基于TRIZ进化理论的产品造型设计方法探讨

通过对TRIZ进化理论的介绍,结合产品造型设计学的相关知识,探索出关于产品造型进化模式与进化路线,为设计者提供了一个有效的启发式的造型设计方法。     

用快速成形技术开发新产品

随着社会的不断进步和科学技术的快速发展,人们对产品的要求已不再只停留在可用的基础上,而是逐渐进入了个性化的消费阶段,既要好用,同时产品的外观造型颜色等又要符合其个人的审美情趣,这就要求企业的设计者不但能根据市场的要求很快地设计新产品,而且要在尽可能短的时间内制造出产品的样品,并进行相应的产品评估,性能测试,同时征求客户的意见,进行修改,从而完成产品的最终定型。而这一过程的关键就在于如何尽可能快的制造出样品以验证设计者的设计方案。用传统方法制作样品时,往往取决于加工者的技术水平,同时需使用多种机械加     

混流制造车间物料配送路径优化

物料及时、准确送到混流制造系统的各工位节点不仅是系统正常运行的保证,也是混流系统高效运转的根本。针对混流制造系统物料配送车辆路径优化问题,从优化目标、约束条件和影响因素等方面考虑,建立了以车辆行驶距离最短、车辆利用率最大和配送次数最少为优化目标的多目标配送车辆路径优化模型。根据问题的具体情况,设计了解决该多目标优化问题的双层递进进化多目标优化算法,给出了算法的进化过程和交叉、变异模式及其实现过程。通过一个混流装配系统的实例证明了所建立的模型和设计算法的有效性。     

基于遗传算法的产品人机CAD研究

将产品形态的人机设计问题从概念设计到详细设计分为交互模式设计、关联形态设计和独立形态设计3个紧密联系的层。应用进化设计和遗传算法的基本原理,针对不同层次人机设计问题的特点分别进行具体研究,制订了相应的解决策略,分析了其编码方案与适应度函数的构造方式。最后构建了基于设计/制造一体化的人机进化设计过程原型系统。     

一种基于ACIS平台的创新进化设计方法

随着智能计算机辅助设计技术的发展,进化设计方法已经成为最重要的创新设计技术之一.众多的造型平台又为CAD系统的开发提供强大的支持.将遗传算法应用于创新设计时,容易受到造型工具和设计者自身创新能力的限制.文中提出一种将遗传算法和特定的造型技术相结合的创新设计方法.该方法充分利用遗传算法的进化功能和ACIS平台强大的造型优势,通过进化产生更具创意的产品造型,为设计者的创新设计提供更强大的支持.实验表明,该方法在创新进化系统中有很好的应用前景.     

模拟跨导滤波器多目标并行进化的设计

以往模拟滤波器的设计,需要经过人工多次修改、计算和调试。提出一种模拟跨导滤波器的硬件进化结构及多目标并行进化的设计方法。应用一种基于渗透原理迁移策略的多目标并行遗传算法,实现跨导滤波器的参数优化。对多目标并行遗传算法的遗传操作进行了改进,构造了适合滤波器参数进化的多目标适应度函数。在高[Q]值的跨导滤波器的设计中,采用级联法构成的四阶带通跨导滤波器能够满足其在阻带、通带以及过渡带方面的性能要求,对其实效性进行了仿真和验证,进化的参数数值与理论结果符合得非常好。     

面向加工环境的公差设计研究与开发

作为分析手段的公差设计是连接产品性能要求和加工工艺之间的桥梁，它不仅影响产品的性能，也影响到产品的生产成本和加工工艺过程。如何合理地分配公差和控制累积误差是涉及产品性价比的关键，当然也就是决定产品竞争胜负的关键。计算机辅助公差设计作为并行设计环境中的一个重要决策工具，其目标是在保证功能和性能的前提下使制造成本最低。其重要性是不言而喻的，但对它的研究却不够，始终是ＣＡＸ中的薄弱环节，有许多问题急待解决。一、传统公差设计系统与并行公差设计系统比较传统公差设计系统的最大不足是缺少面向制造性，对它的研究…     

