切削参数对加工质量影响的有限元模拟

通过DEFORM软件模拟,研究了零件机械加工过程中切削速度、切削深度和进给量对切削力的影响,切削用量、切削深度和走力量对零件表面质量的影响。     

A new approach for modelling vertical stress distribution at the soil/tyre interface to predict the compaction of cultivated soils by using the PLAXIS code

Soil compaction by agricultural machines can have adverse effects on crop production and the environment. Different models based on the Finite Element Method have been proposed to calculate soil compaction intensity as a function of vehicle and soil properties. One problem when modelling soil compaction due to traffic is the estimation of vertical stress distribution at the soil surface, as the vertical stress is inhomogeneous (non-uniform) and depends on soil and tyre properties. However, uniform stress distribution at the soil/tyre interface is used to predict the compaction of cultivated soils in most FEM compaction models. We propose a new approach to numerically model vertical stress distribution perpendicular to the driving direction at the soil/tyre interface, employing the FEM models of PLAXIS code. The approach consists of a beam (characterised by its geometric dimensions and flexural rigidity) introduced at the soil surface and loaded with a uniform stress with the aim to simulate the action of a wheel at the soil surface. Different shapes of stress distribution are then obtained numerically at the soil surface by varying the flexural rigidity of the beam and the mechanical parameters of the soil. PLAXIS simulations show that the soil type (soil texture) modifies the shape of the stress distribution at the edges of the contact interface: a parabolic form is obtained for sand, whereas a U-shaped is obtained for clay. The flexural rigidity of the beam changes the shape of distribution which varies from a homogenous (uniform) to an inhomogeneous distribution (parabolic or U-shaped distribution). These results agree with the measurements of stress distributions for different soils in the literature. We compared simulations of bulk density using PLAXIS to measurement data from compaction tests on a loamy soil. The results show that simulations are improved when using a U-shaped vertical stress distribution which replaces a homogenous one. Therefore, the use of a beam (cylinder) with various flexural rigidities at the soil surface can be used to generate the appropriate distribution of vertical stress for soil compaction modelling during traffic.     

曲轴强度的接触有限元分析与算法比较

运用ANSYS软件对某四缸汽油机曲轴强度进行了接触有限元计算分析,详细讨论了载荷与边界条件的处理及ANSYS接触分析方法,并将曲轴强度的接触有限元法与其他有限元计算方法进行了比较分析。     

高压往复泵曲轴强度的有限元分析

为了提升高压往复泵的设计开发水平,以三缸单作用高压往复泵为研究对象,通过对各机构的运动分析和部件的受力计算,得到了曲轴的载荷变化规律。在Pro/E中建立了曲轴的三维实体模型,采用有限元方法对三种危险工况下的曲轴强度分别进行了应力分析,获得了最大主应力、最小主应力和Mises应力在曲轴上的分布规律,详细分析了各应力产生的原因及对曲轴强度的影响,有限元分析计算的结果为高压往复泵曲轴的设计研发提供了理论依据和技术支持。     

Ultimate Bearing Capacity Analysis of High Strength Single Angle Compression Member Eccentrically at One End

To analyze mechanical behavior of Q460 high strength single angle steel struts with an eccentric load at one end in transmission towers, experimental analysis and theoretical calculation were carried out to study the overall stability and local buckling of members. Spherical hinge bearing and double knife edge bearing were applied at axial end of specimens. Influence of some factors on bearing capacity of compression members with eccentricities at both ends was analyzed, such as the end supporting conditions and residual stresses. It was shown that whether spherical hinge bearing or double knife edge bearing was used at axial end, the mechanical behavior can be accurately presented and the residual stresses affected the ultimate load carrying capacity by about 5％ or less. Compared with different methods, such as experiment method、finite element method, method in the Guide for American Design of Latticed Steel Transmission Structure（ASCE101997）and method in Chinese Technical Regulation of Design for Tower and Pole Structure of Overhead Transmission Line (DL/T51542002), it was found that the calculated strength of high strength steel member by standard calculation method in DL/T51542000 was over conservative. According to the research results, the revised formulas of ASCE were proposed with dividing actual material strength by the resistance coefficient of rR=1.111. Therefore, the experimental results can provide reference for designing high strength Q460 single angle steel members compressed eccentrically at one end.     

Numerical analysis of noise radiation from motorcycle engine shell

FEM/BEM (Finite Element Method/Boundary Element Method) mode analysis of the noise radiation from motorcycle engine shell is conducted. The natural frequency is compared between FEM/BEM analysis and experimental analysis. The FEM/BEM results are agreed with the experiment results, which proves that the finite element model is correct. The frequency response is analyzed and the structure’s noise radiation is simulated by means of FEM/BEM, in order to predict the noise radiation from the motorcycle engine shell and gain the sound field characteristic outside the structure. The calculation data is compared with the experiment data in different frequency bands. The result shows high accordance, which indicates that this method is effective.     

用响应面有限元法分析既有混凝土桥梁的可靠性

基于响应面有限元的可靠度计算是采用有限元数值模拟来解决功能函数不能明确表示的结构可靠度计算问题的一类方法,对于大型复杂结构的可靠度分析有重要的意义.基于ANSYS的响应面法分析了一座既有桥梁的可靠性.数值模拟与试验结果对比表明,该方法可以很好地评价既有混凝土桥梁的可靠性,为结构可靠度分析计算提供了新的有效途径.     

纳米TiN改性的TiC基金属陶瓷刀具有限元分析

采用数值模拟技术并借助于大型有限元计算软件，通过二维金属切削过程的数值模拟，对纳米TiN改性的TiC基金属陶瓷刀具的应力分布进行了有限元仿真计算，并对该种材料刀具的几何参数进行了优化，得出较为合理的刀头几何参数。     

紫坪铺水利枢纽引水系统取消厂前伸缩节研究

结合紫坪铺水利枢纽工程的实际情况，采用三维有限元方法对该工程发电引水系统取消伸缩节的可行性进行了研究。计算结果表明，主厂房上游永久分缝处以一段垫层管代替常规伸缩节，结构位移和应力完全可以满足使用要求，从而达到了取消伸缩节、节省工程投资的目的。     

车用磁流变减振器的磁路设计

磁流变减振器磁路的设计是减振器设计中较为重要的一步,为使磁路的设计思路更加完善,对影响磁路性能的各关键问题应进行比较细致的分析。选择合理的磁路参数和设计方法决定着减振器的设计能否满足性能要求,利用有限元分析软件ANSYS对设计的磁路结构进行了仿真,结果表明设计的磁路结构满足性能要求,磁路设计方法较为合理,通过分析仿真结果可对磁路结构进一步优化,使设计的磁路结构性能得到最大的发挥。