基于搅拌摩擦的金属固相增材制造研究进展EI北大核心CSCD

基于搅拌摩擦的固相增材制造是大型轻质合金构件成形制造的新技术,已成为国内外先进成形制造领域研究的热点之一。本文对目前国内外基于搅拌摩擦的金属固相增材制造技术及其相关工艺机理的研究现状进行了分析和总结。常见的基于搅拌摩擦的固相增材制造技术可分为三类:基于搅拌摩擦搭接焊原理,使板材逐层堆积,从而获得增材构件的搅拌摩擦增材制造(friction stir additive manufacturing,FSAM)技术;采用中空搅拌头,通过添加剂(粉末或丝材)进行固相搅拌摩擦沉积的增材制造(additive friction stir deposition,AFSD)技术;采用消耗型棒材,通过棒材的摩擦表面处理,形成增材层的摩擦表面沉积增材制造(friction surfacing deposition additive manufacturing,FSD-AM)技术。重点分析了金属材料基于搅拌摩擦的固相增材制造技术的国内外研究与应用现状,对比了三类基于搅拌摩擦的固相增材制造技术的特征及其工艺优缺点。最后指出增材工艺机理、形性协同控制、外场辅助工艺改型、新材料应用和人工智能优化是基于搅拌摩擦的固相增材制造技术未来研究的重点方向。     

钢的激光增材制造研究进展及前景展望

激光增材制造是一种兼顾精确成形和高性能需求的一体化制造技术,为钢构件的高质量快速制造提供了新思路、新方法。从目前典型钢构件的激光增材制造成形质量控制、组织特征、力学性能和应用现状4个方面出发,主要综述了不同的能量输入及氧含量对成形致密度的影响,提出了如何降低孔隙率的方法,对比了不同激光增材制造工艺方法下,制备模具钢、不锈钢和超高强钢试件热处理前后的微观组织和力学性能。在此基础上,对钢构件激光增材制造的发展趋势和需要进一步深入研究的问题进行了讨论,指出了激光增材制造修复技术与超声辅助工艺相结合的发展前景。     

金属多材料增材制造研究现状与展望

当代社会对产品的功能及性能的要求越来越高,苛刻的使役条件要求零件具有功能耦合、多环境适应的能力。金属多材料增材制造技术相比传统制造技术具备更大的优势,在航空航天、汽车工业、电力行业、生物医学等领域中均具有广阔的应用前景。研究了电子束增材制造、电弧增材制造和冷喷涂增材制造在金属多材料增材制造中的应用现状以及最新发展。重点研究了金属多材料增材制造技术在宏观成形精度、微观组织缺陷和粒子界面结合中存在的关键问题。最后,指出了金属多材料增材制造技术在材料种类、基础理论、零件复杂度、质量控制等方面的发展趋势。将为金属多材料应用于增材制造技术提供新的思路和借鉴价值。     

Topologically engineered 3D printed architectures with superior mechanical strength

Materials that are lightweight yet exhibit superior mechanical properties are of compelling importance for several technological applications that range from aircrafts to household appliances. Lightweight materials allow energy saving and reduce the amount of resources required for manufacturing. Researchers have expended significant efforts in the quest for such materials, which require new concepts in both tailoring material microstructure as well as structural design. Architectured materials, which take advantage of new engineering paradigms, have recently emerged as an exciting avenue to create bespoke combinations of desired macroscopic material responses. In some instances, rather unique structures have emerged from advanced geometrical concepts (e.g. gyroids, menger cubes, or origami/kirigami-based structures), while in others innovation has emerged from mimicking nature in bio-inspired materials (e.g. honeycomb structures, nacre, fish scales etc.). Beyond design, additive manufacturing has enabled the facile fabrication of complex geometrical and bio-inspired architectures, using computer aided design models. The combination of simulations and experiments on these structures has led to an enhancement of mechanical properties, including strength, stiffness and toughness. In this review, we provide a perspective on topologically engineered architectured materials that exhibit optimal mechanical behaviour and can be readily printed using additive manufacturing.     

