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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
The objective of this work is to experimentally validate thermal andmechanical finite element models of metallic parts produced usingadditive manufacturing (AM) processes. AM offers advantages overother manufacturing processes due the fact that it can produce netand near-net shapes directly from a digital drawing file. Parts canbe produced on a layer by layer basis by melting wire or powdermetal using a laser or an electron beam. The material then cools andsolidifies to form a fully dense geometry. Unfortunately the largethermal gradients cause a buildup of residual stress often takingparts out of tolerance or causing failure by cracking ordelamination. To successfully reduce distortion and residual stressin metallic AM parts without expensive and time consuming trial anderror iterations, an experimentally validated physics based model isneeded.In this work finite element (FE) models for the laser directedenergy deposition (LDED), the Electron Beam Directed Manufacture(EBDM) process, and the Laser Powder-Bed Fusion (LPBF) process aredeveloped and validated. In situ distortion and temperaturemeasurements are taken during the LDED processing of both Ti-6Al-4Vand Inconel 625. The in situexperimental results are used in addition to post-process residualstress measurements to validate a thermo-mechanical model for eachalloy. The results show that each material builds distortiondifferently during AM processing, a previously unknown effect thatmust be accounted for in the model. The thermal boundary conditionsin the model are then modified to allow for the modeling of the EBDMprocess. The EBDM model is validated against in situ temperature anddistortion measurements as well as post-process residual stressmeasurements taken on a single bead wide Ti-6Al-4V wall build.Further model validation is provided by comparing the predictedmechanical response of a large EBDM aerospace component consistingof several thousand deposition tracks to post-process distortionmeasurements taken on the actual part. Several distortion mitigationtechniques are also investigated using an FE model. The findings areused to reduce the maximum distortion present on the largeindustrial aerospace component by 91~\%. Finally, the modeling workfor the LDED and the EBDM processes is extended to Laser Powder-BedFusion (LPBF) processing of Inconel718. The necessary boundary conditions and material properties toinclude in the models are identified by comparing the model with insitu experimental results.
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) 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.
This engaging volume presents the exciting new technology of additive manufacturing (AM) of metal objects for a broad audience of academic and industry researchers, manufacturing professionals, undergraduate and graduate students, hobbyists, and artists. Innovative applications ranging from rocket nozzles to custom jewelry to medical implants illustrate a new world of freedom in design and fabrication, creating objects otherwise not possible by conventional means. The author describes the various methods and advanced metals used to create high value components, enabling readers to choose which process is best for them. Of particular interest is how harnessing the power of lasers, electron beams, and electric arcs, as directed by advanced computer models, robots, and 3D printing systems, can create otherwise unattainable objects. A timeline depicting the evolution of metalworking, accelerated by the computer and information age, ties AM metal technology to the rapid evolution of global technology trends. Charts, diagrams, and illustrations complement the text to describe the diverse set of technologies brought together in the AM processing of metal. Extensive listing of terms, definitions, and acronyms provides the reader with a quick reference guide to the language of AM metal processing. The book directs the reader to a wealth of internet sites providing further reading and resources, such as vendors and service providers, to jump start those interested in taking the first steps to establishing AM metal capability on whatever scale. The appendix provides hands-on example exercises for those ready to engage in experiential self-directed learning.
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.
METAL ADDITIVE MANUFACTURING A comprehensive review of additive manufacturing processes for metallic structures Additive Manufacturing (AM)—also commonly referred to as 3D printing—builds three-dimensional objects by adding materials layer by layer. Recent years have seen unprecedented investment in additive manufacturing research and development by governments and corporations worldwide. This technology has the potential to replace many conventional manufacturing processes, enable the development of new industry practices, and transform the entire manufacturing enterprise. Metal Additive Manufacturing provides an up-to-date review of all essential physics of metal additive manufacturing techniques with emphasis on both laser-based and non-laser-based additive manufacturing processes. This comprehensive volume covers fundamental processes and equipment, governing physics and modelling, design and topology optimization, and more. The text adresses introductory, intermediate, and advanced topics ranging from basic additive manufacturing process classification to practical and material design aspects of additive manufacturability. Written by a panel of expert authors in the field, this authoritative resource: Provides a thorough analysis of AM processes and their theoretical foundations Explains the classification, advantages, and applications of AM processes Describes the equipment required for different AM processes for metallic structures, including laser technologies, positioning devices, feeder and spreader mechanisms, and CAD software Discusses the opportunities, challenges, and current and emerging trends within the field Covers practical considerations, including design for AM, safety, quality assurance, automation, and real-time control of AM processes Includes illustrative cases studies and numerous figures and tables Featuring material drawn from the lead author’s research and professional experience on laser additive manufacturing, Metal Additive Manufacturing is an important source for manufacturing professionals, research and development engineers in the additive industry, and students and researchers involved in mechanical, mechatronics, automatic control, and materials engineering and science.
* Numerous line drawings with consistent format and units allow easy comparison of the behavior of a very wide range of materials * Transmission electron micrographs provide a direct insight in the basic microstructure of metals deforming at high temperatures * Extensive literature review of over 1000 references provide an excellent reference document, and a very balanced discussion Understanding the strength of materials at a range of temperatures is critically important to a huge number of researchers and practitioners from a wide range of fields and industry sectors including metallurgists, industrial designers, aerospace R&D personnel, and structural engineers. The most up-to date and comprehensive book in the field, Fundamentals of Creep in Metals and Alloys discusses the fundamentals of time-dependent plasticity or creep plasticity in metals, alloys and metallic compounds. This is the first book of its kind that provides broad coverage of a range of materials not just a sub-group such as metallic compounds, superalloys or crystals. As such it presents the most balanced view of creep for all materials scientists. The theory of all of these phenomena are extensively reviewed and analysed in view of an extensive bibliography that includes the most recent publications in the field. All sections of the book have undergone extensive peer review and therefore the reader can be sure they have access to the most up-to-date research, fully interrogated, from the world’s leading investigators. · Numerous line drawings with consistent format and units allow easy comparison of the behavior of a very wide range of materials· Transmission electron micrographs provide a direct insight in the basic microstructure of metals deforming at high temperatures· Extensive literature review of over 1000 references provide an excellent reference document, and a very balanced discussion