michael P.; Millwater, Harry

doi:10.2514/2.1730

Cited by 80 publications

(38 citation statements)

References 3 publications

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“…The perturbation size must be large enough to evoke a significant enough change in the computed POF relative to the unperturbed analysis. We note that it is exceedingly laborious to obtain finite difference estimates in that a very large number of Monte Carlo samples must be used in order to prevent the difference in the POF from being masked by sampling variance, or a very refined importance sampling method must be used [1,29]. In addition, a separate analysis must be performed for each sensitivity estimate.…”

Section: ∂P ∂θmentioning

confidence: 99%

“…The industry working group concluded that additional enhancements to the conventional rotor life management methodology could be established which explicitly address anomalous conditions. Henceforth, the FAA, industry, and research partners have been proactively developing the methodology [1][2][3], computer software [4,5], and necessary data to quantify and hence mitigate the probabilityof-fracture (POF) of gas turbine engine rotor disks.…”

Section: Introductionmentioning

confidence: 99%

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Probabilistic Sensitivities for Fatigue Analysis of Turbine Engine Disks

Millwater

Osborn

2006

International Journal of Rotating Machinery

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A methodology is developed and applied that determines the sensitivities of the probability-of-fracture of a gas turbine disk fatigue analysis with respect to the parameters of the probability distributions describing the random variables. The disk material is subject to initial anomalies, in either low-or high-frequency quantities, such that commonly used materials (titanium, nickel, powder nickel) and common damage mechanisms (inherent defects or surface damage) can be considered. The derivation is developed for Monte Carlo sampling such that the existing failure samples are used and the sensitivities are obtained with minimal additional computational time. Variance estimates and confidence bounds of the sensitivity estimates are developed. The methodology is demonstrated and verified using a multizone probabilistic fatigue analysis of a gas turbine compressor disk analysis considering stress scatter, crack growth propagation scatter, and initial crack size as random variables.

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Section: ∂P ∂θmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Probabilistic Sensitivities for Fatigue Analysis of Turbine Engine Disks

Millwater

Osborn

2006

International Journal of Rotating Machinery

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“…A "zone-based" system reliability methodology is used in DARWIN TM to compute the probability-of-fracture of a disk as a function of flight cycles [5,6]. This methodology accounts for: ß the probability of having an anomaly in the disk, ß the possibility that a hard alpha anomaly developed during the titanium melt process could be in any location of the disk, ß the initial size distribution of the anomaly, ß randomness in the time of inspection time, probability of detection, finite element stresses and fracture mechanics analysis, ß the probability-of-fracture if an anomaly exists, ß the probability of detecting an anomaly and removing a disk before the disk has fractured.…”

Section: Figure 1 Interaction Of the Darwin Tm Componentsmentioning

confidence: 99%

Application of an XML-based Database for Probabilistic Analysis

Millwater¹,

Fitch²,

Enright³

et al. 2003

44th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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The Extensible Markup Language, XML, is used as database file format for a probabilistic fracture mechanics program, DARWIN ™ , which is used for risk assessment of commercial aircraft engine rotors. The database is used for storage and retrieval of probabilistic results during computations, for transferring data from the computational code to the graphical user interface, generating HTML output reports, and for archiving the results. The advantages of using an XML database file format are discussed through an application example.

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“…13-15, among many others). Over the past several years, a number of methods have been developed to improve the efficiency of zone-based system reliability predictions, such as tailored response surface 16 , zone refinement 17 , importance sampling 16,18 , and parallel processing 19 , among other improvements. In this paper, a methodology is presented for variance reduction of sampling-based series system reliability predictions based on optimal allocation of Monte Carlo samples to the individual failure modes.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Optimal Sampling Methodology for Zone-Based Probabilistic Life Prediction

Enright

Millwater²,

Huyse

2004

45th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics &Amp;amp; Materials Conference

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Simulation-based system reliability prediction may require significant computations, particularly when the expected value of the system failure probability is relatively low. In this paper, a methodology is presented for variance reduction of sampling-based series system reliability predictions based on optimal allocation of Monte Carlo samples to the individual failure modes. An algorithm is presented for adaptively allocating samples to member failure modes based on initial estimates of the member failure probabilities p i . The methodology is demonstrated for a simple series system and a gas turbine engine disk modeled using a zone-based series system approach. For the example considered, it is shown that the computational accuracy of the method does not appear to depend on the initial p i estimate. However, the computational efficiency is highly dependent on the initial p i estimate. The results can be applied to improve the efficiency of sampling-based series system reliability predictions. Nomenclature COV i= coefficient of variation of the failure probability for member i E (•) = mean value g = limit state function i, j = member number = standard deviation of the failure probability for member i.

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Probabilistic Methods for Design Assessment of Reliability with Inspection

Cited by 80 publications

References 3 publications

Probabilistic Sensitivities for Fatigue Analysis of Turbine Engine Disks

Probabilistic Sensitivities for Fatigue Analysis of Turbine Engine Disks

Application of an XML-based Database for Probabilistic Analysis

Adaptive Optimal Sampling Methodology for Zone-Based Probabilistic Life Prediction

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