A framework of virtual prototyping environment for the design and analysis of mechanical mechanism with clearance

Mechanical mechanisms with clearance abound in technological fields such as robotics, machine and steam turbine industry. The dynamic performance of these mechanisms in working condition can be achieved provided that the effects of the different on the mechanisms (such as mechanism dynamics, technological effects and thermal behaviour) are thoroughly understood. Virtual prototyping provides an integration of multi-domain dynamic simulation for the design and analysis process. In the current paper, a framework of virtual prototyping environment for the design and analysis of mechanical mechanism with clearance is presented. A case study with such a simulation strategy is studied for the optimum design and analysis of the technological parameter.     

Multidisciplinary design process based on virtual prototyping for microsystem design

Microsystem design involves the mixing of two main disciplines: mechanical engineering and electronics. Multidisciplinary design approach is not easy to implement and becomes more difficult when the challenge consists in simultaneously handling new knowledge that characterizes the field of microsystem industry. We present herewith a new multidisciplinary engineering approach used to lead the detailed design of micro-accelerometers based on virtual tools. Virtual prototyping that is usually implemented in one sole domain of competence is developed to be manipulated by either experts from electronics or mechanics. This new tool improves collaboration and the rapid identification of highly satisfying solutions. The virtual tool allows exploration of micromechanical devices and system design issues and objectives. It uses interactions with the designer in order to achieve solutions integrating the physics rules of the design and the experience of the designer.     

基于虚拟样机和粒子系统仿真技术的虚拟布线方法

将虚拟样机技术应用于机电产品电缆布线问题,提出了虚拟布线方法。该方法首先根据设计方案建立产品虚拟样机、电缆连接列表、电缆接口、电缆材料、截面参数等信息,基于上述信息以及电缆布线规范,利用虚拟样机技术对可视化和人机交互能力的支持规划出卡箍位置和电缆路径,进而计算电缆长度,在此基础上利用粒子系统仿真技术计算电缆形状,据此生成相应的电缆模型。在探讨了机电产品电缆布线问题及其求解思路的基础上,着重研究了机电产品的信息模型及虚拟布线的关键技术。通过一个实例证明了该方法的可行性。     

基于虚拟样机技术的汽车操纵稳定性参数正交优化设计

以某型轿车底盘为研究对象,采用虚拟样机软件ADAMS建立整车多体动力学仿真模型;结合汽车操纵稳定性的客观定量评价标准,建立了直接生成操纵稳定性评价值的ADAMS函数;用ADAMS软件结合正交试验方法对整车操纵稳定性进行了虚拟正交优化设计.虚拟样机技术在车辆操纵稳定性参数正交优化中的应用,不仅使仿真模型与集中质量模型相比提高了精度,还分析出整车操纵稳定性的主要零部件影响因素,得到了最优的一组设计方案.由于是直接对具体零部件的优化,整个设计过程适于在企业中应用.     

Design of high performance badminton shuttlecocks: virtual and rapid prototyping approach

In this paper, a framework utilising virtual and rapid prototyping to aid design of a shuttlecock skirt was proposed and implemented. A standard template for flow simulation on ANSYS® CFX was developed to predict the aerodynamic performance of the virtual prototypes, with focus on reduced simulation time and complexity. This forms the basis of the computer aided design model – computational fluid dynamics – performance evaluation loop in the proposed framework. Steady state flow simulation was conducted for three simple computer aided design models of shuttlecocks, with different gap dimensions on the skirt. Wind tunnel drag study of the models reproduced through rapid prototyping validated the simulation result. The proposed methodology can also be applied to the existing design process for integration of virtual and rapid prototyping to reduce the burden of design iteration.     

The virtual biomodel as a complementary resource for the diagnosis of mandibular ankylosis

Ankylosis of the mandibular joint is one of many pathologies that affect the temporomanbibular joint. It comprises the mandible condyle, the base of the skull bone and the joint itself, inducing changes in the skull bone and face complex, affecting their growth to different degrees, which can cause morphofunctional alterations. The objective of this paper is to show the gains of using a virtual biomodel as an additional resource in the diagnosis of mandibular joint ankylosis, besides the analysis of multiplanar slices.     

