دانلود رایگان مقاله لاتین قابلیت اطمینان تیغه هلیکوپتر از سایت الزویر
عنوان فارسی مقاله:
قابلیت اطمینان تیغه هلیکوپتر: تجزیه و تحلیل اطلاعات آماری و مدل سازی
عنوان انگلیسی مقاله:
Helicopter blade reliability: Statistical data analysis and modeling
سال انتشار : 2016
مقدمه انگلیسی مقاله:
The growing trends of the application of the concept of reliability in mechanical engineering design owe to the statistical nature of the various failure modes of the mechanical components. It is essential that the mechanical equipment operate reliably under all the conditions in which it is used; however, the requirement for reliability is different for each application. Reliability is the probability that a component, equipment, or system will perform a required function under the operating conditions encountered for a stated period of time . There are many different operational requirements and various environments, thus reliability is quantified in many different ways. One of them is the statistical analysis that is referred to as lifetime, survival time, or failure time data. Some methods of dealing with lifetime data are quite old, but starting at about 1970 the field expanded rapidly with respect to methodology, theory, and fields of applications . Limited failure data and statistical analyses of helicopter components reliability exist in the technical literature and few statistical studies were made to model the reliability of these parts. BellHelicopters Company documented the reliability for some OH-58D components using the strength/load interaction formulation and established a life versus reliability relationship . Sometimes there is a single lifetime for each individual, but failure may be of different modes of types. Often the modes refer to cause of failure, in which case the term “competing risks” or “multiple modes of failure” is sometimes used . There have been many efforts to consider failure mechanisms (competing risks) for each component to analyze reliability [4–6]. Kaplan and Meier  presented the Kaplan–Meier estimator for calculating the nonparametric reliability function. In the nonparametric analysis, the confidence intervals are derived to inform about the dispersion around the nonparametric reliability function [8,9]. Nelson and Aalen presented the Nelson–Aalen estimator for calculating the cumulative modespecific functions for each failure modes [10–13]. In this paper, failure data are collected for 338 helicopter blades. These blades have 41 different failure modes. Two different strategies are adopted. In the first one, general failure is defined as scrapping of the blade, which results in retirement of the blade. A nonparametric analysis of blade reliability is conducted for 338 blades, which were in service between 1974 and 2012. Because in this case the dataset is censored due to the fact that some of the blades are still operational at the end of gathering data, the Kaplan–Meier estimator is used for calculating the blade reliability function. In addition, confidence intervals are derived for the nonparametric reliability result. In the second strategy, the blade isassumed to be subjected to different modes of failure. In the other words, causes other than scrapping such as fatigue, excessive vibration, corrosion, . . . can also make the blade to fail. So, the blade is faced with multiple modes of failure in this strategy. In this case, the dataset is unsensored because the first time failures of the blades are available. A nonparametric analysis of blade reliability is conducted using the Kaplan–Meier estimator  and the confi- dence intervals are derived for the nonparametric reliability result. In addition, the cumulative mode-specific functions are derived for each failure modes by using Nelson–Aalen estimator. In both cases, parametric fits are conducted using the maximum likelihood estimation (MLE) and graphical approach. Moreover, the goodness of fit tests are used to justify the choice of a 3-parameter Weibull distribution for modeling blade reliability and then with the maximum likelihood estimation, the parameters of the 3-parameter Weibull distribution are calculated.
Handbook of Case Histories in Failure Analysis, Volume 1: https://books.google.com/books?isbn=0871704536 Khlefa Alarbe Esaklul - 1992 - Technology & Engineering Failure of a Helicopter Main Rotor Blade Lawrence Kashar, Kashar Technical ... that it was not defective and had not given a false indication of blade reliability. The Evolution of the Rotor Blade: A review of helicopter blade ... www.emeraldinsight.com/doi/pdf/10.1108/eb034529 by WN Twelvetrees - 1969 The Evolution of the Rotor Blade: A review of helicopter blade construction with a survey of possible future developments in this field. Article Options and Tools ... [PDF]Helicopter Structures - A Review of Loads, Fatigue Design Techniques ... dtic.mil/dtic/tr/fulltext/u2/a267115.pdf by DC LOMBARDO - 1993 - Cited by 21 - Related articles May 15, 1993 - 5. Comparison of the lift produced by a rotor blade for two different helicopter 10 flight speeds. Lift is shown only at the 95% blade radial station. Testing for Rotor Reliability - Rotor & Wing www.rotorandwing.com/2010/05/01/testing-for-rotor-reliability/ May 1, 2010 - Helicopter rotor blades are highly sophisticated products, consisting of a ... testing systems that can test with greater reliability and efficiency. Why Things Fail: From Tires to Helicopter Blades, Everything Breaks ... https://www.wired.com/2012/10/ff-why-products-fail/ Oct 19, 2012 - From tires to hinges to helicopter blades, everything breaks eventually. ... Officially, Building 4 is about reliability, but it's actually more about ... E-flite's Blade SR RC Helicopter Review - RC Helicopter Fun www.rchelicopterfun.com/blade-sr.html When I first heard the rumors about the Blade SR (single rotor) helicopter, I have to admit, I got pretty excited. I heard it was going to be a 300 size bird and ...