石英挠性加速度计表头稳定性实验研究

高精度石英挠性加速度计对表头稳定性提出了较高的要求,而垂直敏感轴方向加速度对表头稳定性的影响容易被忽视。首先对表头中摆片组件在垂直敏感轴方向加速度作用下的动力学规律进行了研究;然后设计了基于开环阶跃实验的表头稳定性测试方法;搭建实验平台,在重力场中对摆片组件与重力加速度夹角为0°和180°的情况进行了实验。实验结果表明:摆片组件与重力加速度夹角为0°时,摆片摆动幅度小,石英挠性加速度计表头稳定性好。     

结合ANSYS Workbench的挠性梁强度分析

石英摆片是石英挠性加速度计的关键部件,挠性梁是摆片最重要的部分,它的强度计算一直是极为重要的课题。若挠性梁力学强度不足,在受到一定程度的力学冲击后,会出现断裂失效。从石英挠性加速度计的工作原理以及挠性梁的结构展开,分别从输入轴方向、摆轴方向和输出轴方向对挠性梁的力学强度进行了计算。由于理论计算的局限性,应用ANSYS Workbench软件进行了仿真,最终得出了一个可靠的计算方法。在后续的石英挠性梁设计过程中,可依据此计算方案进行初步的评估分析,以免加工成型后的挠性梁不能满足使用要求。     

超高分辨率石英挠性加速度计设计研究

目前国内通用的石英挠性加速度计分辨率一般为1×10-6 g,无法满足重力测量和重力梯度测量等微小加速度信号测量领域的使用要求。在分析高精度重力梯度仪对加速度计分辨率使用要求的基础上,进行超高分辨率石英挠性加速度计设计研究,提出超高分辨率石英挠性加速度计的设计方案并完成了仿真分析及实物装配,实物分辨率达到了1×10-9 g,相较传统石英挠性加速度计提升了2～3个数量级,为后续更高分辨率的加速度计设计研究提供了依据。     

基于平面线圈的石英挠性加速度计的初步设计

针对石英挠性加速度计目前存在的稳定性不好、温漂较大及不能兼顾大量程和高灵敏度测量等问题,提出了使用通电线圈代替永磁材料提供支承磁场,在石英摆片上双面光刻螺旋线圈作为力矩线圈的构想,并以此为基础初步设计了基于平面线圈、灵敏度可调的石英挠性加速度计.经过建模分析,可以达到预想的效果.     

挠性摆式加速计摆组件应力和变形计算分析

对摆组件在各种状态下的应力和变形进行计算,提出了对挠性关节受力状态较有利的放置方案,对装配误差对仪表精度的影响作了探讨,本文对精密仪器仪表的设计制作和存贮有参考价值.     

挠性摆式微硅加速度计的有限元分析

】微硅加速度计是近年来发展起来的新型器件,在结构设计阶段必须对其进行力学分析,以期对使用条件下的摆片位移、应力等作到心中有数。本文采用有限元分析方法对挠性摆式微硅加速度计进行有限元分析,其中包括对未封装及封装后实体单元进行敏感轴位移、侧向位移、横向灵敏度、受力情况等分析。分析结果表明所设计的微硅加速度计符合仪表性能要求。     

石英挠性加速度计测量误差的机电动力学分析

石英挠性加速度计测量误差的机电动力学分析＊贾建援仇原鹰甄明文贵印（西安电子科技大学电子机械学校西安７１００７１）（中国工程物理研究院５所）０引言目前，国内外批量生产的石英挠性加速度计的测量精度已达到或超过１μｇ，但由于产品在制造或装配中的误差，使得成...     

悬丝摆式加速度计底座组件自动装配与焊接控制

悬丝摆式加速度计具有小型化、大量程和抗冲击的特点，在航空航天领域得到广泛的应用。其底座与摆组件的精密装配，目前仍以人工装配为主，具有装配精度差、悬丝张紧力不易控制，人工焊接时焊接参数难以保证、焊点质量不佳等问题，导致产品的良品率较低。为此，研发了一套悬丝摆式加速度计底座组件自动装配与焊接设备。根据零件特点与装配环境，采用视觉与力觉反馈控制，实现底座与摆组件位姿和悬丝张紧力的自动调整。基于C++语言，开发了分层架构的控制软件。设计温度反馈控制的焊接工艺流程与焊接策略，并通过有限元仿真与焊接实验进行验证。实验结果表明：该设备可实现自动装配与焊接功能，底座组件的装配精度与焊接质量符合技术指标要求，提高了产品质量。     