核电用316L不锈钢粉末增材制造研究现状

增材制造技术是一种无须模具、近净成形的先进制造工艺。不锈钢是一种在核电行业广泛应用的结构材料。实现不锈钢结构件的增材制造将进一步推动增材制造技术的发展,也可为核行业带来革命性改变。以核电用316L不锈钢为例,系统阐述了不锈钢粉末增材制造研究现状,包括粉末制备工艺现状、增材制造成形工艺现状以及成形件的组织性能研究现状。目前,增材制造用316L不锈钢粉末的制备工艺主要为雾化法,粉末的物化性能受制粉工艺参数的影响。在激光粉末床熔融增材制造技术、电子束选区熔化技术和等离子增材制造技术中,尤以激光粉末床熔融增材制造不锈钢的应用最为广泛。增材制造316L不锈钢的组织与性能存在各向异性,但各向异性可通过增材制造的后处理技术消除。目前增材制造最为常用的后处理技术为热处理。与锻造316L不锈钢相比,经热等静压处理的增材制造316L不锈钢的力学性能与辐照性能更优。目前,核用不锈钢的增材制造技术还处于起始阶段,后续应重点关注增材制造的成形机理及成形材料中子辐照性能等内容。     

Design knowledge representation to support personalised additive manufacturing

ABSTRACT

This research aims to develop a set of new formal design representations that captures design requirements to improve the level of personalisation while taking advantage of the additive manufacturing (AM)-enabled design freedom. We propose a formal design process structure called design for AM-facilitated personalisation that merges design for personalisation and design for additive manufacturing. Also, we propose formal representations for an artefact–user interaction using finite state automata and goal-oriented user behaviours in the artefact use as formal language sets based on discrete event systems. By adopting the relational properties of affordance, effectivity, and preference, the proposed formal representations systemically link user behaviour-related artefact properties and user preferences to the design requirements for additive manufactured artefacts. This paper presents a case study of personalised chair design and a simulation of user behaviours in the chair–user interaction.     

搅拌摩擦沉积增材技术研究进展EI北大核心

搅拌摩擦沉积增材(additive friction stir deposition,AFSD)技术是一种新兴固相增材制造技术,采用金属棒材、粉材、丝材为增材材料,增材过程中依靠增材材料与板材摩擦产生摩擦热以及材料剧烈变形产生的塑性变形热形成黏塑性沉积层,沉积层逐层堆积形成三维实体结构件;基于其固相特征,具有熔覆增材技术不可比拟的优势,目前已成为增材制造领域的研究热点。本文从设备研制、微观组织演变、材料流动特性、力学性能变化四个方面综述了AFSD技术最新国内外研究进展;分析了该技术应用于工程实际的可行性,展望了在增材制造、材料修复、零件加固、制造金属涂层领域的应用前景;最后指出了产热机制、材料流动特性、辅助优化工艺、智能化设备研制等为未来的研究方向。     

How will the diffusion of additive manufacturing impact the raw material supply chain process?

This study investigates the potential of additive manufacturing (i.e. 3D printing) to alter established manufacturing and supply chain processes, complementing previous research work that deals with additive manufacturing and rapid prototyping. Additive manufacturing is a manufacturing technique, which allows the direct fabrication of three-dimensional design models using an additive approach by adding layer after layer. As additive manufacturing is inherently less wasteful and only applies raw material where needed, it constitutes a chance to reduce materials usage and related inventories. Even though the technology has faced considerable hype, its adoption still does not match the high expectations. The aim of this study is to overcome limitations of state-of-the-art impact assessments by integrating the potential reduction of materials inventories through the adoption of additive manufacturing in manufacturing and to point out possible implications for supply chain processes. For this purpose, a dynamic evaluation model was developed analysing the adoption of additive manufacturing by integrating the Bass Diffusion Model to provide interesting and novel results for both practitioners and researchers. The study shows that additive manufacturing can indeed reduce raw materials inventory by approximately 4% and that the diffusion rate is likely to be affected by the utility of the technology.     

增材制造铜/钢双金属材料研究进展

铜/钢双金属材料具有力学强度高、物理化学性能优良等优势,在交通运输、电力能源和建筑工业等领域应用前景广阔。然而,传统熔铸工艺在制造铜/钢双金属材料时,容易在铜/钢界面处产生偏析现象,在一定程度上限制了铜/钢双金属材料的发展。与传统工艺相比,增材制造技术不仅能实现复杂加工零件的快速制造,而且在成形过程中较短的保温时间能缓和或消除异种金属材料界面产生的冶金缺陷,进而增强铜/钢双金属材料的力学性能。由于双金属材料是近年来的研究热点,有关增材制造铜/钢双金属材料的综述性文章较少,故综述了近年来激光、电子束及电弧增材制造技术制造铜/钢双金属材料的研究发展现状,分析了各技术的优缺点,并从制备方法、工艺参数及界面合金元素等角度,分析了影响材料界面组织性能变化的关键因素。发现在增材制造铜/钢双金属材料方面,目前激光增材制造技术主要应用于精度要求较高的小尺寸零部件,电子束增材制造技术适用于某些具有特殊性能的合金,如钛合金,而电弧增材制造技术适用于精度要求较低的大型复杂零部件。在铜/钢双金属材料增材制造过程中,界面处易形成显微组织分布不均匀、界面晶粒尺寸差异较大等现象,导致界面处产生应力集中,从而造成材料...     