微机平台上CAD/CAE/CAM/PDM系统集成方案探讨(之二)──企业是否需要CAE及COSMOS软件

一、现代化的企业离不开CAE现在，企业面临的最大挑战是怎样快速地推出可以信赖的高品质产品。达到这一目标的途径只有缩短产品的设计周期，降低产品的制造成本。问题是如何去缩短，怎样来降低呢？在一个现代化的企业中，CAD／CAM已经减少了不少设计者的负担，原来被视为CAD／CAM中配角的CAE（计算机辅助工程）已经不再是以前的可有可无了，现在已经是高品质设计中不可缺少的重要一环，CAE不仅可以减少CAM中制造实体模型的次数，还可以帮助设计者在CAD中合理建构几何实体模型。因此合理运用CAE可以缩短产品的开发时间，减少产品…     

基于多种群差分进化的多目标优化算法

针对差分进化算法(Differential Evolution Algorithm,DE)求解多目标优化问题时易陷入局部最优的问题,设计了一种双向搜索机制,它通过对相反进化方向产生的两个子代个体进行评价,来增强DE算法的局部搜索能力;设计了多种群机制,它可令各子群独立进化一定次数再执行全局进化,以完成子群间进化信息的交流,这一方面降低了算法陷入局部最优的风险,另一方面增强了Pareto解集的多样性,使Pareto前沿面的解集分布更为均匀。实验结果表明,相比于NSGA-II等同类算法,所提方法在搜索Pareto最优解时效率更高,并且Pareto最优解集的精度及分布程度比前者更好。     

CAMWorks在产品加工中的应用

随着世界制造中心向中国转移,中国制造业近几年来得到迅速发展,但竞争也更加激烈,依赖信息化技术快速响应市场并持续创新产品,已成为企业提升竞争力赢得优势的关键.CAD/CAM技术的应用可提高企业产品开发能力、缩短产品研制周期、降低开发成本、实现最佳设计目标和企业间的协作,使企业能在最短时间内组织全球范围的设计和制造资源开发出新产品.因此,越来越多的制造企业对CAD/CAM的需求不断升级.     

The status,challenges, and future of additive manufacturing in engineering

Additive manufacturing (AM) is poised to bring about a revolution in the way products are designed, manufactured, and distributed to end users. This technology has gained significant academic as well as industry interest due to its ability to create complex geometries with customizable material properties. AM has also inspired the development of the maker movement by democratizing design and manufacturing. Due to the rapid proliferation of a wide variety of technologies associated with AM, there is a lack of a comprehensive set of design principles, manufacturing guidelines, and standardization of best practices. These challenges are compounded by the fact that advancements in multiple technologies (for example materials processing, topology optimization) generate a “positive feedback loop” effect in advancing AM. In order to advance research interest and investment in AM technologies, some fundamental questions and trends about the dependencies existing in these avenues need highlighting. The goal of our review paper is to organize this body of knowledge surrounding AM, and present current barriers, findings, and future trends significantly to the researchers. We also discuss fundamental attributes of AM processes, evolution of the AM industry, and the affordances enabled by the emergence of AM in a variety of areas such as geometry processing, material design, and education. We conclude our paper by pointing out future directions such as the “print-it-all” paradigm, that have the potential to re-imagine current research and spawn completely new avenues for exploration.     