基于区域灰度梯度差异的摆片基片特征 尺寸视觉测量方法

石英摆片是石英挠性加速度计的核心器件,其关键特征尺寸的加工精度由摆片基片加工精度决定。常规使用工具显微镜对基片表面特征尺寸进行测量,此测量过程复杂、重复性精度弱且效率低。提出了基于区域灰度梯度差异的摆片基片特征尺寸测量方法。首先对视觉测量系统硬件结构进行了设计研制,然后建立了基于区域灰度梯度的摆片基片边缘检测算法,其次围绕摆片基片结构特点提出了其特征边缘点的搜索分类方法,最后开展了摆片基片特征尺寸测量实验。实验结果表明,提出边缘检测方法在摆片基片圆心拟合偏差小于3μm的情况下可替代Zernike矩方法以提高边缘检测效率;所研测量系统2 s内即可完成摆片基片特征尺寸测量且不同位姿下的摆片基片特征尺寸测量重复性精度优于8μm。相较于工具显微镜,测量结果可靠性及重复性均有所改善,测量效率显著提升。     

一种石英挠性加速度计表头参数辨识方法研究

由于石英挠性加速度计表头参数理论值与实际值不一致,会影响加速度计的一些性能指标。为了获得石英挠性加速度计正常工作下的实际表头参数,研究了采用电激励法测试加速度计系统的闭环幅频特性,在幅频特性测试数据的基础上,运用MATLAB中的最小二乘曲线拟合方法编制程序辨识出石英挠性加速度计表头的3个参数。结果表明,这种方法简单可行,具有很大的实用性。     

An integrated CAE system for dynamic stress and fatigue life prediction of mechanical systems

This paper presents computer simulation methodology for dynamic stress time history computation to predict the fatigue life of machine components using flexible multi-body dynamics. A hybrid method which employes stress superposition as a function of constraint loads and component accelerations that are predicted by flexible body dynamic simulation is utilized and implemented using established codes. A system integration methodology for dynamic stress computation of mechanical system components is described to provide a usable environment for an engineer. It uses a database management system such as the IAC and the established dynamics and finite element analysis codes.     

柔性机器人的动态应力计算及疲劳特性分析

为了描述柔性机器人的动态应力状况和疲劳特性,将柔性机器人的动态应力计算与疲劳特性分析相结合,形成一种柔性机器人动态应力疲劳分析方法。分析了柔性机器人杆件的弹性变形与弹性位移的关系,计算了杆件的弹性变形及动态应力,通过计算杆件动态应力造成的疲劳损伤,预测其疲劳寿命,并根据疲劳强度计算杆件的工作安全系数。以柔性平面3-RRR并联机器人为例,说明杆件的动态应力计算和疲劳特性分析对动力学分析和设计的重要意义。     

The mechanism of ductile chip formation in cutting of brittle materials

A theoretical analysis for the mechanism of ductile chip formation in the cutting of brittle materials is presented in this paper. The coexisting crack propagation and dislocation in the chip formation zone in the cutting of ductile materials are examined based on an analysis of the geometry and forces in the cutting region, both on Taylor’s dislocation hardening theory and the strain gradient plasticity theory. It was found that the ductile chip formation was a result of large compressive stress and shear stress in the chip formation zone, which shields the growth of pre-existing flaws by suppressing the stress intensity factor K _I . Additionally, ductile chip formation in the cutting of brittle materials can result from the enhancement of material yield strength in the chip formation zone. The large compressive stress can be generated in the chip formation zone with two conditions. The first condition is associated with a small, undeformed chip thickness, while the second is related to the undeformed chip thickness being smaller than the radius of the tool cutting edge. The analysis also shows that the thrust force F _t is much larger than the cutting force F _c . This indicates that large compressive stress is generated in the chip formation zone. This also confirms that the ductile chip formation is a result of large compressive stress in the chip formation zone, which shields the growth of pre-existing flaws in the material by suppressing the stress intensity factor K _I . The enhancement of material yield strength can be provided by dislocation hardening and strain gradient at the mesoscale, such that the workpiece material can undertake the large cutting stresses in the chip formation zone without fracture. Experiments for ductile cutting of tungsten carbide are conducted. The results show that ductile chip formation can be achieved as the undeformed chip thickness is small enough, as well as the undeformed chip thickness is smaller than the tool cutting edge radius.     

