本文關(guān)鍵詞：基于可靠性的民用飛機計劃維修的決策方法　出處：《南京航空航天大學》2016年博士論文　論文類型：學位論文

  更多相關(guān)文章： 可靠性評估 可靠性折算 環(huán)境因子 截尾數(shù)據(jù) 小樣本 分段分布 計劃維修 維修決策 聚類 單純形

【摘要】：維修是保證民用飛機持續(xù)適航的重要手段,故在飛機設(shè)計、制造和運營的整個過程中,維修都是必須重點關(guān)注。例如,在民用飛機設(shè)計制造時就開始編制維修大綱、維修手冊等,在飛機運用中又必須實施維修活動、記錄維修信息。合理的維修降低維修成本不僅可以為飛機制造商贏得市場而且還能為航空公司節(jié)約成本,因此維修是飛機的重要保障性工作。本文主要從可靠性評估、維修策略和維修任務(wù)組合優(yōu)化三個角度討論了民用飛機的維修。首先,準確的可靠性評估是民用飛機維修決策的基礎(chǔ),沒有準確的可靠性信息很難對維修做出正確的評判。維修策略是根據(jù)維修項目的可靠性、特點和需要確定每個維修項目合理的維修方式。最后,在實際執(zhí)行維修活動時,往往還要對維修任務(wù)進行優(yōu)化組合形成維修工作包,這不僅是組織管理維修活動的需要,而且還能降低維修成本。民用飛機使用過程中經(jīng)常產(chǎn)生各種截尾小樣本,這增加了可靠性評估的困難。鑒于截尾樣本的真實壽命與完全樣本有相同的分布,若把截尾樣本轉(zhuǎn)化成完全樣本,則可按照完全樣本的頻數(shù)的比例估算截尾樣本折算的頻數(shù)。一方面在該頻數(shù)的基礎(chǔ)上改進了標準壽命表估計和乘積限估計,使得它們能準確地估計各類截尾樣本。另一方面,把該頻數(shù)作為權(quán)重因素之一,并結(jié)合順序統(tǒng)計量在標準分布下的方差,形成能精確估計各類截尾樣本的加權(quán)最小二乘法。由于截尾數(shù)據(jù)的似然函數(shù)中含有概率分布函數(shù)而導致MLE性能下降,本文在構(gòu)造截尾事件及其概率密度函數(shù)的基礎(chǔ)上,形成了截尾數(shù)據(jù)的概率密度函數(shù)。用截尾數(shù)據(jù)的概率密度函數(shù)替代傳統(tǒng)MLE使用的概率分布函數(shù),再與完全樣本的概率密度函數(shù)共同構(gòu)造似然函數(shù)。這樣似然函數(shù)就全部由概率密度函數(shù)組成,故改進的MLE符合MLE定義的。大量的仿真實驗證明本文改進的方法可以很好評估截尾小樣本的可靠度,比傳統(tǒng)MLE估計得更加準確。尤其是當樣本中截尾數(shù)據(jù)的比例比較高的情況下,本文改進方法的優(yōu)勢更加明顯。從評估升降舵作動器和副翼作動器的可靠性的實例中可以看出,和傳統(tǒng)方法相比,本文改進方法評估的可靠性傾向于保守而且更加精確。通常在衡量民機可靠性時,都假設(shè)在整個壽命周期內(nèi)風險有相同的規(guī)律并且故障服從同一個分布,故在整個壽命周期內(nèi)使用統(tǒng)一的可靠度模型。事實上,民用飛機中許多設(shè)備的故障風險都很復雜,往往隨運行時間有不同的特點甚至呈現(xiàn)多峰性,例如浴盆曲線,因此在整個壽命周期內(nèi)用單一模型擬合設(shè)備可靠度的方法往往有較大的誤差。如果根據(jù)風險變化的特點把整個壽命周期分成不同的區(qū)間,則分段擬合就可以更準確地逼近可靠度的變化。故本文把風險當作分段函數(shù),提出了兩類分段可靠度分布:一類風險函數(shù)是連續(xù)的;另一類風險函數(shù)可以是間斷的。為了估計分段可靠度模型的參數(shù),在對壽命樣本進行聚類的基礎(chǔ)上,本文討論了分段可靠度分布的回歸估計和極大似然估計。最后,因為通常的信息準則不適合分段分布模型,本文改進了信息準則以評價分段可靠度模型的優(yōu)劣。經(jīng)過大量的實驗和仿真驗證,本文的分段可靠度模型和它的估計方法比傳統(tǒng)的單一模型更精確,尤其是在風險具有階段性和多峰性時。分段風險模型在評估發(fā)動機引氣系統(tǒng)和前緣襟翼接近傳感器的可靠度中表現(xiàn)良好,說明了分段可靠度模型有很好的實用性和準確性。在準確評估可靠性后,合理地選擇維修策略制定優(yōu)化的維修決策是飛機維修保障的關(guān)鍵。目前,盡管功能檢查是飛機維修中最常用的維修策略,功能檢查的實際應(yīng)用遇到兩大問題:在某些條件下檢查的準確度不夠高;缺少潛在缺陷和延遲時間的實際樣本。目前的功能檢查模型多數(shù)沒有考慮維修項目實際退化過程對維修策略的限制,許多理論上很好的檢查策略在實際中卻不很準確,不能準確發(fā)現(xiàn)故障。根據(jù)退化過程對檢查間隔的約束,針對時間延遲模型的功能檢查,建立有約束的不等間隔檢查的費用率優(yōu)化模型,并且提出了衡量檢查準確性的指標。本文假設(shè)故障率在潛在缺陷發(fā)生前后是明顯不同的,然后提出一個分段分布和基于KS檢驗的時間序列層次聚類方法來估計潛在缺陷的發(fā)生時間。然后,能從壽命樣本中提取出延遲時間樣本,進一步估計出延遲時間分布。最后,因為壽命是延遲時間和潛在缺陷時間的總和,這樣在壽命分布被估計出后潛在缺陷時間可以輕松估計出。最后把本文的維修決策模型應(yīng)用到民用飛機的減速控制系統(tǒng)中取得了良好的效果。實例和仿真結(jié)果都顯示:不等間隔的檢查策略要比等間隔的檢查策略更加經(jīng)濟;和無約束的檢查模型相比,有約束的檢查模型雖然費用率數(shù)值可能不是最優(yōu),但是其確定的檢查策略更加高效準確并符合工程實際。另外,在民用飛機的維修領(lǐng)域,單目標模型有時是單調(diào)的,不存在最優(yōu)值,不能求出最優(yōu)維修策略。故本文綜合考慮多個目標,為維修策略建立多目標規(guī)劃模型,就可以求出同時接近多個目標的最優(yōu)策略。并且提出一個新的中心對稱的單純形優(yōu)化方法來求解該多目標優(yōu)化問題。實驗證明本文的維修模型能取得更高效更準確的決策。維修任務(wù)優(yōu)化組合不僅便于組織管理維修活動而且還能降低維修成本。但是在各種約束下實現(xiàn)維修任務(wù)的最優(yōu)組合,不僅涉及數(shù)值計算而且還是個NP難問題。本文討論了用遺傳算法和聚類模型兩個方法實現(xiàn)維修任務(wù)的組合優(yōu)化。首先,本文提出了一種適合求解組合優(yōu)化問題的遺傳算法--基于簇遍歷的遺傳算法,以定時更換策略的塊替換為例子,實現(xiàn)了維修任務(wù)的優(yōu)化組合。當只已知維修任務(wù)的間隔及其浮動范圍時,本文改進了模糊C均值聚類的模型以實現(xiàn)了維修任務(wù)的優(yōu)化組合。改進FCM模型中消除了代表聚類中心的變量,降低了維數(shù)。在試驗中,新的算法和模型都取得了良好效果。
[Abstract]:Maintenance is an important means to ensure the airworthiness of civil aircraft, the aircraft design, the whole process of manufacturing and operation, maintenance must be the focus of attention. For example, began compiling maintenance program in civil aircraft design and manufacture, maintenance manuals, application must be implemented in the aircraft maintenance, maintenance records reasonable information. The maintenance can not only reduce the cost of maintenance for the aircraft manufacturer to win the market but also for the airline cost savings, so maintenance is an important guarantee of aircraft work. This article mainly from the reliability assessment, maintenance strategy and maintenance task combination optimization three discussed in terms of civil aircraft maintenance. First, reliability is based on accurate assessment of civil aircraft maintenance the decision, no reliability information accurately is very difficult to make a correct judgement. Maintenance maintenance strategy is based on the