A Damage Tolerance Approach for Management of Aging Gas Turbine Engines

Cowie, W.

doi:10.1007/978-3-642-84364-8_7

Cited by 4 publications

(2 citation statements)

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“…(4). Song and Bae27 also showed that crack length and crack propagation rate were related by a first order model as have Cowie,28 Dawicke …”

Section: Modeling Damage Initiationmentioning

confidence: 92%

<title>Nonlinear damage models for diagnosis and prognosis in structural dynamic systems</title>

Adams

2002

SPIE Proceedings

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This work aims to establish a nonlinear dynamics framework for diagnosis and prognosis in structural dynamic systems. The objective is to develop an analytically sound means for extracting features, which can be used to characterize damage, from modal-based input-output data in complex hybrid structures with heterogeneous materials and many components. Although systems like this are complex in nature, the premise of the work here is that damage initiates and evolves in the same phenomenological way regardless of the physical system according to nonlinear dynamic processes. That is, bifurcations occur in healthy systems as a result of damage.By projecting a priori the equations of motion of high-dimensional structural dynamic systems onto lower dimensional center, or so-called 'damage', manifolds, it is demonstrated that model reduction near bifurcations might be a useful way to identify certain features in the input-output data that are helpful in identifying damage.Normal forms describing local co-dimension one and two bifurcations (e.g. transcritical, subcritical pitchfork, and asymmetric pitchfork bifurcations) are assumed to govern the initiation and evolution of damage in a loworder model. Real-world complications in damage prognosis involving spatial bifurcations, global bifurcation phenomena, and the sensitivity of damage to small changes in initial conditions are also briefly discussed.

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“…(4). Song and Bae27 also showed that crack length and crack propagation rate were related by a first order model as have Cowie,28 Dawicke …”

Section: Modeling Damage Initiationmentioning

confidence: 92%

<title>Nonlinear damage models for diagnosis and prognosis in structural dynamic systems</title>

Adams

2002

SPIE Proceedings

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“…In recent years there has been growing interest in the damage tolerance approach to life prediction where the growth of a crack which has passed undetected after inspection, is calculated, but is prevented from becoming catastrophic by nondestructive evaluation (NDE) and preventive maintenance. Much of this interest has been prompted by the success of the US Air Force ASIP and ENSIP programs mandating the damage tolerance approach to the life management of military airframes and engines [3]. These programs have established damage tolerance as an integral part of engine design and have also resulted in the generation of NDE probability of detection data and in the implementation of advanced NDE techniques.…”

Section: Introductionmentioning

confidence: 99%

A Simple Reliability Model for the Fatigue Failure of Repairable Offshore Structures

Connolly

Hudak

1993

Fatigue Fract Eng Mat Struct

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A simple reliability model for fatigue failure of tubular welded joints used in the construction of offshore oil and gas platforms is proposed. The stress-life data obtained from large-scale fatigue tests conducted o n tubular joints is used as the starting point in the analysis and is combined with a fracture mechanics model to estimate the distribution of initial defect sizes. This initial defect distribution is hypothetical but it agrees well with other initial defect distributions quoted in the literature and when used with the fracture mechanics model results in failure probabilities identical to those obtained from the stress-life data. This calculated distribution of initial defect sizes is modified as a result of crack growth under cyclic loading and the probability of failure as a function of fatigue cycles is calculated. The failure probability is modified by inspection, and repair and the results illustrate the trade-off between inspection sensitivity and inspection interval for any desired reliability. NOMENCLATURE A S = hot spot stress range a, = initial defect depth AK = stress intensity factor range da/dN = crack growth rate a,= final crack depth N = no. of fatigue cycles (T = standard deviation of fatigue lives p = mean of fatigue lives Lnl,(a,) = probability density function for initial defect depth C, m =constants in crack growth law f(a,) = probability density function for crack depth at N cycles PODfa) = probability of detecting crack of depth a a(90) = crack depth corresponding to 90% POD a, = crack depth at N cycles j = no. of inspections i = current inspection a,k = depth of crack at kth inspection which was introduced by repair at the ith inspection f;,(a,) = distribution for repaired portion of the total crack density function that was repaired at inspection i f(a,= -,) = probability density function for crack sizes just before the ith inspection a n = , = crack depth at ith inspection

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A nonlinear dynamical systems framework for structural diagnosis and prognosis

Adams

Nataraju

2002

International Journal of Engineering Science

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A Damage Tolerance Approach for Management of Aging Gas Turbine Engines

Cited by 4 publications

References 1 publication

<title>Nonlinear damage models for diagnosis and prognosis in structural dynamic systems</title>

<title>Nonlinear damage models for diagnosis and prognosis in structural dynamic systems</title>

A Simple Reliability Model for the Fatigue Failure of Repairable Offshore Structures

A nonlinear dynamical systems framework for structural diagnosis and prognosis

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