【摘要】：螺栓連接件是機械設備中比較常見,也比較重要的連接機構(gòu)。缸蓋螺栓連接著氣缸蓋、機體,是發(fā)動機零件中要求最高的螺栓之一。安裝時,要承受較大的預緊力；發(fā)動機運轉(zhuǎn)過程中,要承受復雜的交變載荷,這些載荷的大小、方向隨著曲軸轉(zhuǎn)角的改變而改變,所以缸蓋螺栓也是柴油機受力最復雜的零件之一。因此對高強度螺栓進行強度校核研究十分重要。本文以6L16/24型柴油機缸蓋螺栓為例,對螺栓連接件的動態(tài)特性及建模方法進行研究。 本文以不同的計算方法來研究缸蓋螺栓的動態(tài)特性：基于VID2230準則的靜強度校核和疲勞強度校核,將兩種方法取得的結(jié)果進行對比,然后總結(jié)比較全面的螺栓連接件的動態(tài)特性建模及分析方法,主要工作如下： ①利用HyperMesh軟件,對柴油機的三維模型進行簡化,忽略對缸蓋螺栓受力影響不大的零部件,建立約束、賦予材料屬性、單元類型之后,將.dbb文件導入到NSYS中,建立有限元模型。 ②在ADAMS軟件中計算柴油機工作過程中主要受力部位一個工作循環(huán)的動態(tài)力,并作為柴油機動態(tài)分析中的主要載荷。 ③在ANSYS中對四根缸蓋螺栓施加預緊力之后,在氣缸蓋、機體、氣缸套上分別施加相對應的一個工作循環(huán)的動態(tài)載荷。 ④根據(jù)ANSYS計算結(jié)果得到的應力云圖,分析缸蓋螺栓在柴油機一個工作循環(huán)中的不同時刻缸蓋螺栓的受力情況,并依據(jù)結(jié)果來進行螺栓的強度校核。 ⑤通過對缸蓋螺栓做動態(tài)應力應變的測試實驗,測得選取的某兩個測點的動應變變化曲線,并與有限元計算結(jié)果中得到的動應變曲線對比。驗證有限元計算的準確性。 ⑥按照VDI2230準則所述的方法,對處于第四缸達到最大爆發(fā)壓力時刻的缸蓋螺栓進行強度計算 通過兩種方法的計算,有限元計算得到第四缸達到最大爆發(fā)壓力時刻,螺栓承受的最大應力是679MPa,而按照VDI2230準則,計算同一時刻螺栓承受的最大應力是674MPa,兩者的計算結(jié)果很接近,經(jīng)計算,缸蓋螺栓的安全系數(shù)能夠滿足使用要求,說明這兩種方法的有效性,也證明了有限元計算和VDI2230準則計算在研究其他類型的螺栓連接件中的可行性。同時利用這兩種方法計算得到了比較準確的結(jié)果,也為螺栓連接件的強度計算積累了比較可靠的計算方法,可以為各個使用單位研究螺栓連接件提供研究方法,進而提高效率,節(jié)省成本。
[Abstract]:Bolt connection is a common and important connection mechanism in mechanical equipment. The cylinder head bolt is connected with the cylinder head and block, which is one of the most demanding bolts in engine parts. Installation, to bear a larger pre-tightening force; In the process of engine operation, complex alternating loads are required, and the magnitude and direction of these loads change with the change of crankshaft angle, so cylinder head bolts are also one of the most complicated parts of diesel engine. Therefore, it is very important to study the strength of high strength bolts. Taking the cylinder head bolts of 6L16/24 diesel engine as an example, the dynamic characteristics and modeling method of bolt connections are studied in this paper. In this paper, the dynamic characteristics of cylinder head bolts are studied with different calculation methods: static strength check and fatigue strength check based on VID2230 criterion, and the results obtained by the two methods are compared. The main work is as follows: 1 using HyperMesh software to simplify the three-dimensional model of diesel engine, ignoring the parts which have little effect on the cylinder head bolt force. After the constraint is established, the material attribute is given, and the element type is given, the. Dbb file is imported into the NSYS and the finite element model is established. (2) calculate the dynamic force of a working cycle in the main force position of the diesel engine in the ADAMS software, and take it as the main load in the dynamic analysis of the diesel engine. (3) after applying pretightening force to four cylinder head bolts in ANSYS, dynamic loads corresponding to one working cycle are applied on cylinder head, block and cylinder liner respectively. According to the stress cloud diagram obtained by ANSYS, the stress of cylinder head bolt at different times in a working cycle of diesel engine is analyzed, and the strength of the bolt is checked according to the result. (5) the dynamic strain curves of two selected measuring points are measured by testing the dynamic stress-strain curves of cylinder head bolts, and compared with the dynamic strain curves obtained by finite element method. Verify the accuracy of finite element calculation. 6According to the method described in VDI2230 criterion, the strength of cylinder head bolts at the time when the fourth cylinder reaches the maximum burst pressure is calculated. Through the calculation of two methods, the finite element method is used to calculate the fourth cylinder to reach the maximum burst pressure moment. The maximum stress of bolt is 679 MPA, and according to VDI2230 criterion, the maximum stress of bolt at the same time is 674 MPA. The calculated results are very close. By calculation, the safety factor of cylinder head bolt can meet the requirement of application. The validity of the two methods is illustrated, and the feasibility of finite element calculation and VDI2230 criterion calculation in studying other types of bolted connectors is also proved. At the same time, more accurate results are obtained by using these two methods, and a more reliable calculation method is accumulated for the strength calculation of bolt connectors, which can provide a research method for the study of bolt connectors by various user units, and then improve the efficiency. Save costs.
【學位授予單位】：武漢理工大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TH131.3

【引證文獻】

相關(guān)期刊論文 前1條

1 李玲;;管道閥門螺栓斷裂的原因分析[J];機械工程材料;2013年05期

相關(guān)碩士學位論文 前1條

1 胡浩;螺紋聯(lián)接件參數(shù)化CAD系統(tǒng)研究[D];西南交通大學;2013年

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本文編號：2325372