Structural optimization of typical rigid links in a parallel kinematic machine

The motion dynamics and accuracy of parallel kinematic machines largely depend on the weights and rigidity of typical rigid links. Therefore, these parts should be designed in such a way that they are light but rigid. This work employs the techniques of topology and size optimization to design two typical rigid links of a parallel kinematic machine (PKM) and subsequently obtains applicable structures for them. The calculation models are established, and a new algorithm called the Guide-Weight method is introduced to solve topology optimization problems. The commercial software Ansys is used to perform size optimization.     

可重构技术在高速精密卧式加工中心设计中的应用

结合大高速精密卧式加工中心的设计,针对金属切削机床的可重构技术进行了分析并提出了新的见解。在设计中采用模块化设计的理念,进行了机床的模块化设计,降低了同系列产品的设计难度,避免了重复性工作,提高了生产加工环节以及制造装配等环节的生产效率。     

基于状态构形矢量和状态构形矩阵的可重构模块星球机器人构形

可重构模块星球机器人系统由母体和多个子机器人模块组成,单个模块可以独立运动和操作,多个模块可以重构组合成不同构形,模块采用非对称式轮手一体机构,具有姿态方位性和运动方向性,重构目的是组成在某种环境下更好地完成有向性运动的构形。基于此,提出矢量构形概念,将运动趋势方向和方位性融合到构形拓扑结构中。在模块矢量分析模型基础上,提出并构建状态构形矢量(State configuration vector, SCV)和状态构形矩阵(State configuration matrix, SCM),对非对称式单模块和整体构形的状态信息进行描述,同时支持预定义的数学变换操作,可以表达并触发模块的基础动作、构形重构。提出离散模块组合重构成目标构形的优化分析算法,通过实例仿真计算获得优化分析的选择结果。     

Product modular design incorporating preventive maintenance issues

Traditional modular design methods lead to product maintenance problems, because the module form of a system is created according to either the function requirements or the manufacturing considerations. For solving these problems, a new modular design method is proposed with the considerations of not only the traditional function related attributes, but also the maintenance related ones. First, modularity parameters and modularity scenarios for product modularity are defined. Then the reliability and economic assessment models of product modularity strategies are formulated with the introduction of the effective working age of modules. A mathematical model used to evaluate the difference among the modules of the product so that the optimal module of the product can be established. After that, a multi-objective optimization problem based on metrics for preventive maintenance interval different degrees and preventive maintenance economics is formulated for modular optimization. Multi-objective GA is utilized to rapidly approximate the Pareto set of optimal modularity strategy trade-offs between preventive maintenance cost and preventive maintenance interval difference degree. Finally, a coordinate CNC boring machine is adopted to depict the process of product modularity. In addition, two factorial design experiments based on the modularity parameters are constructed and analyzed. These experiments investigate the impacts of these parameters on the optimal modularity strategies and the structure of module. The research proposes a new modular design method, which may help to improve the maintainability of product in modular design.     

分布式柔性机构拓扑优化设计的理论和算法

将连续体结构的拓扑优化技术应用到分布式柔性机构的设计中,基于变密度法和优化准则法推导并建立柔性机构拓扑优化的一种显式的设计变量收敛格式。结合分布式柔性机构优化设计的人工弹簧模型和虚拟载荷法,提出一种新型的分布式柔性机构拓扑优化设计的多准则优化模型,同时综合考虑柔性机构设计的机械效率要求和结构的刚度要求,并利用伴随敏度分析法进行敏度分析。数值算例证明研究方法的有效性,并分析和讨论优化模型和收敛格式中有关优化设计参数对柔性机构优化设计结果的影响。用激光快速成形技术验证柔性机构概念设计的合理性。     

可重构单元模块化及其结合面动特性的研究

通过对可重构制造系统(RMS)关键技术的研究，分析讨论了单元模块化对RMS的重要意义，指出了模块化设计在具体实现过程中存在的问题。给出了可重构制造单元模块的定义以及阐明了最小运动模块的具体划分。为管理、配置模块，给出了模块的组合数学模型，这有助于模块分类、排列以及组合。根据模块组合数学模型，总结出可重构单元模块接口即结合面的特点。运用分形技术，对模块结合面接触刚度的研究，得到了重构后结合面表面粗糙度与分形维数的关系原型以及接触刚度，为研究模块重构后形成的装备的动态特性、精度以及可靠性奠定基础。     

传热结构自适应拓扑优化准则法研究

合理的散热通道分布是提高小空间大热流密度传热结构散热性能最有效的手段。针对现有传热结构拓扑优化设计结果形态过于复杂,存在棋盘格、灰度单元等数值不稳定现象,提出一种基于基结构的散热通道分布的自适应拓扑优化方法。研究了适用于传热结构拓扑优化问题的基结构构建技术,建立满足库恩-塔克（Kuhn-Tucker,KKT）最优准则条件的迭代公式;以散热弱度最小为优化目标,以杆单元截面积为设计变量,对典型的二维和三维设计问题进行散热通道分布设计,并将设计结果与COMSOL软件优化结果进行对比。研究结果表明,提出的传热结构自适应拓扑优化方法产生的散热通道形态简单清晰,能满足散热性能,且优化过程收敛速度快,克服了现有优化方法产生的数值不稳定问题。     

