|Author||: Michael Gouge,Pan Michaleris|
|Release Date||: 2017-08-03|
|ISBN 10||: 0128118210|
|Pages||: 294 pages|
Thermo-mechanical Modeling of Additive Manufacturing provides the background, methodology and description of modeling techniques to enable the reader to perform their own accurate and reliable simulations of any additive process. Part I provides an in depth introduction to the fundamentals of additive manufacturing modeling, a description of adaptive mesh strategies, a thorough description of thermal losses and a discussion of residual stress and distortion. Part II applies the engineering fundamentals to direct energy deposition processes including laser cladding, LENS builds, large electron beam parts and an exploration of residual stress and deformation mitigation strategies. Part III concerns the thermo-mechanical modeling of powder bed processes with a description of the heat input model, classical thermo-mechanical modeling, and part scale modeling. The book serves as an essential reference for engineers and technicians in both industry and academia, performing both research and full-scale production. Additive manufacturing processes are revolutionizing production throughout industry. These technologies enable the cost-effective manufacture of small lot parts, rapid repair of damaged components and construction of previously impossible-to-produce geometries. However, the large thermal gradients inherent in these processes incur large residual stresses and mechanical distortion, which can push the finished component out of engineering tolerance. Costly trial-and-error methods are commonly used for failure mitigation. Finite element modeling provides a compelling alternative, allowing for the prediction of residual stresses and distortion, and thus a tool to investigate methods of failure mitigation prior to building. Provides understanding of important components in the finite element modeling of additive manufacturing processes necessary to obtain accurate results Offers a deeper understanding of how the thermal gradients inherent in additive manufacturing induce distortion and residual stresses, and how to mitigate these undesirable phenomena Includes a set of strategies for the modeler to improve computational efficiency when simulating various additive manufacturing processes Serves as an essential reference for engineers and technicians in both industry and academia
|Author||: Jarred Heigel|
|Release Date||: 2015|
|Pages||: 329 pages|
Additive manufacturing (AM) enables parts to be built through the layer-by-layer addition of molten metal. In directed energy deposition (DED) AM, metal powder or wire is added into a melt pool that follows a pattern to fill in the cross section of the part. When compared to traditional manufacturing processes, AM has manyadvantages such as the ability to make internal features and to repair high-value parts. However, the large thermal gradients generated by AM result in plastic deformation. Thermo-mechanical models must be developed to predict the temperature and distortion produced by this process.Thermo-mechanical models have been developed for AM by several investigators. These models are often validated by measuring the temperatures during the deposition of a small part and the final distortion of the part. Unfortunately this is not a sufficientvalidation method for the non-linear thermo-mechanical model. Although good agreement between the thermal model and the temperatures measured during a small depositions can be achieved, it does not necessarily mean that the model will be accurate for an industrially relevant part that requires 10^2 - 10^4 tracks and hours of processing time. The relatively small deviations between the model and the validation will propagate when modeling large depositions and could produce inaccurate results. The errors in a large part will be increased further if the assumptions made of thethermal boundary conditions are not appropriate for the system.The objective of this work is to develop and experimentally validate thermo-mechanical models for DED. Experiments are performed to characterize the distortion induced by laser cladding. The depositions require many tracks and nearly an hour of processing time, during which the temperature and the deflection are measured in situ so that the response of the plate to each deposition track is understood. Measurements are then made of the convection caused by two different laser deposition heads. Thermo-mechanical models are developed by implementing the measured rate of convective heat transfer and the temperature dependent material properties. The models are validated using in situ measurements of the temperatureand the deflection generated during the process, as well as post-process measurements of the residual stress and the distortedshape. Finally, experiments and models are used to investigate the impact of feedstock selection, either powder or wire, on the DEDprocess.