基于CMT技术的铝合金电弧增材制造研究现状

由于铝合金的应用领域较为广泛,使其增材制造技术成为了研究热点。CMT技术作为一种新型焊接工艺,焊接过程中弧长控制较为精确,其热输入量小、飞溅少等工艺特点非常适合铝合金等低熔点金属的增材制造,因此,铝合金CMT增材制造技术成为了近年来国内外各研究机构的研究热点。从控形控性的角度分析了国内外相关研究机构的研究方向,重点综述了焊接速度、送丝速度、CMT工艺等工艺参数和热处理对成形件形貌及性能的影响,同时概述了铝合金CMT电弧增材制造中尺寸控制、组织性能、气孔缺陷等方向的研究工作。借此指出,基于CMT技术的铝合金电弧增材制造技术的相关研究工作仍主要聚焦于试验研究阶段,并未深入到成形机理的探究。该领域的研究工作应更深入、系统地从成形尺寸精度控制、控制气孔缺陷、组织演变规律及性能优化等角度展开,力求加速推进该技术在现代制造业的应用。     

Remedy for round-off error accumulation observed in a neutron diffusion calculation using the multiple reciprocity boundary element method

A round-off error accumulation is observed in a multiple reciprocity computation for a fission neutron source iteration problem when a certain convergence condition is not satisfied. The present paper presents a reformulation of the multiple reciprocity method to remove the numerical problem. The neutron diffusion equation (NDE) is arranged using Wielandt's spectral shift technique in such a way that the convergence condition is always satisfied through source iterations. The boundary integral equation in this case requires the fundamental solution to the standard Helmholtz equation, while the fundamental solution corresponding to the correspoding to the original NDE was one to the modified Helmholtz equation. Except for this, the new multiple reciprocity formulation is identical to the original one for the fission source iteration problems. Some test calculation results indicate that a rapid and stable convergence can be realized using the new method and no round-off error accumulation is observed any more.     

Prediction of solidification behaviour and microstructure of Ni based alloys obtained by casting and direct additive laser growth

Numerical tools are now used widely in the prediction of material properties necessary in order to gain a better understanding of the relationship between material properties and performance, to improve the reliability of processes and the quality of the final product, and to reduce costs, waste and energy use. In this paper, the solidification properties and the microstructure of some commercial Ni based alloys were analysed and predicted numerically using the ProCAST software. The microstructure of a sample obtained by the direct additive laser growth, a new additive manufacturing technique based on the selective laser melting, is presented and discussed. Numerical approaches and software packages that can be used to model additive manufacturing processes are discussed and critically analysed.     

Additive Design and Manufacturing of Jet Engine Parts

The additive design (AD) and additive manufacturing (AM) of jet engine parts will revolutionize the traditional aerospace industry. The unique characteristics of AM, such as gradient materials and micro-structures, have opened up a new direction in jet engine design and manufacturing. Engineers have been liberated from many constraints associated with traditional methodologies and technologies. One of the most significant features of the AM process is that it can ensure the consistency of parts because it starts from point(s), continues to line(s) and layer(s), and ends with the competed part. Collaboration between design and manufacturing is the key to success in fields including aerodynamics, thermodynamics, structural integration, heat transfer, material development, and machining. Engineers must change the way they design a part, as they shift from the traditional method of “subtracting material” to the new method of “adding material” in order to manufacture a part. AD is not the same as designing for AM. A new method and new tools are required to assist with this new way of designing and manufacturing. This paper discusses in detail what is required in AD and AM, and how current problems can be solved.     

Bayesian Model Building From Small Samples of Disparate Data for Capturing In-Plane Deviation in Additive Manufacturing

ABSTRACT

Quality control of geometric shape deviation in additive manufacturing relies on statistical deviation models. However, resource constraints limit the manufacture of test shapes, and consequently impede the specification of deviation models for new shape varieties. We present an adaptive Bayesian methodology that effectively combines in-plane deviation data and models for a small sample of previously manufactured, disparate shapes to aid in the model specification of in-plane deviation for a broad class of new shapes. The power and simplicity of this general methodology is demonstrated with illustrative case studies on in-plane deviation modeling for polygons and straight edges in free-form shapes using only data and models for cylinders and a single regular pentagon. Our Bayesian approach facilitates deviation modeling in general, and thereby can help advance additive manufacturing as a high-quality technology. Supplementary materials for this article are available online.     

