Studies in dynamic design of drilling machine using updated finite element models

The aim of the present work is to develop updated FE models of a drilling machine using analytical and experimental results. These updated FE models have been used to predict the effect of structural dynamic modifications on vibration characteristics of the drilling machine. Two studies have been carried out on the machine. In the first study, modal tests have been carried out on a drilling machine using instrumented impact hammer. Modal identification has been done using global method of modal identification. For analytical FE modeling of the machine, a computer program has been developed. The results obtained using FEM, have been correlated with the experimental ones using mode shape comparison and MAC values. Analytical FE model has been updated, with the help of a program, which has been developed using direct methods of model updating. In the second study, modal testing has been carried out using random noise generator and modal exciter. Global method has been used for modal identification. Analytical FE modeling has been done using I-DEAS software. Correlation of FE results with the experimental ones has been carried out using FEMtools software. Updating of the analytical FE model has also been done using the above software, based on an indirect technique viz. sensitivity based parameter estimation technique. The updated FE models, obtained from both the studies have been used for structural dynamic modifications (SDM), for the purpose of dynamic design and the results of SDM predictions are seen to be reasonably satisfactory.     

A、C双摆头型五轴机床工作精度检验方法研究

结合NAS979圆锥台试件对A、C双摆头型五轴机床工作精度检验方法进行了研究。制定了包括装夹方法、刀具、切削参数在内的加工工艺;运用NX8.0软件生成了刀具轨迹;基于NX8.0构建了适用于西门子840D系统的A、C双摆头型五轴机床后置处理器,利用其生成了加工程序;用VERICUT软件对加工程序进行了仿真;对试件进行了实际加工与检测,精度合格。通过研究总结出了用NAS979圆锥台试件对A、C双摆头型五轴机床进行工作精度检验的方法。     

单片机在车削细长轴误差补偿时的应用

建立了有跟刀架情况下的细长轴车削力学模型,并用Deform软件对细长轴车削过程进行了有限元仿真,得出车削过程的刀具磨损值;解释了由切削力引起的工件退让和刀具磨损是细长轴加工的主要误差来源;采用单片机对车削过程的误差进行了补偿,达到了抑制尺寸误差的目的.     

回转柜药房机械结构设计与分析

以药房自动化需求为基础,设计出了一套半自动药房机械。计算出了轴承的径向刚度,为有限元计算提供参数,并运用COSMOSWorks有限元分析软件对整机进行静力学分析和模态分析。静力学分析识别出了结构的最大应力点和最大变形位置;模态分析计算出了结构的前六阶固有频率和相应的振型,结合外界激励频率对结构动态特性作出了客观评价。在有限元分析结果基础上,对整机结构进行了优化,达到了结构整体受力均匀、重量轻、刚度高的目的,提高了整机的动态特性。     

实用化振动切削技术——总论

振动切削技术历经半个世纪的发展，逐步揭示了振动切削的机理，形成了振动切削理论体系。同时，在大量工艺试验研究的基础上，得到了大量的工艺效果并研制出了各种振动切削装备，逐步使振动切削技术走向实用化。     

履带车辆动力传动系统扭振的时域仿真研究

对某型履带车辆的动力传动系统扭振进行了仿真建模。针对动力传动系统中具有非线性特征的液力变矩器和盖斯林格联轴器等部件，建立了相应的非线性时域仿真模型，同时建立了发动机激励模型。将系统仿真得到的时域结果进行分析，并与实验数据进行了验证比较，仿真结果与实验数据较吻合。     

由拉伸试样确定材料真实应力应变关系

提出一种借助有限元分析由光滑和切口圆棒试验数据确定应力应变关系的方法，首先分析光谱和切口圆棒，得到其各自的应力应变分布，研究在颈部应力应变随变形位移和材料的分布变化，得到其间关系的曲线图，同时对圆棒颈缩变形进行模拟。对工程上常用的硬化指数差别较大的两种钢材制成的光滑试样及切口试样进行初步的计算与分析，对影响拉伸试样颈缩形成的因素进行研究，指出试样夹持端状态与外廓直径的细微减少及加载约束方式三者对颈缩有重要影响，对工程上常用的bridgeman估算公式进行分析，指出其在工程上的适用性。     

汽车轮毂轴承模拟试验技术

介绍了LGM-15/45汽车轮毂轴承模拟试验机，对富康轿车前轮毂轴承及桑塔纳轿车后轮毂轴承进行模拟试验。并对桑塔纳轿车在运行过程中轴承出现的微动磨损现象进行了故障再现，探索了微动磨损的试验方法。开展了桑塔纳轿车前轮毂轴承喷泥砂试验，制定了试验规范和评判标准。     

On the qualitative analysis of nonlinear resonant modes in multidimensional structures

The resonant behavior of multidimensional structures simulated via strongly nonlinear dynamic systems has been studied. The energy balance principle has been applied for the qualitative analysis of these systems. The number of potential nonlinear resonant modes under periodic polyharmonic force and parametric excitation has been estimated. The dynamic effects have been investigated and examples have been provided.     

