Dynamic Plasticity of Metals

Dynamic Plasticity of Metals

[23] H.G. Hopkins : Engineering Plasticity, p. 277, (University Press, Cambridge, ... [25] L.E. Malvern : Behavior of Materials under Dynamic Loading, p.

Author: John D. Campbell

Publisher: Springer

ISBN: 9783709128480

Category: Technology & Engineering

Page: 92

View: 643

Categories: Technology & Engineering

Dynamic plasticity of metals

Dynamic plasticity of metals

Author: John Douglas Sutherland Campbell Argyll

Publisher:

ISBN: OCLC:630610754

Category: Deformations (Mechanics)

Page: 92

View: 693

Categories: Deformations (Mechanics)

Technological Perspectives from Two Decades of Fundamental Research in Dynamic Plasticity

Technological Perspectives from Two Decades of Fundamental Research in Dynamic Plasticity

This work includes the results obtained for the loading and unloading response of the fully annealed solid, a general theory of plasticity, the dynamic plastic limit, the experimental study of dynamic plasticity and the evolution of proper ...

Author: James F. Bell

Publisher:

ISBN: OCLC:227369615

Category:

Page: 108

View: 535

The report presents twenty-five years of systematic study of the physics of large deformation and, in particular, of dynamic plasticity of metals. This work includes the results obtained for the loading and unloading response of the fully annealed solid, a general theory of plasticity, the dynamic plastic limit, the experimental study of dynamic plasticity and the evolution of proper constitutive equations.
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The Plasticity of Metals at the Sub micrometer Scale and Dislocation Dynamics in a Thin Film

The Plasticity of Metals at the Sub micrometer Scale and Dislocation Dynamics in a Thin Film

[4] Seok-Woo Lee, William D. Nix, “Geometrical analysis on 3D dislocation dynamics simulation of FCC micro pillar plasticity”, Materials Science and ...

Author:

Publisher: Stanford University

ISBN: STANFORD:tf313qt3147

Category:

Page:

View: 574

Nanotechnology has played a significant role in the development of useful engineering devices and in the synthesis of new classes of materials. For the reliable design of devices and for structural applications of materials with micro- or nano-sized features, nanotechnology has always called for an understanding of the mechanical properties of materials at small length scales. Thus, it becomes important to develop new experimental techniques to allow reliable mechanical testing at small scales. At the same time, the development of computational techniques is necessary to interpret the experimentally observed phenomena. Currently, microcompression testing of micropillars, which are fabricated by focused-ion beam (FIB) milling, is one of the most popular experimental methods for measuring the mechanical properties at the micrometer scale. Also, dislocation dynamics codes have been extensively developed to study the local evolution of dislocation structures. Therefore, we conducted both experimental and theoretical studies that shed new light on the factors that control the strength and plasticity of crystalline materials at the sub-micrometer scale. In the experimental work, we produced gold nanopillars by focused-ion beam milling, and conducted microcompression tests to obtain the stress-strain curves. Firstly, the size effects on the strength of gold nanopillars were studied, and "Smaller is Stronger" was observed. Secondly, we tried to change the dislocation densities to control the strength of gold nanopillars by prestraining and annealing. The results showed that prestraining dramatically reduces the flow strength of nanopillars while annealing restores the strength to the pristine levels. Transmission electron microscopy (TEM) revealed that the high dislocation density (~1015 m-2) of prestrained nanopillars significantly decreased after heavy plastic deformation. In order to interpret this TEM observation, potential dislocation source structures were geometrically analyzed. We found that the insertion of jogged dislocations before relaxation or enabling cross-slip during plastic flow are prerequisites for the formation of potentially strong natural pinning points and single arm dislocation sources. At the sub-micron scale, these conditions are most likely absent, and we argue that mobile dislocation starvation would occur naturally in the course of plastic flow. Two more outstanding issues have also been studied in this dissertation. The first involves the effects of FIB milling on the mechanical properties. Since micropillars are made by FIB milling, the damage layer at the free surface is always formed and would be expected to affect the mechanical properties at a sub-micron scale. Thus, pristine gold microparticles were produced by a solid-state dewetting technique, and the effects of FIB milling on both pristine and prestrained microparticles were examined via microcompression testing. These experiments revealed that FIB milling significantly reduces the strength of pristine microparticles, but does not alter that of prestrained microparticles. Thus, we confirmed that if there are pre-existing mobile-dislocations present in the crystal, FIB milling does not affect the mechanical properties. The second issue is the scaling law commonly used to describe the strength of micropillars as a function of sample size. For the scaling law, the power-law approximation has been widely used without understanding fundamental physics in it. Thus, we tried to analyze the power-law approximation in a quantitative manner with the well-known single arm source model. Material parameters, such as the friction stress, the anisotropic shear modulus, the magnitude of Burgers vector and the dislocation density, were explored to understand their effects on the scaling behavior. Considering these effects allows one to rationalize the observed material-dependent power-law exponents quantitatively. In another part of the dissertation, a
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Dislocation Dynamics and Plasticity

Dislocation Dynamics and Plasticity

These are the main subjects in Chaps. 5-7.