直线超声电机柔性夹持元件的设计

设计了一种带有柔性铰链的直线超声电机夹持元件,夹持元件的两边和中间带有圆弧柔性铰链。两边的柔性铰链起弹簧作用,以便施加合适的预压力;中间的柔性铰链能够消除定子装配中的附加应力,减小定子装配对定子振动模态的影响。利用有限元方法分析了柔性铰链的变形量与预压力的关系。实验结果表明,直线超声电机夹框的位移与预压力成线性关系,并与有限元计算结果一致。柔性夹持元件装配的定子没有干扰模态,两相模态一致性好,并具有线性的边界条件。     

基于刚柔耦合系统的人体外骨骼研究

人体外骨骼结构由整体刚性部件和众多液压作动筒组成,为使人体外骨骼具有更好的减震和缓冲功能,在外骨骼结构中还增加了许多弹性阻尼部件。将整个人体外骨骼结构视为刚性部件与众多柔性部件的耦合结构。以60 kg为负重载荷,在ANSYS中创造性地利用刚柔耦合方式建立人体外骨骼结构有限元模型,并分析该外骨骼结构在行走过程中的受力情况和振动模态,获得各姿态应力值及各阶振型、自振频率。经分析得,外骨骼结构除踝关节结构需加强外,其余部件满足静力学强度要求,模态分析结果显示该外骨骼结构避开了人体运动时前后摆动的频率,但易于在左右摆动时产生共振。     

基于有限元模拟的高速切削中切削热的研究

基于有限元分析软件DEFORM-2D建立了典型的正交切削模型,模拟分析后得到切屑厚度、刀—屑接触长度和X、Y方向切削分力等参数值;结合剪切面及前刀面接触区的平均温度和切削热解析法,研究了高速切削中切削热在切屑、工件和刀具部分的量化分配规律。     

弹载SAR伺服控制焊点故障分析

针对弹载SAR伺服控制板焊点脱落故障,从整机随机振动加速度响应,单板级热应力和随机振动应力分析排查故障原因,根据仿真结果提出工艺参数优化和设计改进建议。仿真结果表明,伺服控制板的加速度响应是基础激励的1.78倍;金属陶瓷芯片采用表面贴装工艺组装时对热应力敏感,增加焊料厚度有利于降低热应力;带引脚芯片采用堆焊工艺时对振动应力敏感,在芯片与印制板之间点胶有利于降低振动应力。     

A linear viscoelastic relaxation-contact model of a flat fractal surface: a Maxwell-type medium

In this paper a hybrid virtual prototype is developed for analyzing the stress applied on cable shovel components by integrating flexible bodies into rigid multi-body model. The general mechanical system of the cable shovel is modeled as a seven-bar linkage with four degrees of freedom. The relevant theories applied for the dynamic model are described in terms of Lagrangian dynamics equation. The flexible body stress related to the body deformation is obtained by the dynamic equilibrium equation for a structural component based on the finite element method. A P&H 4100A cable shovel is used to validate the hybrid virtual prototype by loading the motions and loads on the model. Von Mises stress distributions of the boom, handle, hoist rope and sheave are visualized during cable shovel operation 3 sec. The results show that a high stress field is around the hoist rope. The maximum stress of 313.31 MPa occurs at node 441. By comparing the simulation results with reliability analysis results, the former is found to match well with the latter. Attention of this study is devoted to the mechanisms of damage of the cable shovel and also the critical high stress areas.     

FINITE ELEMENT ANALYSIS OF CHIP FORMATION IN GROOVED TOOL METAL CUTTING

Abstract

This paper presents the simulation of chip formation in grooved tool cutting using DYNA3D, 3D FEM software for dynamic nonlinear analysis that was used to simulate the orthogonal cutting problem. First, a flat-face cutting tool was employed in the simulation to verify the validity of the FEM model. Next, the same simulation techniques were used to study the effects of different groove geometries on the chip formation process in grooved tool cutting. In the first set of grooved tool simulations, the depth of the groove was constant while the width was decreased. In the second set, the width was constant and the depth was increased. By analyzing the chip flow, chip curl, chip thickness, stress and strain in the chip, the effects of different groove widths and depths on the chip formation process were then discussed.     

FINITE ELEMENT ANALYSIS OF CHIP FORMATION IN GROOVED TOOL METAL CUTTING

This paper presents the simulation of chip formation in grooved tool cutting using DYNA3D, 3D FEM software for dynamic nonlinear analysis that was used to simulate the orthogonal cutting problem. First, a flat-face cutting tool was employed in the simulation to verify the validity of the FEM model. Next, the same simulation techniques were used to study the effects of different groove geometries on the chip formation process in grooved tool cutting. In the first set of grooved tool simulations, the depth of the groove was constant while the width was decreased. In the second set, the width was constant and the depth was increased. By analyzing the chip flow, chip curl, chip thickness, stress and strain in the chip, the effects of different groove widths and depths on the chip formation process were then discussed.