本文關(guān)鍵詞： 彎曲疲勞強度 疲勞裂紋擴展 斷面分析 分形維數(shù)　出處：《河南工業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：本課題所研究的大模數(shù)齒輪齒條為三峽大壩升船機所用的大模數(shù)產(chǎn)品,缺少相關(guān)可參考的標(biāo)準(zhǔn)和資料,為突破大模數(shù)齒輪齒條設(shè)計相關(guān)標(biāo)準(zhǔn)及文獻資料的局限性,本文主要針對三峽升船機模數(shù)為62.7mm的大模數(shù)齒條材料35CrNiMo的彎曲疲勞強度和裂紋擴展等進行了相關(guān)研究,主要包括以下方面。首先本文進行齒輪彎曲疲勞強度試驗研究。采用單齒加載法和成組法試驗方案進行試驗,對所得的數(shù)據(jù)進行擬合處理。最終得到齒輪的彎曲疲勞的極限應(yīng)力值,以及各個應(yīng)力與循環(huán)壽命的關(guān)系即P-S-N曲線。其次本文在齒輪彎曲疲勞極限理論的基礎(chǔ)上利用斷裂力學(xué)的理論,著重研究當(dāng)齒輪出現(xiàn)微小裂紋后其剩余壽命。利用有限元軟件和Franc3D進行仿真分析,獲得強度應(yīng)力因子等相關(guān)參數(shù),根據(jù)仿真所獲得的參數(shù)預(yù)測下一步裂紋的擴展情況,并生成下一步擴展的裂紋,循環(huán)迭代直至完全斷裂。再次本文對彎曲疲勞強度試驗中所產(chǎn)生的彎曲疲勞斷齒先做宏觀斷口分析,然后再對樣本做掃描電鏡分析,著重研究其裂紋源,以求找到導(dǎo)致該型號齒輪的斷裂原因,為預(yù)防該裂紋的產(chǎn)生提供依據(jù)。最后本文基于分形理論對裂紋擴展的路徑進行維數(shù)計算,尋找裂紋擴展路徑與維數(shù)之間的關(guān)系。首先利用相機采集整個裂紋擴展的圖像,然后利用Matlab軟件對所采集到的圖像進行處理,把RGB格式的圖像處理為二值圖。用計盒維數(shù)法對二值圖進行維數(shù)計算,最終得到相應(yīng)的裂紋分形維數(shù)。
[Abstract]:The large modulus gear rack studied in this paper is the large modulus product used in the three Gorges Dam ship lift, and lacks the relevant standards and data. In order to break through the limitation of design standards and literature of large modulus gear rack. In this paper, the bending fatigue strength and crack propagation of 35CrNiMo, a large modulus rack material with a modulus of 62.7 mm for the three Gorges ship lift, are studied. The main contents are as follows. Firstly, the bending fatigue strength of gears is studied in this paper. The single-tooth loading method and group method are used to test the fatigue strength. Finally, the ultimate stress value of gear bending fatigue is obtained by fitting the obtained data. The relationship between each stress and cyclic life is P-S-N curve. Secondly, the theory of fracture mechanics is used on the basis of the bending fatigue limit theory of gear. The residual life of gear with tiny crack is studied emphatically. Using finite element software and Franc3D to simulate and analyze, the relevant parameters such as intensity stress factor are obtained. According to the parameters obtained by simulation, the next crack propagation is predicted, and the crack of the next step propagation is generated. Cycle iteration until complete fracture. Again, the bending fatigue fracture of teeth produced in the bending fatigue strength test is analyzed first, then the sample is analyzed by scanning electron microscope, and the crack source is studied emphatically. In order to find out the cause of the fracture of the gear, and to provide a basis for the prevention of the crack. Finally, based on the fractal theory, the path dimension of the crack propagation is calculated. In order to find the relationship between the crack propagation path and the dimension, the image of the whole crack propagation is collected by the camera, and then the image is processed by the Matlab software. The image of RGB format is processed as a binary graph, and the dimension of the binary graph is calculated by box-counting dimension method, and the corresponding fractal dimension of crack is obtained.
【學(xué)位授予單位】：河南工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U642

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本文編號：1459974