Author: Bin ShiPublisher:
ISBN:
Category : Metal-cutting
Languages : en
Pages : 182
Book Description
Identification of the Material Constitutive Equation for Simulation of the Metal Cutting Process
Author: Bin ShiPublisher:
ISBN:
Category : Metal-cutting
Languages : en
Pages : 182
Book Description
Modeling the Material Behavior under Metal Cutting Conditions
Author: Marvin HardtPublisher: Apprimus Wissenschaftsverlag
ISBN: 3985550611
Category : Technology & Engineering
Languages : en
Pages : 204
Book Description
The scientific goal of the present work was to model the workpiece material behavior of steels in the metal cutting process depending on the occurring thermo-mechanical loads. The results of this work shall make a significant contribution to the predictive process design of the cutting process by means of Finite Element (FE) simulations for the virtual representation of the reality in the sense of the digital twin. To achieve the objective, extensive empirical examinations were conducted in a first step, which included conventional material scientific and orthogonal cutting tests. This enabled the establishment of a database of the workpiece response with increasing thermo-mechanical loads. During the orthogonal cutting examinations, integral and locally resolved process results were measured, which were used as calibration and validation variables in the modeling of the workpiece material behavior. By extending an established friction test bench with a workpiece pre-heating system, the friction conditions between tool and workpiece could be investigated under conditions equivalent to the cutting process. Based on the experimental results, a friction model was derived, in which the observed effects of thermal softening and the localized adhesion-induced increase in the apparent friction coefficient were superposed. A phenomenological material model was developed to describe the workpiece material behavior in the cutting process. The formulation of the material mode was developed based on empirical examinations as well as results from the state of the art. The material model was implemented in an FE-chip formation simulation using a subroutine. A hybrid optimization algorithm was developed to inversely determine the material model parameters. By means of the optimization algorithm, the material model parameters could be systematically determined inversely, taking the experimentally determined process observables into account. An automated procedure linked to a user interface lowered the entry hurdle for industrial companies and unexperienced users of FE-simulations and reduced the computational effort for the inverse parameter determination to about 10 days of computational execution time. The quality of the developed models and the determined model parameters were further verified by a final deduction step using the industrial example of face turning.
Advanced Machining Processes
Author: Angelos P. MarkopoulosPublisher: CRC Press
ISBN: 1315305259
Category : Technology & Engineering
Languages : en
Pages : 271
Book Description
Modeling and machining are two terms closely related. The benefits of the application of modeling on machining are well known. The advances in technology call for the use of more sophisticated machining methods for the production of high-end components. In turn, more complex, more suitable, and reliable modeling methods are required. This book pertains to machining and modeling, but focuses on the special aspects of both. Many researchers in academia and industry, who are looking for ways to refine their work, make it more detailed, increase their accuracy and reliability, or implement new features, will gain access to knowledge in this book that is very scare to find elsewhere.
Mechanics of Materials in Modern Manufacturing Methods and Processing Techniques
Author: Vadim V. SilberschmidtPublisher: Elsevier
ISBN: 0128182334
Category : Technology & Engineering
Languages : en
Pages : 465
Book Description
Mechanics of Materials in Modern Manufacturing Methods and Processing Techniques provides a detailed overview of the latest developments in the mechanics of modern metal forming manufacturing. Focused on mechanics as opposed to process, it looks at the mechanical behavior of materials exposed to loading and environmental conditions related to modern manufacturing processes, covering deformation as well as damage and fracture processes. The book progresses from forming to machining and surface-treatment processes, and concludes with a series of chapters looking at recent and emerging technologies. Other topics covered include simulations in autofrettage processes, modeling strategies related to cutting simulations, residual stress caused by high thermomechanical gradients and pultrusion, as well as the mechanics of the curing process, forging, and cold spraying, among others. Some non-metallic materials, such as ceramics and composites, are covered as well. Synthesizes the latest research in the mechanics of modern metal forming processes Suggests theoretical models and numerical codes to predict mechanical responses Covers mechanics of shot peening, pultrusion, hydroforming, magnetic pulse forming Considers applicability of different materials and processes for optimum performance
