机械装配动态质量的子结构分析与量化计算

机械装配作为机电产品生产制造的重要工艺,直接影响产品整体动态质量。现有机械装配质量检测分析主要集中在"静态质量",如尺寸协调性与形位公差等,而机械装配本身还具有动态质量,机械装配检测评价只关注其静态质量有失全面。在诠释"机械装配动态质量"的概念之后,基于子结构分析方法明确界定了机械装配动态传递特性函数关系,并采用本征值分析方法讨论了机械装配工艺对装配子结构部件和装配件系统的动态传递特性的影响作用。进而采用测量的频率响应函数(frequency response function,FRF)计算机械装配比率矩阵的本征值,并用其均值对机械装配动态质量进行量化计算。基于两部件机械装配的"二级子结构"集总参数模型和应用实例模型,检验了相关分析结论和所建立的量化计算方法。研究结果有助于完善现有机械装配质量检测评价技术理论。     

基于FRF的螺栓结合部动力学问题的研究

螺栓联接是机床结合部的重要形式之一,其动力学特性对机床动态特性影响显著。从子结构综合的思想出发,通过FRF法建立了螺栓联接结合部动力学的理论模型,并基于力学平衡方程和位移兼容方程,推导了结合部动刚度的辨识方程;进而,基于最小二乘法提出了结合部动刚度的等效计算方法;最后,规划了基于LMS振动测试环境的动力学试验,测试结果显示:有限元预测值与试验实测值之间一致度良好,验证了方法的可行性。     

微机电陀螺耦合刚度的辨识

针对微机电陀螺耦合刚度的辨识,提出了以驱动轴、检测轴、驱动-转动耦合和驱动-检测耦合频率响应特性为基础的耦合刚度辨识方法。设计了一种驱动轴和检测轴双向位移解耦的双质量线振动微机电陀螺,基于经过简化的梁的刚度特性建立了微陀螺平面运动动力学方程,导出了结构在存在耦合刚度情况下驱动轴、检测轴、驱动-转动耦合和驱动-检测耦合的传递函数。根据耦合传递函数把刚度耦合产生的根源定位到特定的几组梁之间的刚度误差。通过驱动-转动耦合与驱动轴幅频特性之比辨识出驱动-转动耦合刚度系数,通过驱动-检测耦合与检测轴幅频特性之比辨识出转动-检测耦合刚度系数。实验测试了设计加工的微陀螺的频率响应特性,利用提出的耦合刚度辨识方法得到陀螺的驱动-转动和转动-检测耦合刚度系数分别为0.14N和0.054 33N。得到的耦合刚度的辨识结果可为微陀螺梁刚度的激光修调提供参数依据。     

高速高精运动平台谐振分析与抑制研究

针对直线电机直接驱动的高速高精运动平台的谐振问题,对高速高精运动平台的控制系统模型、伺服动刚度模型、移动部件质量、在线辨识算法和积分谐振控制(IRC)谐振抑制方法等内容进行了研究,提出了一种基于递推最小二乘辨识算法在线辨识谐振模型以及IRC抑制谐振的控制方案,构建了高速高精运动平台伺服控制系统模型和伺服动刚度模型,在仿真模型的基础上研究了移动部件质量的变化对系统伺服动刚度的影响,考虑控制系统伺服动刚度对谐振的影响,利用在线辨识算法获取到的谐振模型参数设计了IRC抑制系统谐振。研究结果表明,该控制方案对系统伺服动刚度不足造成的谐振现象具有较好的抑制效果,能大大提高系统动态性能。     

7500t浮式起重机金属结构的动态优化设计

采用动态子结构方法在有限元平台上建立了7 500t浮式起重机的动力学模型,应用动态分层优化方法进行整体层和局部层的动态优化.在整体层,实现整体结构的尺寸参数优化,提高臂架在起升平面内弯曲模态的固有频率;在局部层,实现关键子结构的截面参数优化,改善关键子结构的动刚度.通过动态优化设计,有效改善了7 500t浮式起重机金属结构的动态特性,提高了其主要模态的动刚度.     