An ontology-oriented knowledge methodology for process planning in additive layer manufacturing

The goal of this research is the generation of a novel knowledge with process-oriented ontology and the informal model. With regard to the proposed ontology, it establishes an improvement to related ontologies because it involves the demands of fabrication engineering and, specifically, the layer-upon-layer manufacturing planning process with various AM systems. Generally, task of AM planning indicates to make repeated and essential decisions which are always on the basis of the engineers’ knowledge and experience in additive manufacturing. Hence, it is a suitable field towards the execution of a knowledge-based engineering system. To represent the knowledge at an upper tier, the IDEF0 diagrams is introduced for identifying the sequence of tasks contained in the AM planning. They are a vital resources for defining the sequence of tasks and the messages flow. Afterward, these messages are analyzed thoroughly by applying schematic graphs, and then they are categorized into knowledge segments. Eventually, each knowledge segment is further divided into knowledge entities. At the same time, the relationships among them are also defined.Meanwhile, knowledge modeling involved generating an ontology of design feature which is utilized as a general information model in both computer-aided design and process planning, expression of fabrication criteria that depict the basis and properties for picking fabrication parameters. In a first method, the ontology has been examined utilizing an essential activity in AM planning: the task related to the confirmation of parameters over component quality. In this task, decisions have to be made in the orientation, slicing and the other process parameters. In this research, the differences between geometric and dimensional tolerance fabrication is considered in the generated methodology. The knowledge needed to aid all decisions is expressed utilizing the proposed ontology.     

Hierarchical contour matching for dental X-ray radiographs

The goal of forensic dentistry is to identify individuals based on their dental characteristics. In this paper we present a new algorithm for human identification from dental X-ray images. The algorithm is based on matching teeth contours using hierarchical chamfer distance. The algorithm applies a hierarchical contour matching algorithm using multi-resolution representation of the teeth. Given a dental record, usually a postmortem (PM) radiograph, first, the radiograph is segmented and a multi-resolution representation is created for each PM tooth. Each tooth is matched with the archived antemortem (AM) teeth, which have the same tooth number, in the database using the hierarchical algorithm starting from the lowest resolution level. At each resolution level, the AM teeth are arranged in an ascending order according to a matching distance and 50% of the AM teeth with the largest distances are discarded and the remaining AM teeth are marked as possible candidates and the matching process proceeds to the following (higher) resolution level. After matching all the teeth in the PM image, voting is used to obtain a list of best matches for the PM query image based upon the matching results of the individual teeth. Analysis of the time complexity of the proposed algorithm prove that the hierarchical matching significantly reduces the search space and consequently the retrieval time is reduced. The experimental results on a database of 187 AM images show that the algorithm is robust for identifying individuals based on their dental radiographs.     

基于CORDIC算法的AM解调技术研究

提出了一种基于CORDIC算法的数字正交AM解调设计技术,讨论了AM解调的原理,重点分析了利用CORDIC算法综合实现数控振荡器与混频器、计算开平方的过程,介绍了关键模块的设计方案,仿真结果表明:该方法高精度地完成了AM解调,具有较高的工程应用价值。     

Additively manufactured respirators: quantifying particle transmission and identifying system-level challenges for improving filtration efficiency

The COVID-19 pandemic has disrupted the supply chain for personal protective equipment (PPE) for medical professionals, including N95-type respiratory protective masks. To address this shortage, many have looked to the agility and accessibility of additive manufacturing (AM) systems to provide a democratized, decentralized solution to producing respirators with equivalent protection for last-resort measures. However, there are concerns about the viability and safety in deploying this localized download, print, and wear strategy due to a lack of commensurate quality assurance processes. Many open-source respirator designs for AM indicate that they do not provide N95-equivalent protection (filtering 95% of SARS-CoV-2 particles) because they have either not passed aerosol generation tests or not been tested. Few studies have quantified particle transmission through respirator designs outside of the filter medium. This is concerning because several polymer-based AM processes produce porous parts, and inherent process variation between printers and materials also threaten the integrity of tolerances and seals within the printed respirator assembly. No study has isolated these failure mechanisms specifically for respirators. The goal of this paper is to measure particle transmission through printed respirators of different designs, materials, and AM processes. The authors compare the performance of printed respirators to N95 respirators and cloth masks. Respirators in this study printed using desktop- and industrial-scale fused filament fabrication processes and industrial-scale powder bed fusion processes were not sufficiently reliable for widespread distribution and local production of N95-type respiratory protection. Even while assuming a perfect seal between the respirator and the user’s face, although a few respirators provided >90% efficiency at the 100−300 nm particle range, almost all printed respirators provided <60% filtration efficiency. Post-processing procedures including cleaning, sealing surfaces, and reinforcing the filter cap seal generally improved performance, but the printed respirators showed similar performance to various cloth masks. The authors further explore the process-driven aspects leading to low filtration efficiency. Although the design/printer/material combination dictates the AM respirator performance, the identified failure modes originate from system-level constraints and are therefore generalizable across multiple AM processes. Quantifying the limitations of AM in producing N95-type respiratory protective masks advances understanding of AM systems toward the development of better part and machine designs to meet the needs of reliable, functional, end-use parts.     

