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Mechanical reliability analysis using stress-strength interference model and engineering application of reliability: system safety assessment

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2019
Sarıgül, Murat Barış
Mechanical reliability is the main concern of this thesis. Reliability prediction of mechanical components is commonly performed via four different techniques which are Component Failure Data Analysis, Empirical Reliability Analysis, Stress-Strength Interference Model and Reliability Database and Handbook Usage. However, Stress Strength Reliability Model, which has a great popularity in these reliability estimation methods in literature, is the main focus of this research. Five methods are used in calculations modeled with Stress-Strength Interference. These are analytical methods, which are First Order Reliability Method (FORM), Second Order Reliability Method (SORM), and simulation methods, which are Monte Carlo Simulation (MCS), Importance Sampling (IS), Adaptive Kriging Monte Carlo Simulation (AK-MCS). Landing Gear Emergency Extension System is taken into account and analyzed in details. Venting valve, which is a part of this subsystem, is chosen as an example of mechanical component. While stress random variables of the venting valve are assumed to be uniformly distributed, strength random variables are considered as both normal and lognormal random variables in calculations. Five different reliability methods are performed in this manner and results are compared extensively. Number of evaluation is also assessed as an indication of the strength of the method. System safety assessment is an application area of reliability values. “SAE ARP 4761 Aerospace Recommended Practice” defines the process of safety assessment of the systems. A reliability requirement for venting valve is created in this manner and an example of validation is performed which shows the relation between system safety engineering and reliability engineering disciplines.