Structural topology optimization with constraints on multi-fastener joint loads

This paper addresses an important problem of design constraints on fastener joint loads that are well recognized in the design of assembled aircraft structures. To avoid the failure of fastener joints, standard topology optimization is extended not only to minimize the structural compliance but also to control shear loads intensities over fasteners. It is shown that the underlying design scheme is to ameliorate the stiffness distribution over the structure in accordance with the control of load distributions over fastener joints. Typical examples are studied by means of topology optimization with joint load constraints and the standard compliance design. The effects of joint load constraints are highlighted by comparing numerical optimization results obtained by both methods. Meanwhile, resin models of optimized designs are fabricated by rapid prototyping process for loading test experiments to make sure the effectiveness of the proposed method.     

基于标定的任意半径柱面上2维条形码畸变校正

摘 要：二维条码在直接零件标识技术中应用越来越广泛,但存在标刻在柱形零件上的二维条码由于扭曲形变而无法识读的问题。为了校正这种畸变,论文分析了柱面二维条码的畸变形成原理,然后基于标定的机器视觉装置与透视投影原理建立柱面上二维条码畸变校正模型,最后通过图像信息估计出柱形零件半径参数信息,并代入畸变校正模型得到最终的校正结果。实验结果表明,该方法能够较好的校正自由半径柱面上二维条码的扭曲畸变。     

摩擦焊机液压施力系统压力特性对比分析

为分析采用电液比例计算机闭环系统进行摩擦焊接过程控制的必要性及可行性,对比分析了分别由开关阀和比例溢流阀组成的两种摩擦焊机轴向压力施力系统的静动态特性,以及长期生产过程中轴向压力波动规律,重点分析了油温对轴向压力参数的影响.结果表明,比例阀控制系统轴向压力的静、动态特性均优于开关阀系统;在长期焊接生产过程中,比例阀控制系统的轴向压力不受液压系统油温影响,比开关阀系统稳定,控制精度高,重现性好.     

数字化车间布局模糊层次评价方法研究

按照模糊层次分析法的思路建立车间布局评价的模糊层次评价模型;根据影响车间生产性能的各个因素进行分析,建立车间市局评价的指标体系;应用层次分析法确定各因素的权重;自上而下的计算各级指标关于评价目标的综合重要度;通过专家打分的方法确定方案的隶属度;根据权重、隶属度,利用模糊层次评价方法,既可对车间的布局做出综合评价.最后以某发动机关键零件牛产车间为研究对象,验证了方法的可行性和有效性.     

Optimal Packing Configuration Design with Finite-Circle Method

The Finite-circle Method (FCM) is further developed to solve 2D and 3D packing optimization problems with system compactness and moment of inertia constraints here. Instead of using the real geometrical shape as in existing solutions, we approximate the components and the design domain with circles of variant radii. Such approximation makes it possible to transform the original problem into a basic packing problem of FCM approximated components. Meanwhile, the overlapping between different components can be easily avoided by limiting the distance between corresponding circles in terms of their radii. With this formulation, the FCM provides a general and systematic approach and makes gradient-based optimization algorithms applicable. Furthermore, FCM has been extended to 3D packing problems by simply replacing circles with spheres in this paper. Several examples designing the compactness and moment of inertia of the component systems are presented to show the effect of FCM.     

Task-driven e-manufacturing resource configurable model

Manufacturing resource configuration (MRC) plays a very important role in an e-Manufacturing system. Higher requirements for optimal configuration under online resource visibility and traceability have led to two main challenges. One is that more features of manufacturing tasks affecting the optimization results should be taken into consideration when establishing the MRC mathematical model for a manufacturing cell. The other is that manufacturing information should be given equal attention as MRC to realize real-time visibility and traceability of the resulting manufacturing cells. This paper presents a comprehensive mathematical model which considers more practical features of manufacturing tasks (e.g. batch volume and alternative processing routes) for manufacturing cell formation. This model adopts a fuzzy clustering method to group the manufacturing tasks and machines. Moreover, it is enabled by a smart equipment model to realize the configurable model of real-time manufacturing information and corresponding visualization and tracing methods. A case study is given to demonstrate the proposed models and methods.     