Analysis of the bullet nose of an aero-engine for bird impact through virtual and rapid prototyping

Flying was inspired by birds. But ironically bird strikes are a menace. Therefore, aero-engines have to be designed to survive these strikes. The design of the bullet nose of an aero-engine during a bird strike is presented in this paper. A Finite Element Analysis (FEA) model was developed for this purpose. It was then fine-tuned through experiments on bullet noses built using Laser-Engineered Net-Shaping (LENS). Through this approach, several design alternatives could be evaluated virtually and only a few physical experiments were required for validation. The outcome is not only a rapid and safe bullet nose design but also a realistic FEA model.     

含关节间隙的3-CPaRR解耦并联机构弹性动力学建模与分析

为研究关节间隙对柔性化条件下并联机构输出运动特性的影响,以3-CPaRR并联机构为研究对象。首先,根据该并联机构的空间位置关系,研究了该并联机构的运动学规律,表明该并联机构驱动圆柱副可等效分解为驱动移动副和被动转动副;其次,基于空间位置矢量模型,建立了含间隙转动关节径向和轴向的运动学模型,从而进一步建立各支链转动关节处含间隙的运动学模型;然后,基于Lankarani-Nikravesh接触力模型和Coulomb摩擦力模型建立各支链转动副处存在关节间隙时的法向、切向力学模型,并将各被动关节处由于间隙的存在而产生的力向驱动关节处进行转化,从而建立了含关节间隙的3-CPaRR并联机构弹性动力学模型,最后通过实例分析了不同的关节间隙对该并联机构运动特性的影响。结果表明:含有关节间隙的柔性支链对并联机构的输出运动特性产生了重要的影响,同时该研究也为其他的含关节间隙的多体系统弹性动力学建模提供了理论基础。     

A multi-agent virtual enterprise model and its simulation with Swarm

Virtual enterprise (VE) is a considerably complex organization in the world. More efforts have been made to establish such organization, among which multi-agent modelling and simulation are regarded as a promising approach. In this paper, MAS theory and technology are briefly reviewed. A novel multi-agent VE model is provided with a comparison with related work. Swarm as an outstanding multi-agent simulation programming tool is introduced. A modelling and simulation platform is developed with Swarm. The framework and main components of the platform are illustrated. The procedure of modelling VE on this platform is proposed. A case study using the platform on VE establishment in manufacturing domain is presented, and several common formulae to measure the performance of manufactures are developed in this case study.     

计及运动副间隙的双曲柄六杆压力机机构动力学仿真向量键合图法

针对计及运动副间隙的双曲柄六杆压力机机构动力学仿真问题,提出了相应的向量键合图法.基于修正非线性连续接触碰撞力的混合模型,推导出间隙运动副的相对碰撞速度向量方程.在此基础上,建立了可以更精确描述间隙运动副的向量键合图模型,具有通用性强、模块化的特点,便于嵌入到系统的向量键合图模型中.由机构运动副的约束关系,将各构件的向...     

基于GTN损伤模型的压力连接过程仿真

为了准确地反映压力连接过程中材料的破坏,在仿真模型中引入了GTN损伤模型.研究了损伤模型中影响孔洞形核、成长及聚合的材料参数,模拟了压力连接过程中材料的破坏行为,并分析了连接过程材料最先断裂的位置.结果表明,GTN损伤模型可以较好地反映上板件颈部在连接过程中的断裂,并较好地判断出了连接点断裂的初始位置在上板件颈部处的内侧,更加准确地模拟了连接过程中材料的破坏过程.     

不同工况下含间隙铰链接触碰撞力特性研究

为了更加准确地研究不同工况环境对含间隙铰链接触碰撞力的影响,以提高空间机构的运行及空间指向精度,基于分型理论、Lankarani-Nikravesh模型及宏微观理论,考虑摩擦与微凸体间的阻尼等因素,得到了新的含间隙旋转运动副元素间接触碰撞力模型,并通过试验验证了该模型的正确性.采用单一因素试验法,研究了转速、间隙、不同...     

含2个S副间隙6-SPS机构奇异性分析

6-SPS机构位姿矩阵采用四元数法描述,并将该矩阵和矢量坐标扩展为4维形式,推导出无间隙机构的运动方程,得到了机构运动的新型雅克比矩阵J_A和J_B;在此基础上,利用连续接触模型得到了两个含间隙S副共连杆和异杆时机构的运动系数矩阵。分别把各个运动系数的行列式展开,得到含间隙机构第一类奇异和第二类奇异的轨迹方程,利用MATLAB得到了机构在给定位置时的第一类位姿奇异轨迹和第二类位姿奇异三维轨迹曲面;通过将两类含间隙机构奇异轨迹曲面的比较,发现机构间隙对第二类奇异的影响大于对第一类奇异的影响;在两类奇异轨迹中,当S副异杆时,机构间隙的影响均大于S副共连杆时的影响。以无间隙机构奇异轨迹曲面上奇异点作为参考点,通过含间隙机构奇异轨迹曲面上与参考点相对应奇异点的相互比较,发现存在一个关于参考点的奇异域。     