|Author||: Yi Shu|
|Release Date||: 2020|
|Pages||: 329 pages|
Additive manufacturing (AM) has introduced new possibilities of creating sophisticated designs and structures. Selective Laser Melting (SLM) is an AM technique where structures are fabricated by selectively melting and fusing powder layers. In SLM, melt pools are induced by a laser beam moving on the top surface of a substrate submerged in a powder bed. Mechanical properties of additively manufactured metallic parts are known to be strongly affected by thermal histories, and residual stresses arise due to large temperature gradients. Thermo-mechanical models would help to gain information about both, which is usually hard to obtain. This thesis focuses on examining how well thermal histories and residual stresses in metallic substrates around laser-induced melt pools can be computed by thermo-mechanical models, through experiments on substrates of 17-4PH Stainless Steel (SS) and Ti-6Al-4V. In the first set of experiments, one of two different laser beams moves with constant velocity and power over substrates of 17-4PH SS or Ti-6Al-4V. The substrates are sectioned and etched to expose melt pool traces. In the second set of experiments, single-pass lasers move with constant velocity and power on top surfaces of 17-4PH SS substrates. The time evolution of the deflection of substrates are recorded with a high speed camera. Two types of heat transfer models (accounting for and not accounting for convective heat transfer through fluid flow) reproduced the melt pool traces in the first set of experiments. Predicted thermal histories were critically analyzed. As an extension, how well the model accounting for convective heat transfer reproduced the effect of a substrate edge on the melt pool was examined. Later, the model without convective heat transfer was applied to real-time ultrasonic monitoring of a melt pool in metallic substrates. For the second set of experiments, the model based on heat conduction and elasto-viscoplasticity reproduced the time evolution of deflection of 17-4PH SS substrates. The contributions of this thesis are as follows. Through experiments with various combinations of laser power, scanning speed, power density distribution and metallic material, we show that simply reproducing melt pool traces is insufficient to determine thermal histories. Specifically, for a non-axisymmetric laser beam, three-dimensional melt pool shapes can be disparate even if their two-dimensional traces are very similar. Convective heat transfer in laser-induced melt pools cannot be completely ignored, otherwise there may be inconsistencies between the model and experiment conditions, as well as distortion of thermal histories related to phase transformation. With experiments of laser melting tracks near edges of substrates, we demonstrate that the model accounting for convective heat transfer can consistently reproduce melt pool traces affected by a substrate's edge. We have proven the existence of scattering waves by the presence of a melt pool through simulation, for a possibility of monitoring the state of laser-induced melt pool in real-time with ultrasound. We have designed deflection experiments of metallic substrates monitored by a high-speed camera, which would benefit calibrating thermo-mechanical models for residual stresses because of the substrate's simple thermal and mechanical history. By reproducing the deflection experiments with the model based on heat conduction and elasto-viscoplasticity, we conclude that the solid state phase transformation plays an indispensable role in the evolution of residual stresses of 17-4PH SS. We also highlight the necessity of monitoring time evolution instead of the end state when evaluating models for residual stress of alloys with volume change during phase transformation.
|Author||: C. V. Nielsen,W. Zhang,L. M. Alves,N. Bay,Niels Bay|
|Publisher||: Springer Science & Business Media|
|Release Date||: 2012-10-08|
|ISBN 10||: 1447146433|
|Pages||: 120 pages|
Modeling of Thermo-Electro-Mechanical Manufacturing Processes with Applications in Metal Forming and Resistance Welding provides readers with a basic understanding of the fundamental ingredients in plasticity, heat transfer and electricity that are necessary to develop and proper utilize computer programs based on the finite element flow formulation. Computer implementation of a wide range of theoretical and numerical subjects related to mesh generation, contact algorithms, elasticity, anisotropic constitutive equations, solution procedures and parallelization of equation solvers is comprehensively described. Illustrated and enriched with selected examples obtained from industrial applications, Modeling of Thermo-Electro-Mechanical Manufacturing Processes with Applications in Metal Forming and Resistance Welding works to diminish the gap between the developers of finite element computer programs and the professional engineers with expertise in industrial joining technologies by metal forming and resistance welding.