机床结合部动力学建模与辨识方法的研究

针对机床结合部动力学建模与辨识过程中对子结构间耦合关系与内部激振对外部响应影响考虑不充分问题,采用频响函数矩阵建立完备的机床结合部动力学理论模型;基于力学平衡条件和位移兼容条件推导了辨识方程,提出一种新的动力学辨识方法;辨识过程中融入了子结构间耦合关系,将难测频响矩阵作为中间变量抵消,避免使用难以测量频响或估算难以测量频响所引入的方程误差。在此基础上,将辨识方程拓展至整个测量频段,构建包含辨识关系的矛盾方程,通过最小二乘法求解确定了结合部的等效动刚度,建立了结构的有限元模型。为验证方法的正确性与可行性,基于LMS试验平台进行了现场试验,获得了良好的试验效果;与缩减维度、忽略内部激振作用的建模方法进行了对比分析,结果表明本文方法具有更好的预测性。     

基于压缩频响函数的结构损伤识别

结构的损伤识别可作为一个优化问题来处理。本文直接应用频响函数(FRF)进行结构的损伤识别。通过对FRF的主成分分析(PCA)实现数据压缩和特征提取,建立基于压缩FRF的优化目标函数。为了提高算法的收敛速度,以结合局部搜索算法(LS)的遗传算法(GA)为优化工具,并进一步结合子结构识别法来求解。基于桁架的计算结果表明,这种方法具有很好的鲁棒性和识别效果。     

车削加工过程中轴类工件频响函数的快速预测

轴类工件在车削加工过程中由于材料去除,其动力学特性会实时变化。快速准确预测工件频响函数是构建车削稳定性极限图,防止车削颤振的关键环节。通过分析轴类工件连接界面的变形特性,发现刚性耦合条件下的频响耦合子结构法在预测轴类工件频响函数时具有局限性。在此基础上,考虑连接界面刚度影响因素,推导出连接界面刚度的计算方法,利用柔性耦合条件下的频响耦合子结构法建立了加工过程中轴类工件频响函数求解快速预测模型。试验与理论分析结果表明:柔性耦合模型能够快速准确地预测轴类工件随材料去除时的频响函数变化;与刚性耦合模型相比,柔性耦合模型对频响函数预测的准确性受工件尺寸变化影响较小,模型应用范围更广。     

基于子结构法的齿轮箱-基座耦合系统结构振动仿真研究

为了提高齿轮箱-基座耦合系统结构振动分析的计算效率,采用子结构法提取了基座在与齿轮箱各连接点处的等效质量和等效刚度,并用质量单元和刚度单元对基座进行了等效。在此基础上建立了齿轮箱-基座耦合系统的结构振动分析模型,完成了齿轮箱-基座耦合系统的结构振动分析,并与全有限元法的分析结果进行了对比。结果表明:采用子结构法分析获得的齿轮箱-基座耦合系统在各连接点处的有效加速度级与全有限元法分析结果间的差距均未超过3dB,同时子结构法的分析时间仅为全有限元法的38. 5%。     

基于转移质量方式的龙门加工中心动横梁结构优化设计方法

针对某大型龙门加工中心动横梁结构设计中存在一些部位材料余量过大、一些部位刚度不足的问题,提出一种以转移质量为核心的动横梁结构优化设计方法.方法是在对动横梁进行动静态性能分析的基础上,利用模态分析和拓扑优化技术辨识动横梁结构中的冗余质量,并将其转移到动横梁刚度不足的薄弱位置,设计出在不改变动横梁装配尺寸的前提下具有较为均衡动静刚度特性的动横梁结构方案.通过对改进前后动横梁结构的动静态性能参数的分析对比,改进后动横梁前4阶固有频率平均提高5.53％,整体方向最大变形量平均减少7.33％,表明该结构优化方法是有效可行的.     