一种含间隙解耦并联机构动力学分析与混沌现象辨识

以自主提出的一种两转动解耦并联机构为研究对象,阐述机构结构组成,并针对其运动副存在间隙状况,建立含间隙机构动力学模型;基于ADAMS软件进行动力学仿真,并分析在有无运动副间隙、不同间隙和驱动速度下,机构位移、速度、加速度以及运动副接触力的变化;借助Poincare截面映射法对解耦并联机构动力学行为中的混沌现象予以辨识,绘制Poincare映射图,揭示间隙对机构动力学特性的影响。研究结果表明含间隙解耦并联机构存在混沌运动现象,对其更进一步的非线性动力学研究有一定指导意义。     

冗余驱动地震模拟台虚拟样机动力学分析

1.College of Engineering, Shantou University, Shantou 515063, China;
2.Shantou Institute for Light Industrial Equipment Research, Shantou 515021, China;
3.State Key Laboratory of Mechanical System and Vibration, Shanghai Jiaotong University, Shanghai 200240, China     

Finite element analysis of postbuckling and delamination of composite laminates using virtual crack closure technique

The two-dimensional and three-dimensional parametric finite element analysis (FEA) of composite flat laminates with two through-the-width delamination types: 0₄/(±θ)₆//0₄ and 0₄//(±θ)₆//0₄ (θ = 0°, 45°, and “//” denotes the delaminated interface) under compressive load are performed to explore the effects of multiple delaminations on the postbuckling properties. The virtual crack closure technique which is employed to calculate the energy release rate (ERR) for crack propagation is used to deal with the delamination growth. Three typical failure criteria: B-K law, Reeder law and Power law are comparatively studied for predicting the crack propagation. Effects of different mesh sizes and pre-existing crack length on the delamination growth and postbuckling properties of composite laminates are discussed. Interaction between the delamination growth mechanisms for multiple cracks for 0₄//(±θ)₆//0₄ composite laminates is also investigated. Numerical results using FEA are also compared with those by existing models and experiments.     

Rapid prototyping and flow simulation applications in design of agricultural irrigation equipment: Case study for a sample in-line drip emitter

In this study, a 3D CAD solid model of a sample agricultural irrigation emitter was created and the flow behaviour was simulated in its labyrinth channels by using a flow simulation technique. Referenced by the original design, the channel geometry was modified and the emitter was re-fabricated using rapid prototyping/additive manufacturing techniques. The flow behaviour is then re-investigated based on the re-shaped channel geometry of the labyrinth structure. The predetermined optimum pressure in the pipe was validated experimentally for both the original design and modified designs. As a result, the optimum pressure in the pipe and the flow characteristics for original both the design and modified designs of the emitter were validated. This study contributes to further research into the development of agricultural irrigation equipment aided through the utilisation of additive manufacturing and computer aided engineering tools.     

虚拟人的步行和跑步运动控制方法的研究

研究了虚拟人的步行和跑步两种基本运动模型及其运动控制方法。首先提出了人体的几何模型和运动学模型,其次对人体行走和跑步模型进行分析后,提出了用关键帧,正向、逆向运动学和简单动力学适当结合的控制方法,实现了周期的步行、跑步等移动动作,并引入运动特征参量来控制步行和跑步速度、频率及步幅特征。     

The role of Bill of Materials and Movements (BOMM) in the virtual enterprises environment

Organizing and managing dynamic networks of enterprises (or virtual enterprises (VE)) is a very complex task and many issues are still to be effectively covered. Apart from the models that can be used to create and manage VEs, product data play a central role in the VE life cycle. VE composition, interaction among VE members (Autonomous Production Systems in this work), as well as its relationship with the market, is severely dependent on the product technical specifications as well as on the product process planning information. In traditional managing systems for the single enterprise environment the Bill of Materials (BOM) plays that role and in this paper is proposed a Bill of Materials and Movements (BOMM) as its equivalent in VE environments. The BOMM includes product structure, high level process planning information and some degree of VE composition. BOMM is present during VE formation, operation, and reconfiguration, playing a central role in the material detailed planning and in the movement planning between VE members. In this article the BOMM role during the VE life cycle is described in detail.