基于FPGA的AM发射机设计

本课题研究的是一个基于FPGA设计的AM发射机的制作过程,通过用Verilog语言来设计一个简单的AM发射机。根据实际情况,本系统主要是从系统的最底层的模块的描述,通过对AM发射机的制作,熟悉FPGA硬件编程。本文介绍了此软件系统的具体设计思路和设计原理,并对设计过程中所遇到的各种问题,进行了分析并对相应问题提供了具体的解决方案。     

基于FPGA的AM发射机设计

本课题研究的是一个基于FPGA设计的AM发射机的制作过程,通过用Verilog语言来设计一个简单的AM发射机。根据实际情况,本系统主要是从系统的最底层的模块的描述,通过对AM发射机的制作,熟悉FPGA硬件编程。本文介绍了此软件系统的具体设计思路和设计原理,并对设计过程中所遇到的各种问题,进行了分析并对相应问题提供了具体的解决方案。     

基于DDS技术的数字调幅的设计与实现

调幅是无线电通讯中的一种常用方法。对比于模拟调幅,数字调幅具有精度高、可控性强等优势。本文从调幅的理论出发,分析了数字调幅实现中的关键问题以及各参数指标的实现方法,并使用matlab工具作了仿真,仿真结果满足设计要求。最后,本文给出了一种基于DDS技术的数字调幅的实现方法以及试验结果,结果表明,所设计的数字调幅方法正确,波形稳定,有一定的实用价值。     

Additive manufacturing in the spare parts supply chain

As additive manufacturing (AM) evolves to become a common method of producing final parts, further study of this computer integrated technology is necessary. The purpose of this research is to evaluate the potential impact of additive manufacturing improvements on the configuration of spare parts supply chains. This goal has been accomplished through scenario modeling of a real-life spare parts supply chain in the aeronautics industry. The spare parts supply chain of the F-18 Super Hornet fighter jet was selected as the case study because the air-cooling ducts of the environmental control system are produced using AM technology. In total, four scenarios are investigated that vary the supply chain configurations and additive manufacturing machine specifications. The reference scenario is based on the spare parts supplier's current practice and the possible future decentralization of production and likely improvements in AM technology. Total operating cost, including downtime cost, is used to compare the scenarios. We found that using current AM technology, centralized production is clearly the preferable supply chain configuration in the case example. However, distributed spare parts production becomes practical as AM machines become less capital intensive, more autonomous and offer shorter production cycles. This investigation provides guidance for the development of additive manufacturing machines and their possible deployment in spare parts supply chains. This study contributes to the emerging literature on AM deployment in supply chains with a real-world case setting and scenario model illustrating the cost trade-offs and critical requirements for technology development.     

An additive manufacturing filter for topology optimization of print-ready designs

Additive manufacturing (AM) offers exciting opportunities to manufacture parts of unprecedented complexity. Topology optimization is essential to fully exploit this capability. However, AM processes have specific limitations as well. When these are not considered during design optimization, modifications are generally needed in post-processing, which add costs and reduce the optimized performance. This paper presents a filter that incorporates the main characteristics of a generic AM process, and that can easily be included in conventional density-based topology optimization procedures. Use of this filter ensures that optimized designs comply with typical geometrical AM restrictions. Its performance is illustrated on compliance minimization problems, and a 2D Matlab implementation is provided.