Computational Models to Predict the Structural Reliability of Aerospace Systems

Three case studies are presented in which computational-based methodologies have been used to assess structural reliability in the aerospace industry. The studies involve hot section turbine disks of a helicopter engine, fan blades of a commercial airline engine and bearings in an auxiliary power unit. In all cases, the results of the computational models were used to support the certification process for design and application changes. The statistical variation in design and usage parameters including geometry, materials, speed, temperature and other environmental factors are considered. The response surface approach was used to construct a durability performance function. This performance function is used with the first order reliability method (FORM) to determine the probability of failure and the sensitivity of the failure to the design and usage parameters. A hybrid combination of perturbation analysis and Monte Carlo simulation is used to incorporate time dependent random variables. System reliability is used to determine the system probability of failure, and the sensitivity of the system durability to the design and usage parameters.

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Efficient Reliability Assessment With the Conditional Probability Method

Journal of Mechanical Design ◽

10.1115/1.4040170 ◽

2018 ◽

Vol 140 (8) ◽

Cited By ~ 4

Author(s):

Rami Mansour ◽

Mårten Olsson

Keyword(s):

Conditional Probability ◽

Structural Reliability ◽

A Priori ◽

Reliability Assessment ◽

Probability Of Failure ◽

Assessment Method ◽

Probability Method ◽

Probability Of Survival ◽

Design Variables ◽

Reliability Method

Reliability assessment is an important procedure in engineering design in which the probability of failure or equivalently the probability of survival is computed based on appropriate design criteria and model behavior. In this paper, a new approximate and efficient reliability assessment method is proposed: the conditional probability method (CPM). Focus is set on computational efficiency and the proposed method is applied to classical load-strength structural reliability problems. The core of the approach is in the computation of the probability of failure starting from the conditional probability of failure given the load. The number of function evaluations to compute the probability of failure is a priori known to be 3n + 2 in CPM, where n is the number of stochastic design variables excluding the strength. The necessary number of function evaluations for the reliability assessment, which may correspond to expensive computations, is therefore substantially lower in CPM than in the existing structural reliability methods such as the widely used first-order reliability method (FORM).

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System Reliability of Existing Jacket Platform in Malaysian Water (Failure Path and System Reliability Index)

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.567.307 ◽

2014 ◽

Vol 567 ◽

pp. 307-312 ◽

Cited By ~ 1

Author(s):

V. John Kurian ◽

Mohamed Mubarak Abdul Wahab ◽

T.S. Kheang ◽

Mohd Shahir Liew

Keyword(s):

System Reliability ◽

Reliability Index ◽

Structural Reliability ◽

Pushover Analysis ◽

Probability Of Failure ◽

Jacket Platform ◽

First Order ◽

Failure Path ◽

Reliability Method ◽

Two Parameters

The objective of this work is to determine the structural reliability of an existing jacket platform in Malaysia, by determining the system probability of failure and its corresponding reliability index. These two parameters are important indicators for assessing the integrity and reliability of the platform, and will point out whether the platform is suitable for continued operation. In this study, pushover analysis is used to determine possible failure paths of the structure, while First Order Reliability Method (FORM) and Simple Bound Formula are used to determine the failure probability and reliability index. Three failure paths of the platform are established. The reliability index of these paths is found with the highest Reliability Indexto be 18.82 from the 315-degree path, while the system reliability index is 9.23. This illustrates that the platform is robust and the chances of collapse is very small.

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Performance of In-Line Inspection Tools and Their Influence on the Structural Reliability of Corroded Pipeline

Volume 2: Integrity Management; Poster Session; Student Paper Competition ◽

10.1115/ipc2006-10594 ◽

2006 ◽

Author(s):

Jose´ de Jesu´s Leal Carvajalino ◽

Fa´bio de Castro Marangone ◽

Jose´ Luiz de Franc¸a Freire

Keyword(s):

Sequential Analysis ◽

Structural Reliability ◽

Field Measurements ◽

Visual Basic ◽

Probability Of Failure ◽

First Order ◽

Reliability Method ◽

Minimum Number ◽

Corrosion Defects ◽

Reference Tool

This paper presents: i) the assessment of in-line inspection (ILI) tools’ performance in the measurement of defects caused by corrosion; ii) different methods for calculating the probability of failure (POF) of corroded pipeline based on the ILI report. The ILI report is compared to the geometry of defects measured by a reference tool (field measurements) and the errors associated with each measurement system are analyzed and assessed through different statistical methods. The minimum number of field measurements necessary to verify the performance of the ILI in sizing the corrosion defects is determined by implementing a test based on sequential analysis. The POF of a pipeline is calculated using two methods: i) first order reliability method (FORM) and ii) propagation of uncertainties. The comparison between calculated and acceptable POF enables the determining of the next reinspection period. When the calculated POF exceeds the acceptable POF before completing the amount of time desired for the next inspection, the developed procedure enables determining the number of repairs that must be made to reach the desired time when the next ILI will be performed. Finally, a software in Visual Basic® language was developed to implement this work.