reliability of maintenance projects, characteristics and Each project needs to determine the reasonable maintenance mode. Finally, in the actual execution of maintenance activities, often also for maintenance tasks to optimize the combination of the formation of the maintenance work package, which is not only the need of organization and management of maintenance activities, but also reduce the cost of maintenance. The censored small samples often produce civil aircraft in use process, which increases the reliability assessment of the difficulties. In view of real life censored samples have the same distribution and complete sample, if the truncated sample into a complete sample, may be in accordance with the proportion of the estimated frequency of complete sample frequency conversion censored samples. On the one hand based on the frequency of improvement on the standard life table method and product limit estimation, making them can accurately estimate various types of censored samples. On the other hand, the frequency as the weight factor, and variance of order statistics in the standard distribution, The formation of the weighted least squares method can accurately estimate various types of censored samples. MLE performance degradation due to the likelihood function with probability distribution function of censored data, based on the tectonic events and the truncated probability density function, the formation of the probability density function of censored data. Instead of the probability distribution function of traditional MLE with truncated probability density function the data, with the complete sample of the probability density function of the joint likelihood function. This function is composed of all likelihood probability density function, so the improved MLE conforms to the MLE definition. A large number of simulation experiments show that this improved method can well evaluate truncated small sample reliability estimation is more accurate than the traditional MLE. Especially when the censored data in a sample of a relatively high proportion of cases, the advantages of the improved method is more obvious. From the evaluation of elevator actuator For instance and aileron actuator reliability can be seen, compared with the traditional method, the improved method to assess the reliability of tendency of conservative and more accurate. Usually in terms of civil aircraft reliability, are assumed in the whole life cycle of risk have the same rules and fault obey the same distribution, so the use of reliability model unity in the whole life cycle. In fact, many civil aircraft equipment failure risk are complex, often with the running time has different characteristics and has multiple peaks, such as bathtub curve, therefore tend to have larger errors in the single model fitting equipment reliability method in the whole life cycle. If the the whole life cycle is divided into different sections according to the characteristics of risk changes, then fitting can more accurately approximate the reliability change. So this article takes the risk as a piecewise function, Two kinds of reliability distribution segment is proposed: a class of risk function is continuous; another kind of risk function can be discontinuous. In order to estimate the parameters of sectional reliability model, based on clustering of life samples, this paper discusses the reliability distribution of piecewise regression estimation and maximum likelihood estimation. Finally, because usually the information criterion is not suitable for piecewise distribution model, this paper improves the information criterion to evaluate the reliability of the segment of the models. After a great number of experiments and simulations verify the reliability of the segmentation model and its estimation method is more accurate than the traditional single model, especially with stage and multiple peaks in the risk. Sectional risk model in evaluating engine bleed air system