|Author||: Bert Verlinden,Julian Driver,Indradev Samajdar,Roger D. Doherty|
|Release Date||: 2007-06-07|
|ISBN 10||: 9780080544489|
|Pages||: 560 pages|
Thermo-Mechanical Processing of Metallic Materials describes the science and technology behind modern thermo-mechanical processing (TMP), including detailed descriptions of successful examples of its application in the industry. This graduate-level introductory resource aims to fill the gap between two scientific approaches and illustrate their successful linkage by the use of suitable modern case studies. The book is divided into three key sections focusing on the basics of metallic materials processing. The first section covers the microstructural science base of the subject, including the microstructure determined mechanical properties of metals. The second section deals with the current mechanical technology of plastic forming of metals. The concluding section demonstrates the interaction of the first two disciplines in a series of case studies of successful current TMP processing and looks ahead to possible new developments in the field. This text is designed for use by graduate students coming into the field, for a graduate course textbook, and for Materials and Mechanical Engineers working in this area in the industry. * Covers both physical metallurgy and metals processing * Links basic science to real everyday applications * Written by four internationally-known experts in the field
|Author||: Igor Shishkovsky|
|Publisher||: BoD – Books on Demand|
|Release Date||: 2018-07-11|
|ISBN 10||: 1789233887|
|Pages||: 154 pages|
Freedoms in material choice based on combinatorial design, different directions of process optimization, and computational tools are a significant advantage of additive manufacturing technology. The combination of additive and information technologies enables rapid prototyping and rapid manufacturing models on the design stage, thereby significantly accelerating the design cycle in mechanical engineering. Modern and high-demand powder bed fusion and directed energy deposition methods allow obtaining functional complex shapes and functionally graded structures. Until now, the experimental parametric analysis remains as the main method during AM optimization. Therefore, an additional goal of this book is to introduce readers to new modeling and material's optimization approaches in the rapidly changing world of additive manufacturing of high-performance metals and alloys.
|Author||: K. C. Mills|
|Publisher||: Woodhead Publishing|
|Release Date||: 2002|
|ISBN 10||: 9780871707536|
|Pages||: 244 pages|
Product miniaturization is a trend for facilitating product usage, enabling product functions to be implemented in microscale geometries, and aimed at reducing product weight, volume, cost and pollution. Driven by ongoing miniaturization in diverse areas, including medical devices, precision equipment, communication devices, micro-electromechanical systems and microsystems technology, the demands for micro metallic products have been tremendously increased. Such a trend requires the development of advanced technology for the micromanufacturing of metallic materials, with regard to producing high-quality micro metallic products that possess excellent dimensional tolerances, the required mechanical properties and improved surface quality. Micromanufacturing differs from conventional manufacturing technology in terms of materials, processes, tools, and machines and equipment, due to the miniaturization nature of the whole micromanufacturing system, which challenges the rapid development of micromanufacturing technology. Such a background has prompted and encouraged us to publish a scholarly book on the topic of the micromanufacturing of metallic materials, with the purpose of providing readers with a valuable document that can be used in the research and development of micromanufacturing technology. This book will be useful for both theoretical and applied research aimed at micromanufacturing technology, and will serve as an important research tool, providing knowledge to be returned to the community not only as valuable scientific literature, but also as technology, processes and productivities.
|Author||: Jing Zhang,Yeon-Gil Jung|
|Release Date||: 2018-05-17|
|ISBN 10||: 0128123273|
|Pages||: 362 pages|
Additive Manufacturing: Materials, Processes, Quantifications and Applications is designed to explain the engineering aspects and physical principles of available AM technologies and their most relevant applications. It begins with a review of the recent developments in this technology and then progresses to a discussion of the criteria needed to successfully select an AM technology for the embodiment of a particular design, discussing material compatibility, interfaces issues and strength requirements. The book concludes with a review of the applications in various industries, including bio, energy, aerospace and electronics. This book will be a must read for those interested in a practical, comprehensive introduction to additive manufacturing, an area with tremendous potential for producing high-value, complex, individually customized parts. As 3D printing technology advances, both in hardware and software, together with reduced materials cost and complexity of creating 3D printed items, these applications are quickly expanding into the mass market. Includes a discussion of the historical development and physical principles of current AM technologies Exposes readers to the engineering principles for evaluating and quantifying AM technologies Explores the uses of Additive Manufacturing in various industries, most notably aerospace, medical, energy and electronics
Computational Welding Mechanics (CWM) provides readers with a complete introduction to the principles and applications of computational welding including coverage of the methods engineers and designers are using in computational welding mechanics to predict distortion and residual stress in welded structures, thereby creating safer, more reliable and lower cost structures. Drawing upon years of practical experience and the study of computational welding mechanics the authors instruct the reader how to: - understand and interpret computer simulation and virtual welding techniques including an in depth analysis of heat flow during welding, microstructure evolution and distortion analysis and fracture of welded structures, - relate CWM to the processes of design, build, inspect, regulate, operate and maintain welded structures, - apply computational welding mechanics to industries such as ship building, natural gas and automobile manufacturing. Ideally suited for practicing engineers and engineering students, Computational Welding Mechanics is a must-have book for understanding welded structures and recent technological advances in welding, and it provides a unified summary of recent research results contributed by other researchers.