Flow-forming and flow formability simulation

Forward flow forming of tubes have been simulated using an explicit commercial finite element program. Variation of contact geometry considering plastic flow has been calculated based on the proposed criterion. Also flow formability of tube materials have been calculated during forward flow-forming process. Contact geometry simulation results as the variation of S-to-L ratios with feed rates and two attack angles have been compared with outcomes of geometrically based equations. The effects of attack angles and feed rates on the flow formability have been also evaluated. The simulation results have been compared with existing experimental results and validities of outcomes have been shown.     

基于有限元法对CCD刀具预调测量仪机械结构的分析与优化

运用专业有限元软件对新开发的CCD刀具预调测量仪的底座和立柱进行有限元分析与计算,研究其在公称力下底座和立柱的变形和应力分布情况,并分析构成底座结构主要部件对机身应力应变的影响.根据分析结果,对机身结构进行了优化设计,在保证机身刚度的情况下,进一步减轻机身重量,降低生产成本,提高了产品的竞争力.     

空调压缩机用冲压外圈滚针轴承

着重分析空调压缩机采用新的环保型冷媒体后，常规结构滚针轴承的破坏情况，提出了冲压滚针轴承新的结构改进设计及其开发和性能比较结果，为今后新冷媒体空调压缩机的广泛使用，提供了有利的保证。     

光盘轴向机械动态特性测量方法的研究

研究了光盘轴向机械动态特性和聚焦伺服系统的关系，系统研究了影响光盘轴向偏摆各分量对总偏摆的影响，据此建立光盘轴向偏摆的数学模型。根据该模型，分析了几种有代表性的测量方法的优缺点并重点研究了它们各自的测量精度，提出了一种全新的基于激光三角法的测量方法。最后给出了测量结果和结果分析。     

五轴“S”型试件的编程、仿真与高速加工研究

主要研究了"S"型试件的加工工艺;基于NX8.0的"S"型试件五轴编程,刀具轨迹优化;构建了基于NX8.0的HEIDENHAIN iTNC 530系统A、C双摆台式机床的后置处理器,利用其生成NC程序;利用VERICUT软件进行了加工仿真;并最终对"S"型试件进行了实际加工和检测。     

The application of weak-beam imaging to studies of small dislocational loops

Coupled differential equations for calculating diffracted ands tranmitted intensities from thin crystals have been solved numerically for many beam diffracting conditions. This approach has been used to enable us to study weak-beam dark-field images from small circular edge dislocation loops. The exact displacement field around such loops has been calculated using isotropic elasticity theory. Crystal orientations have been chosen to obtain single systematic rows of low order reflections and loop images have been calculated for different combinations of strong and weak beams. Although emphasis has been placed on investigating the application of weak beam imaging to determine the nature of small loops (diam. < 10 nm) a preliminary study has also been made of g.b = 0 residual images. The calculated images have been compared with experimental weak beam images of small loops in neutron irradiated molybdenum.     

轴承浪形保持架冲孔模退料环的工艺改进

改进前工艺是12道工序，改进后工艺是10道工序。工艺改进后小孔中心距公差尺寸达到0．02mm以内，保证退料环质量，提高了生产效率。     

新型高摩擦式防滑差速器的运动几何分析

介绍一种新型高摩擦式防滑差速器的结构,并较详细地论述该差速器的运动学和动力学特性,分析它的动力传递路线和工作原理,推导出锁紧系数K,同时,剖析该差速器锁紧系数的调节原理。     

M7120型平面磨床主轴轴承静压改造

通过对M7120型平面磨床主轴轴承的静压改造,克服了原结构的不足,提高了主轴系统的刚度,增大了承载力,同时降低了主轴系统的故障率。     

Closed-form solution of axisymmetric contact problem for a viscoelastic base within cycle of increasing and decreasing of load on the indenter

The axisymmetric contact problem for a spherical indenter and viscoelastic base has been considered within a cycle of increasing and decreasing of load. The loading-unloading cycle has been performed at a constant speed of indenter movment. The quasi-static approximation has been used. The study has been carried out according to linear viscoelasticity theory, while the material model allows one to take into account an arbitrary number of relaxation times. The dependence of load on the indenter on time has been defined. Expressions for determining the unknown boundary of the contact area in the loading–unloading process has been given. The hysteretic loop area at different values of the material relaxation time has been analyzed. The applicability of the offered analytical model of elastomer indentation experiments data processing has been discussed.     

Pure plastic bending of sheet laminates under plane strain condition

Pure plastic bending of two- and three-ply laminates in plane strain condition has been investigated. Rigid-strain hardening material behavior has been assumed. For fibers which have been overtaken by the neutral axis and have experienced load reversal, a linear $\text{}\text{?}$gs ? $\text{}\text{?}$ge relationship has been adopted. Different deformation zones have been recognized and relevant equations for the distributions of radial and tangential stresses in terms of material parameters and unknown variables have been determined. In each case, from continuity of radial stress at interlaminate boundaries, an expression for the current location of the neutral axis, in terms of the relative curvature, χ, and the relative thickness, η, has been obtained. A numerical scheme for the simultaneous solution of this expression, along with a thickness equation, has been developed. As a result, distributions of radial and tangential stresses, fiber movements, and bending moments have been calculated.The effect of material properties in terms of core/clad strength differential, and rate of strain hardening has been determined. Also, the influence of laminate geometry in two-ply, as well as symmetric and non-symmetric three-ply laminates, has been investigated.