Author: Taira Suzuki

Publisher: Springer Science & Business Media

ISBN: 9783642757747

Category: Science

Page: 228

View: 717

In the 1950s the direct observation of dislocations became possible, stimulat ing the interest of many research workers in the dynamics of dislocations. This led to major contributions to the understanding of the plasticity of various crys talline materials. During this time the study of metals and alloys of fcc and hcp structures developed remarkably. In particular, the discovery of the so-called in ertial effect caused by the electron and phonon frictional forces greatly influenced the quantitative understanding of the strength of these metallic materials. Statis tical studies of dislocations moving through random arrays of point obstacles played an important role in the above advances. These topics are described in Chaps. 2-4. Metals and alloys with bcc structure have large Peierls forces compared to those with fcc structure. The reasons for the delay in studying substances with bcc structure were mostly difficulties connected with the purification techniques and with microscopic studies of the dislocation core. In the 1970s, these difficulties were largely overcome by developments in experimental techniques and computer physics. Studies of dislocations in ionic and covalent bonding materials with large Peierls forces provided infonnation about the core structures of dislocations and their electronic interactions with charged particles. These are the main subjects in Chaps. 5-7.
Categories: Science

Dynamic Models for Structural Plasticity

Dynamic Models for Structural Plasticity

Our topic is irreversible or plastic deformation of structural elements composed of relatively thin ductile materials.

Author: William J. Stronge

Publisher: Springer Science & Business Media

ISBN: 9781447103974

Category: Technology & Engineering

Page: 280

View: 918

Our topic is irreversible or plastic deformation of structural elements composed of relatively thin ductile materials. These deformations are commonly used in sheet metal forming operations to produce lightweight parts of any particular shape. In another context, this type of plastic deformation is described as impact damage in the case of structural components involved in collision. Here we are concerned with mechanics of both static and dynamic deformation processes. The purpose is to use typical material properties and structural characteristics to calculate the deformation for certain types of load; in particular to find the final deflection and shape of the deformed structure and to illustrate how the development of this final shape depends on the constitutive model used to represent the material behavior. The major issue to be addressed is which structural and constitutive properties are important for calculating response to either static or brief but intense dynamic loads. Furthermore, how do the results of various constitutive models compare with observed behavior.
Categories: Technology & Engineering

Shock Wave and High Strain Rate Phenomena in Materials

Shock Wave and High Strain Rate Phenomena in Materials

12 Short and Long Transients in Dynamic Plasticity of Metals , Modeling and Experimental Facts J.R. KLEPACZKO Laboratory of Physics and Mechanics of ...

Author: Meyers

Publisher: CRC Press

ISBN: 0824785797

Category: Technology & Engineering

Page: 1184

View: 194

These proceedings of EXPLOMET 90, the International Conference on the Materials Effects of Shock-Wave and High-Strain-Rate Phenomena, held August 1990, in La Jolla, California, represent a global and up-to-date appraisal of this field. Contributions (more than 100) deal with high-strain-rate deforma
Categories: Technology & Engineering

Dynamic Behavior of Materials Volume 1

Dynamic Behavior of Materials  Volume 1

Different strain rate sensitivities of metals have been examined through the ... Klepaczko JR (1992) Short and long transients in dynamic plasticity of ...

Author: Bo Song

Publisher: Springer Science & Business Media

ISBN: 9783319007717

Category: Technology & Engineering

Page: 496

View: 944

Dynamic Behavior of Materials, Volume 1: Proceedings of the 2013 Annual Conference on Experimental and Applied Mechanics, the first volume of eight from the Conference, brings together contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Experimental Mechanics, including papers on: General Dynamic Material Properties Novel Dynamic Testing Techniques Dynamic Fracture and Failure Novel Testing Techniques Dynamic Behavior of Geo-materials Dynamic Behavior of Biological and Biomimetic Materials Dynamic Behavior of Composites and Multifunctional Materials Dynamic Behavior of Low-Impedance materials Multi-scale Modeling of Dynamic Behavior of Materials Quantitative Visualization of Dynamic Behavior of Materials Shock/Blast Loading of Materials
Categories: Technology & Engineering

Dynamic Plasticity

Dynamic Plasticity

Experimental determination of the dynamic properties ofvarious materials The question of rate influence seems to be the central problem of dynamic ...