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Iteration Algorithm for Propagation of Mixed Uncertainties in Reliability Analysis

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.199-200.569 ◽

2011 ◽

Vol 199-200 ◽

pp. 569-574

Author(s):

Chang Cong Zhou ◽

Zhen Zhou Lu ◽

Qi Wang

Keyword(s):

Structural Reliability ◽

Random Variables ◽

Point Estimate ◽

Iteration Algorithm ◽

Fourth Moment ◽

Performance Function ◽

Fuzzy Variables ◽

Point Estimate Method ◽

Interval Variables ◽

Reliability Method

For structural reliability problems simultaneously involving random variables, interval variables and fuzzy variables, an iteration algorithm is proposed to deal with the propagation of uncertainties. Corresponding to assumed membership value in the membership level interval [0,1], the membership interval of fuzzy variables can be obtained. After the fuzzy variables and the interval variables’ effects on the extreme value of performance function are alternately and iteratively analyzed with the random variables’ effects on statistical properties of the performance function, converged design point can be calculated, and the reliability can be as well calculated by the fourth moment algorithm based on the point estimate method. Finally the membership function of the reliability can be solved. Owing to the faster convergence of the iteration algorithm, the efficiency of the proposed algorithm is highly improved compared to the conventional numerical simulation method. And the adoption of fourth moment method proves much better in accuracy than only applying first order reliability method in the iteration algorithm. After the basic concept and process of the proposed algorithm is detailed, several numerical and engineering examples are studied to demonstrate its advantage both in efficiency and accuracy.

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METAMODEL-BASED PROBABILISTIC DESIGN OPTIMIZATION OF STATIC SYSTEMS WITH AN EXTENSION TO DYNAMIC SYSTEMS

International Journal of Reliability Quality and Safety Engineering ◽

10.1142/s0218539311004263 ◽

2011 ◽

Vol 18 (04) ◽

pp. 305-326 ◽

Cited By ~ 2

Author(s):

TURUNA S. SEECHARAN ◽

GORDON J. SAVAGE

Keyword(s):

Structural Reliability ◽

Mechanistic Model ◽

Complex Form ◽

Probability Of Failure ◽

Performance Measure ◽

Surface Model ◽

Probabilistic Design ◽

Design Variables ◽

Reliability Method ◽

Distribution Parameters

In design, much research deals with cases where design variables are deterministic thus ignoring possible uncertainties present in manufacturing or environmental conditions. When uncertainty is considered, the design variables follow a particular distribution whose parameters are defined. Probabilistic design aims to reduce the probability of failure of a system by moving the distribution parameters of the design variables. The most popular method to estimate the probability of failure is a Monte Carlo Simulation where, using the distribution parameters, many runs are generated and the number of times the system does not meet specifications is counted. This method, however, can become time-consuming as the mechanistic model developed to model a physical system becomes increasingly complex. From structural reliability theory, the First Order Reliability Method (FORM) is an efficient method to estimate probability and efficiently moves the parameters to reduce failure probability. However, if the mechanistic model is too complex FORM becomes difficult to use. This paper presents a methodology to use approximating functions, called 'metamodels', with FORM to search for a design that minimizes the probability of failure. The method will be applied to three examples and the accuracy and speed of this metamodel-based probabilistic design method will be discussed. The speed and accuracy of three popular metamodels, the response surface model, the Radial Basis Function and the Kriging model are compared. Later, some theory will be presented on how the method can be applied to systems with a dynamic performance measure where the response lifetime is required to computer another performance measure.

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Schedule Planning and Maintenance Activities Auxiliary Power Unit (APU) Boeing 737-500 Aircraft With Reliability Method

Prosiding Seminar Nasional Sains Teknologi dan Inovasi Indonesia (SENASTINDO) ◽

10.54706/senastindo.v3.2021.130 ◽

2021 ◽

Vol 3 ◽

pp. 91-102

Author(s):

Ferry Setiawan ◽

Yustina Titin Purwantiningsih ◽

Dhimas Wicaksono

Keyword(s):