Multi-site impact response of S2-glass/epoxy composite laminates

High velocity transverse impact to laminated fiber reinforced composites is of interest in marine, military and civilian applications. Most studies in literature have addressed single point isolated impact events; while this work draws distinction in that we consider multi-site sequential and simultaneous impacts to composite structures. The overall objectives of this work were to investigate the response of laminated composites subjected to high velocity, multi-site impacts from a modeling and experimental viewpoint. Energy absorption, new surface creation, and failure mechanisms from sequential and simultaneous multi-site high velocity impacts are compared to assess additive and cumulative effects of these scenarios. Finite element modeling (LS-DYNA 3D) was used to gain insight into failure modes, energy absorption, and damage prediction. The modeling results correlated well with experimental data obtained from three layer laminates of vacuum assisted resin transfer molding (VARTM) processed S2-glass/SC-15 epoxy. The impact damage has been characterized using optical nondestructive evaluation (NDE) techniques. Specimens subjected to sequential impact exhibited average of 10% greater energy absorption and 18% increase in damage than specimens impacted simultaneously.     

光丝同轴激光增材制造研究进展

增材制造作为实现三维结构快速成形的技术,广泛用于航空航天、汽车交通等领域.当前,激光熔丝增材制造多依托于传统的激光焊接设备,采用旁轴送丝方式,在增材过程中,需调整激光头方向保证送丝和焊接头行进的相对方位,增大了复杂构件增材制造系统控制难度,损失了加工自由度.随着激光加工设备和技术的发展,近年来出现了一种可以解决上述问题...     

金属增材制造技术发展趋势综述

近年来金属增材制造技术的快速发展,使其在航空航天、医疗行业、汽车制造等领域得到了大量应用.本文简要介绍了金属增材制造的典型工艺、金属粉末和金属丝材的制备方法以及基于文献统计的方法分析金属增材制造目前的研究热点和发展趋势.结果 表明,金属增材制造技术在仿真设计、制造工艺、过程监控、质量评估、后续处理等领域还没有形成完善的...     

Defects and anomalies in powder bed fusion metal additive manufacturing

Metal additive manufacturing is a disruptive technology that is revolutionizing the manufacturing industry. Despite its unrivaled capability for directly fabricating metal parts with complex geometries, the wide realization of the technology is currently limited by microstructural defects and anomalies, which could significantly degrade the structural integrity and service performance of the product. Accurate detection, characterization, and prediction of these defects and anomalies have an important and immediate impact in manufacturing fully-dense and defect-free builds. This review seeks to elucidate common defects/anomalies and their formation mechanisms in powder bed fusion additive manufacturing processes. They could arise from raw materials, processing conditions, and post-processing. While defects/anomalies in laser welding have been studied extensively, their formation and evolution remain unclear. Additionally, the existence of powder in powder bed fusion techniques may generate new types of defects, e.g., porosity transferring from powder to builds. Practical strategies to mitigate defects are also addressed through fundamental understanding of their formation. Such explorations enable the validation and calibration of models and ease the process qualification without costly trial-and-error experimentation.     

Additive layered manufacturing: sectors of industrial application shown through case studies

In modern industry, mass production has migrated to third world countries. To be competitive, European companies are forced to rapidly switch towards manufacturing of short series of customised products with added value. In European industry, a great effort has been made in order to customise products and give them an added value by developing new fabrication technologies. Additive layered manufacturing (ALM), also known as rapid manufacturing (RM), is a powerful tool that offers the necessary competitiveness to European companies. ALM comprises the use of layer-by-layer manufacturing in order to build a part by addition of material. Fabrication is performed directly from the 3D CAD model, which is sliced into layers that are printed one upon the other. Also known as free form fabrication, additive fabrication ‘unlocks’ design potential since part design obeys functionality, pushing the limits of manufacturability. In this paper, the authors review ALM technologies and the state-of-the-art of ALM applications in tooling, biomedicine and lightweight structures for the automotive and aerospace sectors. The authors present their experience in industrial application of additive fabrication through various industrial technology transfer projects made to transfer ALM technology to SMEs. Various case studies are presented and the achieved benefits of ALM are shown.