Analysis and inverse substructuring computation on dynamic quality of mechanical assembly

Mechanical assembly has its own dynamic quality directly affecting the dynamic quality of whole product and should be considered in quality inspection and estimation of mechanical assembly. Based on functional relations between dynamic characteristics involved in mechanical assembly, the effects of assembling process on dynamic characteristics of substructural components of an assembly system are investigated by substructuring analysis. Assembly-coupling dynamic stiffness is clarified as the dominant factor of the effects and can be used as a quantitative measure of assembly dynamic quality. Two computational schemes using frequency response functions(FRFs) to determine the stiffness are provided and discussed by inverse substructuring analysis, including their applicable conditions and implementation procedure in application. Eigenvalue analysis on matrix-ratios of FRFs before and after assembling is employed and well validates the analytical outcomes and the schemes via both a lumped-parameter model and its analogic experimental counterpart. Applying the two schemes to inspect the dynamic quality provides the message of dynamic performance of the assembly system, and therefore improves conventional quality inspection and estimation of mechanical assembly in completeness.     

面向过程的虚拟环境中产品装配建模研究

提出了面向过程的虚拟装配建模方法,在虚拟环境中将装配建模与装配仿真相结合,建立装配关系模型的同时,实现了对装配过程的创建与仿真,从而,在虚拟环境中将面向结果的装配建模发展为面向过程的装配建模.设计者采用直接三维交互进行装配建模操作的同时,系统通过装配关系识别自动捕捉设计者的装配设计意图,通过装配约束运动确定零件的装配路径,通过虚拟装配建模过程信息重用为装配规划提供有效的支持.开发了面向过程的虚拟装配建模原型系统.实践表明,面向过程的虚拟环境中产品装配建模方法有效地提高了产品装配设计的质量与效率.     

Construction of orthogonal projector for the damage identification by measured substructural flexibility

The substructuring methods have been popularly used in model updating, system identification and damage assessment. In the substructuring methods, the global structure is divided into free–free substructures. The independent substructures move freely, and their stiffness matrix is singular and rank-deficient. The flexibility matrix of the free–free substructure, which is associated with the inverse of the stiffness matrix, is not easy to be determined. This study expands on the previous research of the substructuring methods by taking a deeper look at the analysis of a free–free substructure. An orthogonal projector is formulated to add/remove the rigid body components from the generalized stiffness and flexibility matrices of a free–free substructure, and thus make the substructural flexibility useful to model updating or damage identification. The orthogonal projector is derived both for the full and partial measured flexibility, and it can remove all rigid body components regardless its participation factor. The accuracy of the proposed method in extraction of the free–free flexibility and in damage identification is verified by an experimental beam. The properties addressed in this paper are not limited to be used for the analysis of a free–free substructure in many substructuring methods, and they are promising to be generalized to a range of analysis relevant to a free–free structure.     

在EMPOWER中实现雷达的虚拟装配

虚拟装配技术是虚拟制造技术在设计和制造业中的重要应用领域之一。文中阐述了虚拟装配的原理和过程,以雷达产品中的天线座系统为对象,对其装配顺序进行规划,实况装配零件和部件,实现装配过程仿真。为虚拟装配技术在雷达产品中的应用做了初步的尝试和探索。     

Active variation compensation in vehicle body conceptual assembly

In this paper, an intelligent heuristic optimization algorithm in active variation compensation is proposed to improve the dimension accuracy in the assembly of a vehicle body by finding the optimal configuration of joint types and the corresponding assembly sequence to compensate variation accumulation in the conceptual assembly process. The authors develop and apply the algorithm to predict variation accumulation and then develop compensating assembly schemes to accomplish optimal joint configuration and assembly sequence compensating for the unnecessary or surplus variation. The essence of the active variation compensation algorithm means measuring and correcting assembling variations during the assembly conceptual process. The paper employs the design of experiment (DOE) approach to verify the heuristic optimization method in the simple application case.     

