振冲器与土壤的动力学耦合特性分析

发布时间：2018-04-24 02:16

本文选题：振冲器 + 土力学　；参考：《陕西科技大学》2015年硕士论文

【摘要】：近几年建筑行业发展较快,为了能够让建筑物具有稳定性,这就要求对地基的稳定性及抗震性有很高的要求。振冲器是一种压实土壤的器械,成为了现代建筑行业的主要施工机械,而有效的对土壤压实已成为目前国内外研究的重点。土壤具有十分复杂的非线性特点,而且是非连续体,因此对于振冲器与土壤耦合分析是很有必要的。课题对土壤的物理性能进行理论分析:研究土壤力学、土壤及其压实性能,对土壤的三相指标与压实的有关指标进行分析。最终确立选择土壤动力本构模型为Drucker-Prager模型,此模型是在考虑静水压力广义的Mises屈服准则基础上建立起来的。课题以功率为75KW的振冲器为研究对象,介绍振冲器的主要结构及工作原理,之后对振冲器进行力学分析,在振动压实数学模型及动力学方程的基础上,得到了振冲器加速度与土壤紧密程度的力学关系。通过分析振冲器压实土壤的过程,得到土壤的塑性变形比较大,因此把土壤变形忽略而简化振冲器动力学分析的做法与实际情况是不符的。为了深入研究振冲器运动机理,对振冲器工作情况及结构进行分析研究,提取主要结构参数。在合理简化振冲器的动力学模型基础上,将振冲器的工作过程分为三个阶段来研究,并建立相应的动力学模型,得到振冲器工作阶段的动力学方程,最后得出系统方程组的解析解表达式。现场观察了振冲器结构并获取各结构的具体尺寸,运用Soild Works对振冲器进行三维建模。对各结构进行面与面的装配,得到振冲器整体的三维模型。在工作中水通过喷射管后由振冲顶尖喷出。高压的水流会对振冲器顶尖产生影响,流体与振冲器顶尖产生了复杂的流固耦合。针对这种现象用ANSYS单向流固耦合(FSI)分析,得出了水流对振冲器顶尖应力的影响。分析结果对于振冲器顶尖的工作结构及维护有一定的指导意义。对振冲器三维模型进行简化处理。之后定义材料属性、网格划分、约束方式,得到有限元模型,使用ANSYS软件对其进行模态分析,得出振冲器前6阶固有频率及固有振形。从而知道振冲器在工作时共振发生在哪个部位上,在后续的工作中使得振冲器避开共振频率工作,这样能够让振冲器的寿命提高。最后利用软件ANSYS/LS-DYNA来分析振冲器与土壤的耦合模型,在LS-PREPOST后处理软件中进行可视化后处理,得到二者的等效应力分布、接触力等情况。
[Abstract]:In recent years, the construction industry has developed rapidly. In order to make buildings have stability, it is necessary to have high requirements for foundation stability and seismic resistance. Vibrator is a kind of equipment for compacting soil, which has become the main construction machinery in modern construction industry, and the effective compaction of soil has become the focus of research at home and abroad. Soil has very complex nonlinear characteristics and is discontinuous, so it is necessary for the coupled analysis of vibrator and soil. In this paper, the physical properties of soil are analyzed theoretically: soil mechanics, soil and compaction properties are studied, and the three-phase index and compaction index of soil are analyzed. Finally, the soil dynamic constitutive model is chosen as Drucker-Prager model, which is based on the generalized Mises yield criterion of hydrostatic pressure. The main structure and working principle of the vibrator are introduced, and then the mechanical analysis of the vibrator is carried out. Based on the mathematical model and dynamic equation of vibration compaction, the main structure and working principle of the vibrator are introduced. The mechanical relationship between vibrator acceleration and soil compactness is obtained. By analyzing the process of compacting soil with vibrator, it is found that the plastic deformation of soil is relatively large, so the method of simplifying the dynamic analysis of vibrator by neglecting soil deformation does not accord with the actual situation. In order to study the motion mechanism of vibrator, the working condition and structure of vibrator were analyzed and the main structural parameters were extracted. On the basis of reasonably simplifying the dynamic model of the vibrator, the working process of the vibrator is divided into three stages to study, and the corresponding dynamic model is established, and the dynamic equation of the vibrator working phase is obtained. Finally, the analytical solution of the system equations is obtained. The vibrator structure was observed and the specific dimensions of each structure were obtained, and Soild Works was used to model the vibrator. The three-dimensional model of the vibrator is obtained by assembling the surfaces of each structure. At work, water is ejected through the jet tube by the vibrating tip. The flow of high pressure affects the center of vibrator, and the fluid and the center of vibrator produce complex fluid-solid coupling. In view of this phenomenon, the influence of water flow on the tip stress of vibrator is obtained by using ANSYS unidirectional fluid-solid coupling analysis. The analysis results have certain guiding significance for the working structure and maintenance of the vibrator center. The three-dimensional model of vibrator is simplified. The finite element model is obtained by defining the material attribute, mesh division and constraint mode. The modal analysis of the finite element model is carried out by using ANSYS software, and the first 6 natural frequencies and natural vibration shapes of the vibrator are obtained. In order to know which part of the vibrator resonance occurs in the operation, in the subsequent work, the vibrator can avoid the resonant frequency operation, which can improve the life of the vibrator. Finally, the coupling model between vibrator and soil is analyzed by software ANSYS/LS-DYNA, and the equivalent stress distribution and contact force are obtained by visual post-processing in LS-PREPOST post-processing software.
【学位授予单位】：陕西科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU435

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