【摘要】：軸類零件是機(jī)械系統(tǒng)中的重要組成部分,應(yīng)用非常廣泛,此類零件一旦發(fā)生失效,輕則使機(jī)械運(yùn)轉(zhuǎn)停止無(wú)法正常工作、重則造成機(jī)毀人亡等無(wú)法挽回的損失。由于軸類零件的設(shè)計(jì)工作相當(dāng)繁瑣,在設(shè)計(jì)過(guò)程中一旦出現(xiàn)差錯(cuò)就可能造成軸系乃至整套設(shè)備的失效。本文以軸類零件的結(jié)構(gòu)工藝性設(shè)計(jì)缺陷和材料選擇設(shè)計(jì)缺陷為研究對(duì)象,采用不同的方法對(duì)其進(jìn)行了辨識(shí)。經(jīng)驗(yàn)不足的設(shè)計(jì)人員設(shè)計(jì)出的零件結(jié)構(gòu)很可能會(huì)存在加工費(fèi)用高、無(wú)法加工等缺陷,為此,本文提出了一種基于特征元推理策略的軸類零件結(jié)構(gòu)工藝性設(shè)計(jì)缺陷辨識(shí)方法。軸類零件的結(jié)構(gòu)特征承載著零件中的所有結(jié)構(gòu)設(shè)計(jì)信息,將軸類零件的設(shè)計(jì)信息存儲(chǔ)在零件信息樹中,建立了特征元知識(shí)庫(kù),提出了基于特征元的推理策略,并采用該推理策略對(duì)軸類零件的結(jié)構(gòu)工藝性設(shè)計(jì)缺陷進(jìn)行了辨識(shí)。過(guò)盈配合中過(guò)盈量的傳統(tǒng)計(jì)算方法忽略了配合邊緣的應(yīng)力集中問(wèn)題,過(guò)大的邊緣應(yīng)力會(huì)造成軸轂配合部分壓潰或微動(dòng)磨損等,為解決傳統(tǒng)計(jì)算方法的不足,提出了基于有限元方法與支持向量機(jī)模型的過(guò)盈量設(shè)計(jì)缺陷辨識(shí)方法。采用有限元方法分析出過(guò)盈配合接觸應(yīng)力的影響因素,并用支持向量機(jī)構(gòu)建出了過(guò)盈量及其影響因素之間的關(guān)系模型,利用該模型可以精確地計(jì)算出發(fā)生塑性變形時(shí)的最大過(guò)盈量,若原設(shè)計(jì)過(guò)盈量超過(guò)了計(jì)算出的最大過(guò)盈量,則可以確定原設(shè)計(jì)存在著過(guò)盈量設(shè)計(jì)缺陷。傳統(tǒng)的滾珠絲杠抗過(guò)載能力設(shè)計(jì),忽略了螺旋升角的影響。本文在綜合考慮到螺旋升角以及滾珠載荷分布不均的影響,對(duì)已有的滾珠絲杠接觸力學(xué)模型進(jìn)行了改進(jìn),推導(dǎo)了在臨界塑性變形下臨界軸向載荷的計(jì)算公式,據(jù)此公式可以判斷滾珠絲杠是否存在結(jié)構(gòu)參數(shù)設(shè)計(jì)缺陷。材料選擇是一個(gè)多目標(biāo)決策過(guò)程,考慮不周很容易造成選材不滿足設(shè)計(jì)要求,為此,提出了一種基于改進(jìn)物元模型的材料選擇設(shè)計(jì)缺陷辨識(shí)模型。對(duì)物元模型中隸屬度的計(jì)算方法進(jìn)行改進(jìn),引入數(shù)值型關(guān)聯(lián)度和區(qū)間型關(guān)聯(lián)度,克服了無(wú)法對(duì)區(qū)間物元進(jìn)行計(jì)算的不足之處。應(yīng)用改進(jìn)的物元模型計(jì)算出各備選材料的等級(jí)隸屬度和等級(jí)特征值,由這兩個(gè)參數(shù)就可判斷備選材料是否存在設(shè)計(jì)缺陷。
[Abstract]:Shaft parts are an important part of mechanical system, which are widely used. Once this kind of parts fail, the machinery can not work properly when it fails, and the irreparable losses such as machine destruction and human death will be caused by heavy ones. Because the design work of shaft parts is very tedious, once there is an error in the design process, it may cause the failure of shafting and even the whole equipment. In this paper, the structural process design defects and material selection design defects of shaft parts are taken as the research object, and the structural process design defects and material selection design defects of shaft parts are identified by different methods. The part structure designed by inexperienced designers is likely to have some defects, such as high machining cost and inability to machine. therefore, this paper proposes a defect identification method for structural process design of shaft parts based on feature element reasoning strategy. The structural features of shaft parts carry all the structural design information in the parts. The design information of shaft parts is stored in the part information tree, the feature element knowledge base is established, and the reasoning strategy based on feature elements is put forward. The structural process design defects of shaft parts are identified by using the reasoning strategy. The traditional calculation method of interference amount in interference fit ignores the problem of stress concentration at the edge of fit, and excessive edge stress will cause partial crushing or fretting wear of hub fit, etc., in order to solve the deficiency of traditional calculation method. A defect identification method for interference design based on finite element method and support vector machine model is proposed. The influencing factors of interference fit contact stress are analyzed by finite element method, and the relationship model between interference and its influencing factors is established by using support vector mechanism. The maximum interference in plastic deformation can be calculated accurately by using the model. If the interference of the original design exceeds the calculated maximum interference, it can be determined that there is a defect in the design of the original design. The traditional design of anti-overload ability of ball screw ignores the influence of spiral angle. In this paper, considering the influence of spiral angle and uneven distribution of ball load, the existing contact mechanical model of ball screw is improved, and the formula for calculating critical axial load under critical plastic deformation is derived. According to this formula, we can judge whether there are structural parameter design defects in ball screw. Material selection is a multi-objective decision-making process, which is easy to cause material selection not to meet the design requirements. Therefore, a defect identification model of material selection design based on improved matter-element model is proposed. The calculation method of membership degree in matter-element model is improved, and the numerical correlation degree and interval correlation degree are introduced to overcome the shortcomings that can not be used to calculate interval matter-element. The grade membership degree and grade eigenvalue of each alternative material can be calculated by using the improved matter-element model, and the design defects of the alternative material can be judged by these two parameters.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TH16;TH133.2

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本文編號(hào)：2477173