多点冲击下TBM刀盘裂纹萌生—扩展全寿命预测

发布时间：2018-04-05 10:05

本文选题：TBM刀盘　切入点：疲劳寿命预测　出处：《大连理工大学》2015年硕士论文

【摘要】：随着经济社会转型,城镇化发展进入关键时期,地下空间的开发利用对于缓解地表空间紧张、完善基础设施建设具有深远影响,我国已成为硬岩隧道掘进设备(TBM)需求最大的国家。刀盘系统是影响TBM破岩效率的核心部件,但现有刀盘的设计较少考虑疲劳寿命,强振动环境下刀盘裂纹的萌生与扩展将极大影响施工效率甚至带来安全隐患。因此开展刀盘疲劳全寿命预测研究对于TBM安全服役具有重要意义。在深入理解疲劳裂纹萌生和扩展寿命预测理论与方法的前提下,本文针对TBM刀盘的疲劳全寿命预测问题,通过理论计算、仿真分析和试验研究的方式开展了相关研究,具体工作如下：(1)在分析刀盘受力特点的基础上,综合考虑计算精度和效率提出了一种计算TBM刀盘动应力的改进准静态法,使用这种方法计算了刀盘危险点和待测点的动应力。搭建了无线测试系统并对实际掘进工作中的TBM刀盘应力进行了测试,测试数据与计算结果均值的差别仅为3.2%,变化范围的差距则有9.8%,考虑到现场测试的偶然性可以表明改进准静态法计算刀盘动应力的有效性。(2)根据雨流计数方法对应力时间历程进行统计计数得到了应力幅值和均值的直方图,根据数理统计理论拟合了幅值的分布函数编制了应力程序谱,结合材料的S-N曲线和损伤累积准则预测了刀盘裂纹萌生寿命。并探讨了Miner准则和Chaboche准则对萌生寿命的预测效果以及应力次序对萌生寿命的影响。研究表明,Chaboche准则比Miner准则更加保守,低-高分级谱作用下萌生寿命更长。(3)考虑到刀盘结构复杂难以计算应力强度因子幅,以及承受随机应力的特点,使用了短时间尺度裂纹扩展模型,开展了弱约束条件下稳态裂纹扩展试验获得模型中的裂纹张开角参数。为了验证模型的适用性从刀盘整体结构中抽取了典型子结构,按照一定缩尺比设计了疲劳试验样件和预制裂纹,开展了刀盘子结构疲劳试验研究。最终将此裂纹扩展模型运用于预测某工程实际刀盘的裂纹扩展寿命预测。
[Abstract]:With the economic and social transformation, the development of urbanization has entered a critical period. The development and utilization of underground space has a far-reaching impact on alleviating the tension of surface space and improving infrastructure construction.China has become the largest demand for hard rock tunneling equipment TBMs.The cutter head system is the core component that affects the TBM rock breaking efficiency. However, the fatigue life is less considered in the design of the existing cutter head. The crack initiation and propagation of the cutter head under the strong vibration environment will greatly affect the construction efficiency and even bring about the hidden danger of safety.Therefore, it is very important for TBM to carry out the research on predicting the fatigue life of the cutter head.On the premise of deeply understanding the theory and method of fatigue crack initiation and propagation life prediction, this paper studies the fatigue life prediction of TBM cutters through theoretical calculation, simulation analysis and experimental research.The concrete work is as follows: 1) on the basis of analyzing the stress characteristics of the cutter head, an improved quasi-static method for calculating the dynamic stress of the TBM cutter head is put forward considering the calculation accuracy and efficiency. The dynamic stress of the cutting head dangerous point and the point to be measured is calculated by using this method.A wireless testing system is set up and the stress of TBM cutter head in actual tunneling is tested.The difference between the test data and the average value of the calculated results is only 3.2, and the difference in the range of variation is 9.8. Considering the contingency of the field test, it can be shown that the effectiveness of the improved quasi-static method for calculating the dynamic stress of the cutter head is based on the rain flow counting method.The histogram of stress amplitude and mean is obtained by statistical counting of force time history.According to the mathematical statistics theory, the stress program spectrum of the distribution function of amplitude is compiled, and the crack initiation life of the cutter head is predicted by combining the S-N curve of the material and the damage accumulation criterion.The prediction effect of Miner criterion and Chaboche criterion on the initiation life and the effect of stress order on the initiation life are discussed.The results show that the Chaboche criterion is more conservative than the Miner criterion, and the initiation life is longer under the action of low to high classification spectrum.) considering the complexity of the cutter head structure, it is difficult to calculate the amplitude of the stress intensity factor and bear the random stress.Using a short time scale crack growth model, the crack opening angle parameters of the model are obtained by a steady state crack growth test under the condition of weak constraints.In order to verify the applicability of the model, the typical substructures were extracted from the overall structure of the cutter head. Fatigue test samples and precast cracks were designed according to a certain scale ratio, and the fatigue test study of the knife plate structure was carried out.Finally, the crack propagation model is applied to predict the crack growth life of a practical cutter head.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U455.3

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