轴系的模块化建模方法

根据轴系是由一些典型结构组合而成的特点,提出一种轴系的模块化建模方法。讨论了轴系的模块划分规则和步骤以及模块的两种组合原理,并以圆锥齿轮悬臂支撑结构轴系为例验证了方法的有效性。     

基于创成设计思想的可重构机床模块设置方法

建立合理的功能模块群是实现可重构机床方案重构的关键,基于创成设计方法建立了以镗铣加工为主的机床结构形态方案图谱,解决了机床模块划分时机床结构形态方案不足的问题。通过对机床结构形态方案的分析,划分出机床概念结构模块群;依据可重构机床模块功能自治原则,建立了机床概念功能模块群;将机床的概念功能模块、运动功能及被加工零件的工艺方案联系起来,建立了以工艺方案为依据的可重构机床功能模块群设置方法,并以某变速箱壳体件加工为例验证了该方法的可行性。     

多臂节机械臂架系统连杆组参数化建模及优化设计

针对多臂节机械臂架系统连杆计算效率不高,优化设计手段保守的问题,以混凝土泵车臂架作为典型工程装备部件,将臂节之间的油缸及连杆作为整体考虑成连杆组,利用ANSYS APDL语言对连杆组进行参数化建模,并在多工况下进行优化分析,得到连杆组的最优结构模型;通过结构应力试验,验证了计算方法的可行性.结果表明,参数化建模及优化设...     

Module-based method for design and analysis of reconfigurable parallel robots

This paper presents a method for the design and analysis of reconfigurable parallel robots. The inherent modularity in a parallel robot lends itself as a natural candidate for reconfiguration. By taking the branches as building blocks, many modular parallel robots can be constructed, from which a reconfigurable parallel robot can be realized. Among three types of reconfigurations, namely, geometry morphing, topology morphing, and group morphing, the method presented here is for the last two reconfigurations, thereby advancing the current research that is mainly limited to geometry morphing. It is shown that the module-based method not only provides a systematic way of designing a reconfigurable parallel robot, but also offers a unified modeling for robot analysis. Two examples are provided, one showing the topology morphing and the other showing the group morphing.     

基于应变能和拓扑描述数组的三维弹性体拓扑优化设计

提出一种基于应变能和拓扑描述数组的三维弹性体拓扑优化设计方法。该方法通过定义三维弹性体的拓扑描述数组实现了在拓扑优化设计的过程中单元网格的快速重新划分及结构拓扑信息的记录、设计域及非设计域的定义和单元的删除,将应变能低的单元定义为低效或无效的单元,在拓扑优化的过程逐步去除应变能低的单元获得结构的优化拓扑,该拓扑优化设计方法采用ANSYS软件的APDL语言实现。在程序设计中采用巧妙的增加应变能阈值的技术以避免设计灵敏度分析所带来巨大的计算工作量,从而提高了拓扑优化的效率,在整个拓扑优化设计过程中不需要人工控制的参数,程序通用性好。数值结果表明该方法高效简单,得到的最优拓扑符合工程结构的特点。     

考虑连接性的三明治阻尼复合结构拓扑优化设计

三明治阻尼复合结构的力学性能取决于阻尼层材料的性能,综合考虑该结构的阻尼性能和可制造性要求,提出了一种面向结构宏观性能并考虑连接性的三明治阻尼复合结构拓扑优化设计方法。以最大化结构模态阻尼比为目标,考虑微结构刚度相材料的连接性,通过组合强制性连接约束法和非线性扩散法,构建了连接性约束下的阻尼复合材料微结构的优化设计模型,并结合3D打印技术实现了三明治阻尼复合结构的制造。运用所提方法对典型结构进行优化设计,得到了刚度相保持连接的阻尼复合结构,且优化后的结构阻尼变大,结构的频率响应变小,实现了三明治阻尼复合结构材料结构设计制造协同优化设计。仿真和实验结果表明,在微结构上存在最优的阻尼材料体积分数使优化后的三明治结构频率响应最小。     

飞机蒙皮拉形模拓扑优化设计

将拓扑优化技术应用于大型飞机蒙皮拉形模的轻量化问题,可以解决传统拉形模设计中刚度与重量之间的矛盾。应用ABAQUS软件进行蒙皮拉形的非线性数值模拟,可以获取拉形模工作面的载荷数据。根据载荷数据选取的典型工况及给定的材料属性、约束条件等进行拓扑优化,将得到的拓扑优化结果进行模型重构,再对重构后的模型进行蒙皮拉形仿真,以验证模具的各项设计指标是否符合要求。以某型拉形模为例进行拓扑优化,并与传统设计的模具相比较,结果证明在同体分比的情况下,拓扑优化设计显著减小了模具的最大变形值和应力值。     

RESEARCH ON THE GENERALIZED MODULAR DESIGN METHOD WITH FLEXIBLE MODULES OF PRODUCT STRUCTURES

A new generalized modular design (GMD) method is proposed based on design practice of frame structure of hydraulic press machines. By building a series of flexible modules (FMs), design knowledge and structure features are integrated into parametric models. Then, parametric design and variational analysis methods for GMD are presented according to user defined design objectives and customized product characteristics. A FM-centered GMD system is developed and successfully used in the rapid design of relevant products.     

