柴油机缸盖螺栓动态应力分析方法研究
发布时间：2018-11-11 16:01
【摘要】：螺栓连接件是机械设备中比较常见,也比较重要的连接机构。缸盖螺栓连接着气缸盖、机体,是发动机零件中要求最高的螺栓之一。安装时,要承受较大的预紧力；发动机运转过程中,要承受复杂的交变载荷,这些载荷的大小、方向随着曲轴转角的改变而改变,所以缸盖螺栓也是柴油机受力最复杂的零件之一。因此对高强度螺栓进行强度校核研究十分重要。本文以6L16/24型柴油机缸盖螺栓为例,对螺栓连接件的动态特性及建模方法进行研究。 本文以不同的计算方法来研究缸盖螺栓的动态特性：基于VID2230准则的静强度校核和疲劳强度校核,将两种方法取得的结果进行对比,然后总结比较全面的螺栓连接件的动态特性建模及分析方法,主要工作如下： ①利用HyperMesh软件,对柴油机的三维模型进行简化,忽略对缸盖螺栓受力影响不大的零部件,建立约束、赋予材料属性、单元类型之后,将.dbb文件导入到NSYS中,建立有限元模型。 ②在ADAMS软件中计算柴油机工作过程中主要受力部位一个工作循环的动态力,并作为柴油机动态分析中的主要载荷。 ③在ANSYS中对四根缸盖螺栓施加预紧力之后,在气缸盖、机体、气缸套上分别施加相对应的一个工作循环的动态载荷。 ④根据ANSYS计算结果得到的应力云图,分析缸盖螺栓在柴油机一个工作循环中的不同时刻缸盖螺栓的受力情况,并依据结果来进行螺栓的强度校核。 ⑤通过对缸盖螺栓做动态应力应变的测试实验,测得选取的某两个测点的动应变变化曲线,并与有限元计算结果中得到的动应变曲线对比。验证有限元计算的准确性。 ⑥按照VDI2230准则所述的方法,对处于第四缸达到最大爆发压力时刻的缸盖螺栓进行强度计算 通过两种方法的计算,有限元计算得到第四缸达到最大爆发压力时刻,螺栓承受的最大应力是679MPa,而按照VDI2230准则,计算同一时刻螺栓承受的最大应力是674MPa,两者的计算结果很接近,经计算,缸盖螺栓的安全系数能够满足使用要求,说明这两种方法的有效性,也证明了有限元计算和VDI2230准则计算在研究其他类型的螺栓连接件中的可行性。同时利用这两种方法计算得到了比较准确的结果,也为螺栓连接件的强度计算积累了比较可靠的计算方法,可以为各个使用单位研究螺栓连接件提供研究方法,进而提高效率,节省成本。
[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.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH131.3
本文编号：2325372
[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.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH131.3
【引证文献】
相关期刊论文 前1条
1 李玲;;管道阀门螺栓断裂的原因分析[J];机械工程材料;2013年05期
相关硕士学位论文 前1条
1 胡浩;螺纹联接件参数化CAD系统研究[D];西南交通大学;2013年
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