Power Unit ◽

Lubrication System ◽

Reliability Parameter ◽

Electrical System ◽

Ignition System ◽

Auxiliary Power Unit ◽

Auxiliary Power ◽

Reliability Method ◽

Mode Effect ◽

Maintenance Activities

Penelitian ini bertujuan untuk merencanakan jadwal dan aktifitas maintenance yang yangefektif pada sistem auxiliary power unit sehingga tidak terjadi lagi kegagalan ataupun kerusakan yang tidak di rencanakan atau terjadi secara tiba – tiba. Kegagalan pada peralatan auxiliary power unit ada sering terjadi pada beberapa sistem kerja yaitu electrical system, Lubrication System dan Ignition System, di mana hal ini menimbulkan kerugian yang cukup besar bagi perusahaan penerbangan. Metode penelitian ini menggunakan pendekatan kualitatif dan kuantitatif, analisis kualitatif menggunakan metode Failure Mode Effect and Critically Analysis (FMECA) dengan menganalisis faktor – faktor penyebab kegagalan dan efek terjadinya kegagalan, dengan hasil penyebab kegagalan pada beberapa sitem kerja auxiliary power unit (APU) adalah sebagai berikut electrical system adalah pada komponen start Relay, Lubrication System adalah pada komponen Oil Filter, Ignition System adalah pada igniter plug. Dari hasil analisis FMECA tersebut di lakukan analisis kuantitatif dengan analisis dilakukan menggunakan metode reliability, parameter kehandalan dihitung dengan probabilitas distribusi Weibull, untuk menentukan batas kritis waktu operasional komponen ataupun part sistem yang merupakan batas kehandalan suatu sistem auxiliary power unit. Batas kritis operasional electrical system adalah sebesar 434 jam terbang, lubrication system adalah 1186 jam terbang, dan Ignition system adalah sebesar 1610 jam terbang, selanjutnya hasil tersebut di gunakan untuk menentukan jadwal maintenance yang efektif di dukung dengan perencanaan aktifitas maintenance yang tepat untuk menghilangkan penyebab – penyebab kegagalan pada peralalatan auxiliary power unit.

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An Assessment for Structural Reliability of Offshore Risers due to Probability of Fatigue Failure

2010 8th International Pipeline Conference, Volume 4 ◽

10.1115/ipc2010-31587 ◽

2010 ◽

Author(s):

Celso K. Morooka ◽

Wania Stefane ◽

Cyntia G. C. Matt ◽

Ricardo Franciss ◽

Leandro Basilio

Keyword(s):

Fatigue Failure ◽

Structural Reliability ◽

Failure Process ◽

Probability Of Failure ◽

Structure Design ◽

Manufacture Process ◽

First Case ◽

Reliability Method ◽

Steel Catenary Risers ◽

Offshore Risers

Different configurations for riser systems have been emerged as suitable technological and economical solutions for offshore petroleum fields in ultra deep water. The study and development of methodologies for riser project considering the uncertainties involved in the manufacture process of offshore risers and effects of meteocean conditions, such as waves, current and platform motions for the fatigue failure is fundamental to increase the reliability of riser structure design. The present work presents a procedure to evaluate the probability of fatigue failure in offshore Steel Catenary Risers (SCR) identifying the influence of the main parameters in the failure process due to fatigue. Meteocean conditions and uncertainties due to accumulated fatigue damage given by Miner-Palmgren’s rule are here considered. The probabilistic methodology is taken into account, and the analytical approach based on the First Order Reliability Method (FORM) is applied considering two practical cases. In the first case, calculations are performed to compare with the results from the literature, and the second one calculation is carried out considering a typical Brazilian offshore field operation. In the calculations, results for the probability of failure, as well as, the riser service life are observed in four different locations along the SCR length. Finally, conclusions are shown to the probability of failure due to fatigue such as influence of each parameter in the process.

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Probabilistic framework for the assessment of the flexural design of concrete sleepers

Proceedings of the Institution of Mechanical Engineers Part F Journal of Rail and Rapid Transit ◽

10.1177/0954409719854569 ◽

2019 ◽

Vol 234 (7) ◽

pp. 691-701 ◽

Cited By ~ 3

Author(s):

Alvaro E Canga Ruiz ◽

J Riley Edwards ◽

Yu Qian ◽

Marcus S Dersch

Keyword(s):

Cross Sections ◽

Structural Reliability ◽

Failure Modes ◽

Limit State ◽

Probability Of Failure ◽

Extensive Study ◽

Light Rail ◽

Demand Model ◽

Reliability Method ◽

Current Design

An extensive study of the flexural performance of monoblock prestressed concrete sleepers in a light rail system was conducted as part of a research program funded by the Federal Transit Administration. Five consecutive sleepers deployed on the track were instrumented with strain gauges at their critical design cross-sections (center and rail seats) to obtain relevant flexural information during an uninterrupted period of 14 months. Results were compared with the projected design capacities obtained from the application of current design standards, resulting in glaring differences. The current design methodologies were deemed insufficient for the development of optimal design solutions for light rail applications. Furthermore, structural reliability analysis is employed to study the flexural capacity of the sleeper design. A capacity model based on the material and geometric properties of the sleeper design was developed. The demand model was derived from the field flexural data of over 27,000 train passes, fitting this information to predefined probability distributions. Four limit-state functions were defined to represent the typical flexural failure modes. The probability of failure was calculated using first-order reliability method, second-order reliability method, and Monte Carlo simulation. Ultimately, the analysis yielded consistent results for the three methods, showing largely low probability of failure at both design cross-sections under the studied demand level. In conclusion, the sleeper's capacity was higher than the existing field demands, indicating an overly conservative design approach.

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