足式教学机器人的模块化设计

为了使教学机器人具有开放式、可重构的结构,以满足教学需求,根据模块化设计的原则对足式教学机器人进行了模块划分和模块化设计,使各模块构成的整体结构能协调运动,使之能适应不同的教学环境,完成多变的动作任务,激发学生的创造力以及对机器人知识的浓厚兴趣和热情。     

基于拓扑优化的机床立柱筋板改进

在拓扑优化的基础上,提出根据拓扑优化结果改进筋板布局的方法,并结合案例,构造了基于相对密度法的连续体结构动力学拓扑优化设计数学模型,以结构的相对密度为设计变量,分别以柔度最小化、一阶固有频率最大化为目标和两者结合的多目标进行拓扑优化。在采用多目标优化时,对两个目标用加权和方法进行折衷处理,通过设置权值来确定两者在优化中所起作用大小。优化后得出不同的密度云图,根据密度云图所示材料分部,改进筋板布局,达到提高机床动、静态特性的目的。     

含自重载荷的功能梯度材料结构时域动力学拓扑优化设计

提出了一种含自重载荷的功能梯度材料(FGM)结构时域动力学拓扑优化设计方法。在固体各向同性材料惩罚(SIMP)框架下,提出了一种针对FGM-SIMP的结构自重载荷分布策略。以FGM结构动柔度最小为优化目标、以结构体积为约束,建立了动力学结构优化列式。基于伴随法,在时域内进行了灵敏度推导,并用移动渐近线方法进行求解。通过二维和三维典型数值算例系统研究了含自重载荷下FGM结构的拓扑优化设计问题,并深入探讨了自重载荷和材料梯度分布方向对结构优化结果的影响,发现自重载荷和材料梯度分布方向对FGM结构的优化构型和动刚度具有很大影响。最后,以均一材料(FGM的特例)为例,通过数值仿真和实验测试方法验证了所提方法的有效性,并证实了所提方法可有效提高结构的固有频率和结构动刚度。     

模块化可重构机器人的构形在线自主辨识

针对模块化可重构机器人(Modular reconfigurable robot,MRR)构形复杂多变的特点,提出一种基于上层数据库和底层接口电路相结合的构形在线自主辨识方法。以所研制的MRR系统样机为研究对象,介绍关节、连杆、基座和夹爪等四类基本功能模块的结构及特殊接口电路设计;考虑多模块组合运动形式的等效性,以及同类型关节模块在输出力/力矩方面的差异,改进MRR构形空间的计算方法。利用图论中树的相关理论,在定义同类构形生成树和同序构形树枝的基础上,建立MRR构形辨识的总体研究模型,包括同类构形生成树辨识、同序构形树枝辨识和边约束条件辨识三个部分。根据模型中各部分的具体辨识对象,通过构建基本功能模块的上层数据库,并结合底层接口电路的特殊设计,实现机器人在无人参与情况下的构形在线自主辨识。以MRR系统样机为试验平台,通过多次构形辨识试验证明该方法的可行性和有效性。     

A methodology to define a reconfigurable system architecture for a compact heat exchanger assembly machine

Due to the unexpected, fast, and constant changes of market requirements and the hypercompetency, robust manufacturing systems are needed that adjust easily to operational variability and the customized product supply. The simply substitution of components, software, hardware, and/or their adaptation by parameters resetting are an attractive option to face this challenge. Short product life cycles are an undeniable consequence and evidence of this. For this reason, to develop products or services profitably in the product manufacturing field, it is common to use the product family concept, which involves sharing components, functional features, and manufacturing process, both to make a cheaper product development process and to obtain customized products. A new generation of manufacturing systems that deploy characteristics such as adaptability and flexibility responding to the market dynamics called reconfigurable manufacturing systems (RMS) are required by market according to manufacturing experts. The manufacturing systems with modular architecture are the best way to meet flexible and adaptable RMSs because they allow reconfiguration by a simple module substitution or by resetting module operation parameters. This paper presents a design methodology developed to obtain modular RMS. The method integrates the utilization of modular architecture principles, selection algorithms (analytical hierarchical process), clustering algorithms (average linkage clustering algorithm), family product features and functional system analysis in the classical product design process. The methodology proposed allows defining the most adequate modular system architecture and the modular definition of the reconfiguration variables that are needed to reach the flexibility required. A real study case about a heat exchanger assembly machine is presented where this methodology is applied in order to present an evidence of its usefulness.