基于压力-位移曲线和最大压装力的衔铁组件压装质量预测

对衔铁组件过盈联接压装进行有限元分析,并得到压力-位移曲线和最大压装力,从而实现了衔铁组件过盈联接压装质量预测。根据衔铁组件各零件的实际尺寸建立零件实体模型,然后利用有限元软件ANSYS Workbench建立相应的有限元模型,最后对压装过程进行结构静力学仿真。为了验证仿真结果的正确性,利用已有的压装设备进行压装实验。实验结果表明,有限元分析得到的压力-位移曲线与实验结果基本一致。除此之外,最大压装力的有限元分析结果也和实现结果基本一致,最大偏差仅为4.6%,是可以接受的。上述比较说明了压力-位移曲线和最大压装力的仿真结果可以用于压装质量的预测。

压力-位移曲线在压装工艺中的应用研究

基于圆柱面过盈联接的计算公式,对双金属卷制衬套压装过程的压力变化规律进行了研究,提出了一种通过监控压力-位移曲线来实现压装防错的方法。

电子液压线控制动压力控制开发

为了克服电子液压线控制动系统(EHB)死区、摩擦及系统不确定性对压力控制的响应和精度的影响,文章提出一种新的闭环-前馈相结合的压力控制策略。该策略首先建立电子液压线控制动系统的动力学模型,并分析压力与活塞位移和速度相互关系,根据试验台架获取主缸压力与活塞位移的关系曲线;同时提出以压力-速度-电流为主的主控制回路,并以主缸活塞位置为辅助量的压力补偿控制策略;最后在斜坡和正弦工况下进行测试,结果表明该方法能够保证压力跟踪的快速响应和稳态跟踪性能。

新型位移—压力曲线轴承压装机的原理

概述新型位移—压力曲线滚动轴承压装机的原理、特点及实现轴承与轴颈相对位移准确测量的方法。利用此项技术改进的滚动轴承压装机客观反映装配过程中力与运动的关系，并进一步提高了车辆检修的自动化程度。

Displacement Trends of Slow-moving Landslides: Classification and Forecasting

A framework is proposed to characterize and forecast the displacement trends of slow-moving landslides, defined as the reactivation stage of phenomena in rocks or fine-grained soils, with movements localized along one or several existing shear surfaces. The framework is developed based on a thorough analysis of the scientific literature and with reference to significant reported case studies for which a consistent dataset of continuous displacement measurements is available. Three distinct trends of movement are defined to characterize the kinematic behavior of the active stages of slow-moving landslides in a velocity-time plot: a linear trend-type I, which is appropriate for stationary phenomena; a convex shaped trend-type II, which is associated with rapid increases in pore water pressure due to rainfall, followed by a slow decrease in the groundwater level with time; and a concave shaped trend-type III, which denotes a non-stationary process related to the presence of new boundary conditions such as those associated with the development of a newly formed local slip surface that connects with the main existing slip surface. Within the proposed framework, a model is developed to forecast future displacements for active stages of trend-type II based on displacement measurements at the beginning of the stage. The proposed model is validated by application to two case studies.

Axial compression physical testing of traditional and bird beak SHS T-joints

The static tests of nine traditional and bird beak square hollow structure(SHS) T-joints with different β values and connection types under axial compression at brace end were carried out. Experimental test schemes, failure modes of specimens, jack load-vertical displacement curves, jack load-deformation of chord and strain intensity distribution curves of joints were presented. The effects of β and connection types on axial compression property of joints were studied. The results show that the ultimate axial compression capacity of common bird beak SHS T-joints and diamond bird beak SHS T-joints is larger than that of traditional SHS T-joint specimens with big values of β. The ultimate axial compression capacity of diamond bird beak SHS T-joints is larger than that of common bird beak SHS T-joints. As β increases, the increase of the ultimate axial compression capacity of diamond bird beak SHS T-joints over that of common bird beak joints grows. The ultimate axial compression capacity and the initial axial stiffness of all kinds of joints increase as β increases, and the initial axial stiffness of the diamond bird beak SHS T-joints is the largest. The ductilities of common bird beak and diamond bird beak SHS T-joints increase as β increases, but the ductility of the traditional SHS T-joints decreases as β increases.

主被动状态间墙体侧向位移与土压力关系

为了研究从静止到主动状态或从静止到被动状态下墙体侧向位移与墙背土压力大小的关系,以应力Mohr圆为出发点,通过引入内摩擦发挥角,推导了主动与被动状态间土压力与内摩擦发挥角的统一表达式。根据所构建的墙体位移与土体剪应变几何方程以及等极限应变下的剪应变-剪应力理想非线弹塑性物理模型,建立了能基本反映土体应力-应变特性和墙后填土初始应力状态的墙体位移-土压力统一函数关系式,并结合Coulomb土压力模型近似考虑了墙背与填土间摩擦力的影响。研究结果表明:影响墙体位移-土压力关系的核心要素是墙背初始应力状态、墙后滑移区范围及填土应力-应变特性;初始侧压力系数的增加,直接导致进入主动与被动状态所需墙体位移出现相应的增大和减小,墙体位移-土压力曲线沿水平轴呈现出整体平移的变化;土体内摩擦角和墙土摩擦角的改变会引起滑移区范围的变化,从而使墙体位移-土压力曲线整体放大或缩小;填土应力-应变特性是墙体位移-土压力关系的微观本质,其模量比与极限剪应变对墙体位移-土压力曲线的平缓程度及极限状态下的墙体位移大小影响显著。

基于汽车启动机轴承的伺服压装机设计

为解决汽车启动机轴承压装精度和可控度不佳的问题,文章采用具有伺服控制功能的电动缸解决这一问题。伺服压装机针对不同型号的轴承压装的需求配备过渡板,在过渡板中加工导向定位,方便各种车型样品之间快速切换。设备的控制系统以西门子PLC和触摸屏为控制器,拉压力传感器、增量旋转光电编码器等为反馈单元,电动缸为执行机构,实现对压装过程中压力闭环、位置半闭环和速度的控制,具有实时监控工作过程、故障报警等功能。该套伺服压装设备运行结果表明,轴承压装精度高,完成质量优良,运行系统稳定可行,极大的降低了工件的损耗。

衔铁组件装配中的过盈联接分析与质量控制

为预测衔铁组件压装质量,以衔铁组件压装过程为研究对象,利用有限元软件Ansys Workbench对压装过程进行仿真分析,从而得到过盈量和压力-位移曲线的合理范围。在此基础上,对衔铁倾斜压装进行仿真研究,结果表明对压装平行度有影响的是压装面和零件内孔的倾斜角度,当施压圆台的压装面或零件内孔倾斜0.03°时,零件将造成损坏,因此在加工施压圆台压装面和精密零件内孔时,要满足倾斜角度<0.03°。在上述仿真研究的基础上,研制了基于压力传感器、光栅尺、机器视觉的精密压装实验设备,并在所研制的压装设备上进行压装实验,结果表明,仿真分析所得的压力-位移曲线和压装实验所得结果之间的差别很小,而且仿真分析得到的最大压装力与压装实验结果最大偏差只有2.3%。此外,通过拆卸实验得到的最大压出力能够满足使用要求,并且比最大压装力低15%。根据上述比较结果可以确定,压装实验结果是正确的,进而证明了仿真结果可以用来预测压装质量。