Identification of dynamic stiffness matrix of bearing joint region

The paper proposes an identification method of the dynamic stiffness matrix of a bearing joint region on the basis of theoretical analysis and experiments. The author deduces an identification model of the dynamic stiffness matrix from the synthetic substructure method. The dynamic stiffness matrix of the bearing joint region can be identified by measuring the matrix of frequency response function (FRFs) of the substructure (axle) and whole structure (assembly of the axle, bearing, and bearing housing) in different positions. Considering difficulty in measuring angular displacement, applying moment, and directly measuring relevant FRFs of rotational degree of freedom, the author employs an accurately calibrated finite element model of the unconstrained structure for indirect estimation. With experiments and simulation analysis, FRFs related with translational degree of freedom, which is estimated through the finite element model, agrees with experimental results, and there is very high reliability in the identified dynamic stiffness matrix of the bearing joint region.     

精益六西格玛在机械修理装配质量控制中的应用

精益六西格玛是精益思想与六西格玛管理方法的有机结合,其本质是消除浪费和降低变异。通过对WD-400挖掘机大修厂滑动轴承的装配修理工序进行分析,阐述了精益六西格玛DMAICⅡ模型在装配质量控制中应用的整个实施过程,利用Minitab软件对质量数据进行分析,找出了影响装配质量的关键因素——装配方法、装前检验和清洁润滑,并针对每一个关键因素探索了控制措施。结果表明,在机械修理装配质量控制中应用精益六西格玛是可行的。     

Quality assurance model in mechanical assembly

The uncertainty of mechanical assembly process usually brings great challenge to product quality control and assurance. The systematic approach should be employed in the research to find a comprehensive solution. The quality assurance model for assembly (QAMA), based on the analysis of the major problems in the mechanical assembly process and the factors that affect the quality of products, is established by means of three working models: the assembly process model (APM), the activity control model (ACM), and the quality data model (QDM). The APM formulates the assembly process starting with the analysis of process flow, logical scheme, and key factors. The ACM is built by defining the attributes of control activity, mapping relationship between the control activities and its objects in the multiview space and layers. The ACM presents the control flow with the logical relations among control activities as well as the control rules. Based on the two models mentioned above, the QDM supports the acquisition of quality data through data-collecting carriers along assembly process and defines the data structure to support the system model. All of the three models are grouped into a framework which integrates the technical approaches and solutions for quality assurance in mechanical assembly. Based on modeling studies, a computer-integrated and internet-based system called quality assurance system in mechanical assembly (QAS/MA) has been developed. And the development of QAS/MA proves that APM, ACM, QDM, and QAMA are practical and feasible.     

虚拟装配在装甲车辆行业的应用研究

以打造"数字化兵器"为契机,推进交互式虚拟装配在装甲车辆行业中的研究、推广应用。主要从虚拟装配的概念、装配过程仿真介绍、虚拟装配行业背景和应用情况、虚拟装配构成和企业实施途径、虚拟装配对装甲车军工企业的指导意义几个方面进行了阐述。通过虚拟装配的应用学习,促进数字化设计、数字化制造、数字化管理在装甲车辆军工企业的全面推广应用。     

基于ANSYS/LS-DYNA钻削过程的数值仿真

制孔工序是飞机结构装配中一个非常重要的环节。根据飞机薄壁结构零件钻孔工序,建立麻花钻钻削加工过程有限元仿真模型,采用通用显式动力分析程序LS-DYNA对钻削加工过程进行三维数值仿真研究。仿真动态模拟了钻削加工时钻屑和毛刺的生成过程,获得了螺旋钻屑;提取并分析了钻削轴向钻削力特征;采用直接热力耦合有限元方法分析了加工过程中刀具和工件间摩擦热的产生及钻削温度的瞬态分布。仿真结果表明,钻削毛刺在钻入和钻出都有可能产生,且钻出毛刺大于钻入毛刺。仿真得到的轴向钻削力与理论相符。