无头铆钉自动钻铆工艺试验研究

为了提高装配质量和寿命,自动钻铆技术在飞机装配中得到广泛应用,而钻铆参数是影响装配效率和质量的关键因素。文章通过有限元模拟技术对无头铆钉铆接变形进行了分析,提炼了自动钻铆工艺参数,并结合G86自动钻铆系统,采用正交试验法进行了无头铆钉的工艺试验研究,通过极差分析法确定了无头铆钉的钻铆参数值,为无头铆钉在飞机装配中的应用提供了依据。     

基于临界约束的四轴数控加工刀轴优化方法

针对自由曲面四轴加工中复杂刀具运动导致的干涉和刀具运动不连续等现象,提出一种基于临界约束的刀轴优化方法。基于刀具与工件约束曲面之间的相对位置关系,利用曲线上的点搜索算法确定切触点处的临界刀轴矢量,并计算当前切触点刀轴摆动的可行域;以切削行内所有切触点的刀轴可行域为基础,建立当前切削行内无干涉且相邻刀轴变化最小的刀轴矢量优化模型,实现了自由曲面四轴加工无干涉刀轴矢量的光顺控制。整体叶盘四轴加工试验表明,利用此方法获得的刀轴矢量可以显著改善机床运动的连续性,并避免刀具干涉的产生,提高了加工质量。     

SDMSim: A manufacturing service supply–demand matching simulator under cloud environment

Nowadays, with the introduction and application of new information technologies in manufacturing, various advanced manufacturing modes and national strategies have been put forward and paid more and more attention, such as Industry 4.0, Industrial Internet, Cyber-Physical System or Cyber Manufacturing, Made in China 2025, Internet Plus Manufacturing, Cloud Manufacturing, etc. For these modes and strategies, how to realize the effective and intelligent supply–demand matching (SDM) of various manufacturing resources and capabilities (MR&C) in the form of service is one of the common issues and aims. In order to provide a uniformed research platform for related researchers both in academic and industry, the concept of manufacturing service SDM simulator (SDMSim) is proposed in this paper. A hypernetwork based architecture for the simulator is designed, as well as its seven key functions and subsystems, including manufacturing service management, manufacturing task management, manufacturing service SDM hypernetwork, manufacturing service SDM problem formulation and configuration, matching and scheduling algorithms/strategies selection and design, statistical analysis, and visualization. It illustrates that SDMSim has the potential to serve the users of manufacturing service provider, manufacturing service consumer, manufacturing service operator in the field of SoM, as well as the related researchers.     

Scheduling jobs with ready times and precedence constraints on parallel batch machines using metaheuristics

In this paper, we discuss a scheduling problem for parallel batch machines where the jobs have ready times. Problems of this type can be found in semiconductor wafer fabrication facilities (wafer fabs). In addition, we consider precedence constraints among the jobs. Such constraints arise, for example, in scheduling subproblems of the shifting bottleneck heuristic when complex job shop scheduling problems are tackled. We use the total weighted tardiness as the performance measure to be optimized. Hence, the problem is NP-hard and we have to rely on heuristic solution approaches. We consider a variable neighborhood search (VNS) scheme and a greedy randomized adaptive search procedure (GRASP) to compute efficient solutions. We assess the performance of the two metaheuristics based on a large set of randomly generated problem instances and based on instances from the literature. The obtained computational results demonstrate that VNS is a very fast heuristic that quickly leads to high-quality solutions, whereas the GRASP is slightly outperformed by the VNS approach. However, the GRASP approach has the advantage that it can be parallelized in a more natural manner compared to VNS.