Metal Cutting Mechanics
Author: Viktor P. AstakhovPublisher: CRC Press
ISBN: 1466571772
Category : Science
Languages : en
Pages : 321
Book Description
Metal Cutting Mechanics outlines the fundamentals of metal cutting analysis, reducing the extent of empirical approaches to the problems as well as bridging the gap between design and manufacture. The author distinguishes his work from other works through these aspects: considering the system engineering of the cutting process id
Inverse identification of material parameters from machining processes
Author: Aviral ShrotPublisher: Cuvillier Verlag
ISBN: 3736943970
Category : Technology & Engineering
Languages : en
Pages : 264
Book Description
Kurzbeschreibung Die Finite-Elemente-Simulation ist ein wichtiges numerisches Werkzeug zur Verbesserung des Verständnisses des Spanbildungsprozesses. Mit dieser Methode können komplexe Bearbeitungsprozesse mit komplexen Span-Morphologien simuliert werden. Eine wichtige Herausforderung bei der Modellierung spanender Bearbeitungsverfahren ist, dass keine Materialparameter bekannt sind, die das Werkstoffverhalten unter stark variierenden Dehnungen, Dehnungsgeschwindigkeiten und Temperaturen vorhersagen können. Während eines Fließspanbildungsprozesses können Dehnungen von bis zu 200%, sowie Dehnungsgeschwindigkeiten in der Größenordnung von 105 s−1 und Temperaturerhöhungen im Bereich von mehreren 100 ◦C auftreten. Im Vergleich dazu können experimentelle Methoden wie der Split-Hopkinson-Pressure-Bar-Test (SHPB) in der Regel Dehnungen von bis zu 50% und Dehnungsgeschwindigkeiten in der Größenordnung von 103 s−1 erreichen. Diese Tests können dazu genutzt werden, um mittels Datenanpassungsmethoden die Materialparameter aus den experimentellen Daten zu bestimmen. Aufgrund der großen Extrapolationsbereiche stimmen die Ergebnisse der Zerspanungssimulationen in der Regel nicht besonders gut mit den experimentellen Ergebnissen überein. Zuerst werden die Schwierigkeiten der Verwendung der Materialparameter, die aus Standard-Experimenten bestimmt werden, für die Zerspanungssimulationen von drei verschiedenen Werkstoffen aufgezeigt. Die Johnson-Cook-Parameter werden für Ti-15-3-3-3, Ti-6246 und Alloy 625 aus SHPB-Experimenten bestimmt. Diese werden anschließend verwendet, um die Spanbildung mit Hilfe der Finite-Elemente-Methode zu simulieren. Für Ti-15-3-3-3 und Ti-6246 wird die Bildung eines segmentierten Spans beobachtet. Für Alloy 625 wird die Materialfestigkeit bei hohen Dehnungen vom Johnson-Cook-Modell überschätzt, wodurch in der Simulation die Bildung eines Fließspans vorhergesagt wird. Daher wird ein modifiziertes Johnson-Cook-Modell für die Zerspanungssimulationen verwendet, resultierend in einer segmentierten Spanform. Die durchschnittlichen Schnittkräfte werden in den drei Fällen im Rahmen von 20% der experimentell erhaltenen Werte vorhergesagt. Es gibt deutliche Unterschiede in den vorhergesagten und den experimentell ermittelten Spanformen. Diese Unterschiede können auf die Schwierigkeit der Vorhersage des Materialverhaltens unter den während spanender Bearbeitung vorherrschenden Bedingungen zurückgeführt werden. Dieses Problem wird durch die Verwendung einer inversen Parameterbestimmungsmethode beseitigt, da auf diese Weise die Materialparameter direkt aus den Zerspanungsprozessen identifiziert werden. Die Spanformen und die Schnittkräfte der Simulation werden durch die systematische Variation der Materialparameter mit den entsprechenden Werten aus den Standardexperimenten abgestimmt. Die Robustheit des Verfahrens wird durch die Identifizierung von Parametern für zwei verschiedene Materialien, sowie die Durchführung von Optimierungen von verschiedenen Ausgangspunkten getestet. Ebenfalls werden Studien durchgeführt, um die Konvergenz zu verbessern, und um den Berechnungsaufwand zu reduzieren. Die Lösung, die aus dem inversen Identifikationsalgorithmus vorhergesagt wird, kann ebenfalls durch die Kenntnis des Einflusses der Spannungs-Dehnungs-Kurven auf die Spanformen und die Schnittkräfte verbessert werden, was auch den Berechnungsaufwand verringern kann. Es hat sich gezeigt, dass viele Parametersätze identifiziert werden können, die ähnliche Spanformen und Schnittkräfte zur Folge haben. Dies ist darin begründet, dass alle Parametersätze im Gebiet der Zerspanungverfahren die gleiche Fließspannungskurve