Additive manufacturing (AM) is a fast-growing sector with the ability to evoke a revolution in manufacturing due to its almost unlimited design freedom and its capability to produce personalised parts locally and with efficient material use. AM companies, however, still face technological challenges such as limited precision due to shrinkage, built-in stresses and limited process stability and robustness. Moreover, often post-processing is needed due to high roughness and remaining porosity. Qualified, trained personnel are also in short supply. In recent years, there have been dramatic improvements in AM design methods, process control, post-processing, material properties and material range. However, if AM is going to gain a significant market share, it must be developed into a true precision manufacturing method. The production of precision parts relies on three principles: Production is robust (i.e. all sensitive parameters can be controlled). Production is predictable (for example, the shrinkage that occurs is acceptable because it can be predicted and compensated in the design). Parts are measurable (as without metrology, accuracy, repeatability and quality assurance cannot be known). AM of metals is inherently a high-energy process with many sensitive and inter-related process parameters, making it susceptible to thermal distortions, defects and process drift. The complete modelling of these processes is beyond current computational power, and novel methods are needed to practicably predict performance and inform design. In addition, metal AM produces highly textured surfaces and complex surface features that stretch the limits of contemporary metrology. With so many factors to consider, there is a significant shortage of background material on how to inject precision into AM processes. Shortage in such material is an important barrier for a wider uptake of advanced manufacturing technologies, and a comprehensive book is thus needed. This book aims to inform the reader how to improve the precision of metal AM processes by tackling the three principles of robustness, predictability and metrology, and by developing computer-aided engineering methods that empower rather than limit AM design. Richard Leach is a professor in metrology at the University of Nottingham and heads up the Manufacturing Metrology Team. Prior to this position, he was at the National Physical Laboratory from 1990 to 2014. His primary love is instrument building, from concept to final installation, and his current interests are the dimensional measurement of precision and additive manufactured structures. His research themes include the measurement of surface topography, the development of methods for measuring 3D structures, the development of methods for controlling large surfaces to high resolution in industrial applications and the traceability of X-ray computed tomography. He is a leader of several professional societies and a visiting professor at Loughborough University and the Harbin Institute of Technology. Simone Carmignato is a professor in manufacturing engineering at the University of Padua. His main research activities are in the areas of precision manufacturing, dimensional metrology and industrial computed tomography. He is the author of books and hundreds of scientific papers, and he is an active member of leading technical and scientific societies. He has been chairman, organiser and keynote speaker for several international conferences, and received national and international awards, including the Taylor Medal from CIRP, the International Academy for Production Engineering.
|Author||: Antoni Niepokolczycki,Jerzy Komorowski|
|Release Date||: 2019-07-03|
|ISBN 10||: 3030215032|
|Pages||: 1164 pages|
This book gathers papers presented at the 36th conference and 30th Symposium of the International Committee on Aeronautical Fatigue and Structural integrity. Focusing on the main theme of “Structural Integrity in the Age of Additive Manufacturing”, the chapters cover different aspects concerning research, developments and challenges in this field, offering a timely reference guide to designers, regulators, manufacturer, and both researchers and professionals of the broad aerospace community.