and the front flap proximity sensor reliability in good performance, the sectional reliability model has practicability and good accuracy in accurate assessment. Estimation of reliability after reasonable selection of maintenance strategies, optimizing the maintenance decision-making is a key factor for aircraft maintenance safeguard. At present, although the function test is the most commonly used maintenance strategy for aircraft maintenance, application function tests encountered two major problems: under certain conditions the inspection accuracy is not high enough; the lack of potential defects and the actual sample the time delay function. Most current models do not consider maintenance inspection project degradation process of maintenance strategy, many good theoretical checking strategy in practice is not very accurate, can not accurately find fault. According to the constraint of the degradation process inspection interval, the time delay function test model, the establishment of a constraint the inspection fee rate of unequal interval optimization model, and put forward the measure of the accuracy of examination indicators. This assumption in the failure rate before and after the occurrence of potential defects is obvious The same, then proposed a piecewise distribution and time series clustering method based on KS test to estimate the time of occurrence of potential defects. Then, from the life of samples extracted samples to estimate the delay time, further delay time distribution. Finally, because life is the sum of the delay time and the potential defects in time, so can the potential defects of life distribution is estimated from the time after the estimated. Finally the application of easy maintenance decision model of this paper to speed control system for civil aircraft has achieved good results. Examples and simulation results showed that the unequal interval checking strategy to be more economic than the check interval strategy; compared with the check model without constraints the constraint checking model, while the rate of cost value may not be optimal, but the determination of inspection strategy is more efficient and accurate and practical. In addition, in the civil Aircraft maintenance field, single objective model is sometimes monotonous, there is no optimal value, can not find the optimal maintenance strategy. Therefore, considering the multiple targets, a multi-objective programming model for maintenance strategy, we can calculate the optimal strategy at the same time close to multiple targets. And put forward the method to solve the multi-objective optimization the problem of simplex optimization a new center of symmetry. Experiments show that this model can make maintenance more efficient and more accurate decisions. The maintenance task optimization not only for the organization and management of maintenance activities but also reduce the maintenance cost. But to achieve the optimum combination of maintenance tasks in a variety of constraints, not only relates to numerical calculation and a NP hard problem. This paper discusses combinatorial optimization using genetic algorithm and clustering model two methods to realize maintenance tasks. Firstly, this paper proposes a suitable for solving combinatorial optimization question The genetic algorithm -- genetic algorithm based on cluster traversal, to replace the timing block replacement policy for example, realize the optimization of combined maintenance tasks. When the only known maintenance task interval and the floating range, the improved fuzzy C means clustering model to achieve the optimal combination of maintenance tasks. The improved FCM model eliminate the clustering center representative variables, reduces the dimension. In the experiment, the new algorithm and the model have achieved good results.

【學位授予單位】：南京航空航天大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：V267
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本文編號：1430987