“…Failure factors in air transport are numerous in number. They include materials, such as a missed manufacturing defects, wear or fatigue of a component; human factors, such as bad judgment, fatigue of the crew, or a misinterpretation of instructions and light signals; and environmental factors such as ice and snow, foreign object debris and bird strikes [14] [16] [40] [41].…”
In aircraft project management, reliability and maintainability are fundamental for ensuring system safety, for optimizing the manufacturing process and for improving assembly/disassembly operations when maintenance actions are required. The inclusion of such requirements helps to minimize life cycle costs, augments the residual lifetime of aircraft and consequently increases customer satisfaction. While most papers published in the aircraft engineering literature are rather evasive or do not accurately describe the role of reliability and maintainability (RM) methods in early design phases, this paper elucidates the problem. This paper discusses various concepts such as design for reliability and risk assessment analysis for improving aircraft safety and reliability at the deployment stages. The article also focuses on how reliability prediction issues are addressed using various methods, tools and standards, such as failure modes and effect analysis, fault tree analysis and guidelines such as MIL-STD-217f and ARP4754. Finally, this paper demonstrates that reliability is crucial to consider in all phases of the life cycle of an aircraft.
“…Failure factors in air transport are numerous in number. They include materials, such as a missed manufacturing defects, wear or fatigue of a component; human factors, such as bad judgment, fatigue of the crew, or a misinterpretation of instructions and light signals; and environmental factors such as ice and snow, foreign object debris and bird strikes [14] [16] [40] [41].…”
In aircraft project management, reliability and maintainability are fundamental for ensuring system safety, for optimizing the manufacturing process and for improving assembly/disassembly operations when maintenance actions are required. The inclusion of such requirements helps to minimize life cycle costs, augments the residual lifetime of aircraft and consequently increases customer satisfaction. While most papers published in the aircraft engineering literature are rather evasive or do not accurately describe the role of reliability and maintainability (RM) methods in early design phases, this paper elucidates the problem. This paper discusses various concepts such as design for reliability and risk assessment analysis for improving aircraft safety and reliability at the deployment stages. The article also focuses on how reliability prediction issues are addressed using various methods, tools and standards, such as failure modes and effect analysis, fault tree analysis and guidelines such as MIL-STD-217f and ARP4754. Finally, this paper demonstrates that reliability is crucial to consider in all phases of the life cycle of an aircraft.
“…As the possibility of a structural failure increases with a decrease in z , the membership function μA~(z) should be a decreasing function of z . A semi-trapezoid shape 27 is used for the membership function, see Figure 1, and it is expressed as Figure 1.Membership function.…”
Section: Frameworkmentioning
confidence: 99%
“…In this approach, a fuzzy criterion, defined through bands of values, represents the uncertainties in the structure. Wong et al 27 established a Fourier series method to analyze the fuzzy reliability of a turbine blade of an aero-engine under a linear fuzzy safety state. As a high-speed train also presents fuzzy characteristics, it is necessary to introduce a fuzzy random reliability function into the crosswind stability analysis of a high-speed train.…”
The conventional crosswind stability analysis of high-speed trains is based on a deterministic approach with the final output being a characteristic wind curve (CWC). The CWC only provides the dividing line between the safe state and failure state of vehicles, thus it cannot be used to evaluate the overturning probability of vehicles subjected to strong winds. To overcome this shortcoming of the conventional CWC, a fuzzy stochastic approach is proposed that can make an effective assessment of the operational safety of high-speed trains exposed to stochastic winds. According to this methodology, the uncertain parameters existing in the system such as stochastic winds and aerodynamic coefficients are modelled as basic random variables, and the failure of the structure is considered as a fuzzy random event. An algorithm for computing the unsteady aerodynamic loads of high-speed trains exposed to stochastic winds is created and then the aerodynamic loads are applied to a dynamic model of the vehicle system in order to investigate the dynamic response. Importance sampling is used to conduct an analysis of the crosswind stability of high-speed trains based on fuzzy random reliability theory. This finally leads to the substitution of the conventional CWC by probabilistic characteristic wind curves (PCWCs). The conventional CWC is shown to be over-conservative, while the PCWCs can provide more significant reference for the safe operation of high-speed trains.
“…CM247LC is a well-known material for such application because of its excellent pitting resistance and superior mechanical properties under high thermal loads [8]. However, the manufacture of components with complex geometries from CM247LC and Inconel 718, too, is very challenging and cost prohibitive when traditional processing technologies are employed, due to their intrinsic limitations [9][10][11][12][13][14][15].…”
High-temperature alloys pose significant challenges in additive manufacturing. These materials have unique properties, such as high resistance to mechanical and chemical degradation when exposed to high temperatures. Furthermore, when these alloys are used to produce hybrid components with other similar alloys, investigating their surface integrity is critical because any residual stress can lead to early stage cracks and poor fatigue performance. In this research, a hybrid manufacturing approach is employed to produce components from difficult to weld alloys, i.e. CM247LC deposited on IN718 through a laser based direct energy deposition (L-DED) process. The surface integrity, mechanical properties and microstructure of such hybrid components is investigated, especially their welding/joint areas. Crack-free processing regimes were established to deposit CM247LC while mitigating the negative effects onto the microstructure of the Inconel substrate. Especially, the thermal gradients were managed to deliver crack free sections of CM247LC with good interface bonding, strength and fine microstructure. It is important to note that this is achieved without any significant preheating that contrasts with what is reported in other investigations so far. Furthermore, end-use hybrid blisks with deposited CM247LC blades onto Inconel 718 disks (HUB) were manufactured and then machined within a single processing set-up. The results show that the substrate thickness, the machining between the deposited layers and the final machining and heat-treatment play a role in reducing residual stresses. Ultimately, such hybrid manufacturing approach can be considered a new solution for producing such components and also for their subsequent repair.
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