本文選題：p-S-N曲線 + 成組法��； 參考：《東北大學(xué)》2011年碩士論文

【摘要】：考慮到疲勞試驗(yàn)數(shù)據(jù)的分散性,將疲勞壽命與一定的可靠度聯(lián)系起來,從而可以得到一組不同可靠度p下的S-N曲線,即可靠度-應(yīng)力-疲勞壽命曲線,稱之為p-S-N曲線。p-S-N曲線廣泛應(yīng)用于表征材料和零件疲勞性能,故又稱為概率疲勞性能曲線。對于承受交變載荷的材料而言,該曲線是一種十分重要的基礎(chǔ)設(shè)計(jì)資料,它代表了更客觀、更完整的應(yīng)力-壽命關(guān)系。 成組法是當(dāng)前通用的p-S-N曲線標(biāo)準(zhǔn)測試方法,該方法充分考慮到了試樣疲勞強(qiáng)度數(shù)據(jù)的隨機(jī)性和分散性,在試驗(yàn)中使用較多的試樣。成組法試驗(yàn)結(jié)果能滿足一定的統(tǒng)計(jì)要求,較真實(shí)地反映母體的特征,試驗(yàn)精度與置信度均較高。但是,由于成組法需要的試樣較多,從而直接導(dǎo)致試驗(yàn)所需時間長,工作量大,費(fèi)用高。針對傳統(tǒng)成組法的缺點(diǎn),國內(nèi)外學(xué)者運(yùn)用經(jīng)典的疲勞理論和數(shù)理統(tǒng)計(jì)工具,提出了一些高效或簡化的試驗(yàn)方法,以減少試驗(yàn)工作量。這類方法中,有的是建立在單點(diǎn)法得出的中值S-N曲線基礎(chǔ)之上,有的試驗(yàn)的樣品數(shù)量太少,使所得結(jié)果的準(zhǔn)確性和置信度下降,難以滿足工程的要求。 本文運(yùn)用性能-壽命概率映射原理,認(rèn)為材料性能處于其母體分布某一概率分位點(diǎn)的試樣,在任何應(yīng)力水平下的壽命都將處于對應(yīng)于該水平的壽命母體分布的同一概率分位點(diǎn)上。因而,不同應(yīng)力水平下的壽命分布存在映射關(guān)系,不同應(yīng)力水平下的各壽命樣本點(diǎn)之間存在一一對應(yīng)關(guān)系。根據(jù)這個對應(yīng)關(guān)系,就可以把不同應(yīng)力水平下的壽命試驗(yàn)數(shù)據(jù)轉(zhuǎn)換到某一個指定的應(yīng)力水平上,形成樣本聚集和信息融合效應(yīng),進(jìn)而進(jìn)行壽命分布參數(shù)估計(jì)。 本文設(shè)計(jì)了基于性能-壽命概率映射原理的小樣本p-S-N曲線試驗(yàn)方案,即新型小子樣法。該方法基于疲勞壽命服從對數(shù)正態(tài)分布,且對數(shù)壽命均值和標(biāo)準(zhǔn)差均與應(yīng)力水平呈線性關(guān)系的假設(shè),以及方差統(tǒng)計(jì)檢驗(yàn)原理,最終能夠用較少的試樣試驗(yàn)得出置信度較高的p-S-N曲線。
[Abstract]:Considering the dispersion of fatigue test data, a set of S-N curves under different reliability p can be obtained by associating fatigue life with certain reliability, that is, the reliability-stress-fatigue life curve. It is called p-S-N curve. P-S-N curve is widely used to characterize the fatigue properties of materials and parts, so it is also called probabilistic fatigue performance curve. For materials subjected to alternating load, the curve is a very important basic design data, which represents a more objective and complete stress-life relationship. Group method is a common standard test method for p-S-N curves. This method takes full account of the randomness and dispersion of fatigue strength data of samples and is used more frequently in the test. The results of the group test can meet certain statistical requirements and reflect the characteristics of the parent body more truthfully. The precision and confidence of the test are both high. However, due to the large number of samples needed by the group method, the test time is long, the workload is large and the cost is high. Aiming at the shortcomings of the traditional group method, the domestic and foreign scholars put forward some efficient or simplified test methods by using the classical fatigue theory and mathematical statistics tools, in order to reduce the test workload. Some of these methods are based on the median S-N curve obtained by the single point method, and some of the samples are too small to reduce the accuracy and confidence of the obtained results, which is difficult to meet the requirements of engineering. Based on the principle of performance-life probabilistic mapping, it is considered in this paper that the material's properties are at a probability locus of its parent body. The lifetime at any stress level will be at the same probability locus corresponding to the lifetime parent distribution at that level. Therefore, there is a mapping relationship between the life distribution at different stress levels and a one-to-one correspondence between the life sample points at different stress levels. According to the corresponding relation, the life test data under different stress levels can be converted to a certain stress level, and the effect of sample aggregation and information fusion can be formed, and then the life distribution parameters can be estimated. In this paper, a small sample p-S-N curve test scheme based on the principle of performance-life probability mapping is designed, that is, a new small sample method. This method is based on the assumption that the fatigue life suit is distributed from logarithmic normal, and the logarithmic life mean and standard deviation are linearly related to the stress level, as well as the principle of variance statistical test. Finally, the p-S-N curve with higher confidence can be obtained with less sample test.
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2011
【分類號】：TH140.7

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