wiedergeben. Um Parameter zu bestimmen, die über einen möglichst großen Bereich gültig sind, werden sich stark unterscheidende Schneidbedingungen für den Identifikationsprozess gewählt. Description Finite element simulation has become an important tool in understanding the chip formation process. Complex machining processes with complex chip morphologies have been simulated this way. An important challenge in the modelling of machining processes is that material parameters are not available which can robustly predict the material behaviour at large ranges of strains, strain rates and temperatures. During a continuous chip formation process, strains can reach up to 200%, strain rates can be of the order of 105 s−1 and temperature variation can be in the order of hundreds of degrees. In comparison, state-of-the-art experimental methods such as the Split Hopkinson Pressure Bar (SHPB) tests can usually reach strains of up to 50% and strain rates of the order of 103 s−1. Data fitting techniques are then used to identify material parameters from the experimental data. Due to the large extrapolations involved, the machining simulation results do not robustly match the experimental results. The difficulty of using the material parameters determined from standard experiments for machining simulations is first shown for three different materials. The Johnson-Cook material parameters are obtained for Ti-15-3-3-3, Ti-6246 and Alloy 625 from SHPB experiments. These are then used to simulate the chip formation using the finite element method. For Ti-15-3-3-3 and Ti-6246, segmented chip formation is observed. For Alloy 625, the Johnson-Cook model overestimates the material strength at high strains and the resulting machining simulation gives rise to a continuous chip. Therefore a modified Johnson-Cook model is used for machining simulations which forms segmented chip. The average cutting force in the three cases are predicted within 20% of the experimentally obtained values. There are significant differences in the predicted chip shapes and the experimentally obtained chip shapes. These differences can be attributed to the difficulty of predicting the material behaviour at conditions prevailing during machining. An inverse identification method is used to identify material parameters directly from machining processes to resolve this problem. The chip shapes and the cutting forces are matched to a standard by systematically varying the material parameters. The robustness of the method is tested by identifying parameters for two different materials and conducting optimisations from different starting points. Studies are also conducted to improve the convergence and reduce the computational expense. The knowledge of the effect of stress-strain curves on the chip shapes and the cutting forces can also be used to improve the optimised solution predicted by the inverse identification algorithm. This can lead to reduction in the computational expense. It is observed during the identification process that a number of parameter sets can be found which give rise to similar chips and cutting forces. This is because all the different parameter sets represent the same flow stress curve in the domain of machining. In order that the identified parameters are valid over a large machining domain, widely varying cutting conditions are chosen for the identification process.
Metal Machining
Author: P.R.N. ChildsPublisher: Butterworth-Heinemann
ISBN: 0080524028
Category : Technology & Engineering
Languages : en
Pages : 420
Book Description
Metal machining is the most widespread metal-shaping process in the mechanical manufacturing industry. World-wide investment in metal machining tools increases year on year - and the wealth of nations can be judged by it. This text - the most up-to-date in the field - provides in-depth discussion of the theory and application of metal machining at an advanced level. It begins with an overview of the development of metal machining and its role in the current industrial environment and continues with a discussion of the theory and practice of machining. The underlying mechanics are analysed in detail and there are extensive chapters examining applications through a discussion of simulation and process control. "Metal Machining: Theory and Applications" is essential reading for senior undergraduates and postgraduates specialising in cutting technology. It is also an invaluable reference tool for professional engineers. Professors Childs, Maekawa, Obikawa and Yamane are four of the leading authorities on metal machining and have worked together for many years. Of interest to all mechanical, manufacturing and materials engineers Theoretical and practical problems addressed
Author: Lei Pang
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