Author: N. Cristescu

Publisher: Elsevier

ISBN: 9780323163293

Category: Technology & Engineering

Page: 626

View: 202

Dynamic Plasticity discusses the problems encountered in the theory of dynamic deformation of plastic bodies. The book describes one-dimensional problems involving a single component of stress, particle velocity, and single spatial coordinate. The propagation of longitudinal elastic-plastic waves in thin rods or wires is a simple example of this problem of dynamic plasticity. Another one-dimensional problem, which has various possible transverse motions, is the dynamics of extensible strings. This problem is associated in calculations dealing with cables of suspension bridges, of elevator cables, of electric cables. The analogy with the mechanics of extensible strings can be extended to circular and rectangular membranes such as explained by Karunes and Onat. Karunes and Onat analyzed the propagation of transverse and longitudinal shock waves in such membranes using the Rakhmatulin theory for strings. The text also discusses axi-symmetrical problems and the problems of soil mechanics when applied to soft soils. The book can prove valuable to civil engineers, structural engineers, physicist, and students of mechanical engineering or industrial design.
Categories: Technology & Engineering

Dynamic Plasticity

Dynamic Plasticity

Discusses the field of dynamic plasticity. This book includes research chapters as well as an introduction to the elementary theory of plasticity.

Author: N. Cristescu

Publisher: World Scientific

ISBN: 9789812567475

Category: Technology & Engineering

Page: 468

View: 951

Discusses the field of dynamic plasticity. This book includes research chapters as well as an introduction to the elementary theory of plasticity. It covers such areas as a chapter on rocks and soils, the various developments in research on rate type, and problems concerning non-homogenous Bingham fluids, such as flow along an inclined slope.
Categories: Technology & Engineering

Handbook of Materials Behavior Models

Handbook of Materials Behavior Models

J. Materials Sri. 31: 6085. 8. Klepaczko, J. R. (1991). Physical-state variables: The key to constitutive modeling in dynamic plasticity.

Author: Jean Lemaître

Publisher: Academic Press

ISBN: 9780124433410

Category:

Page: 381

View: 451

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Metal Plasticity and Fatigue at High Temperature

Metal Plasticity and Fatigue at High Temperature

Johnson, G.R.; Cook, W.H. Fracture characteristics of three metals ... [CrossRef] Klepaczko, J.R. Constitutive modeling in dynamic plasticity based on ...

Author: Denis Benasciutti

Publisher: MDPI

ISBN: 9783039287703

Category: Technology & Engineering

Page: 220

View: 414

In several industrial fields (such as automotive, steelmaking, aerospace, and fire protection systems) metals need to withstand a combination of cyclic loadings and high temperatures. In this condition, they usually exhibit an amount—more or less pronounced—of plastic deformation, often accompanied by creep or stress-relaxation phenomena. Plastic deformation under the action of cyclic loadings may cause fatigue cracks to appear, eventually leading to failures after a few cycles. In estimating the material strength under such loading conditions, the high-temperature material behavior needs to be considered against cyclic loading and creep, the experimental strength to isothermal/non-isothermal cyclic loadings and, not least of all, the choice and experimental calibration of numerical material models and the selection of the most comprehensive design approach. This book is a series of recent scientific contributions addressing several topics in the field of experimental characterization and physical-based modeling of material behavior and design methods against high-temperature loadings, with emphasis on the correlation between microstructure and strength. Several material types are considered, from stainless steel, aluminum alloys, Ni-based superalloys, spheroidal graphite iron, and copper alloys. The quality of scientific contributions in this book can assist scholars and scientists with their research in the field of metal plasticity, creep, and low-cycle fatigue.
Categories: Technology & Engineering

Advances in Plasticity 1989

Advances in Plasticity 1989

Plasticity is now an established area of study within materials science and engineering mechanics.

Author: Akhtar S. Khan

Publisher: Elsevier

ISBN: 9781483287287

Category: Technology & Engineering

Page: 763

View: 471

Plasticity is now an established area of study within materials science and engineering mechanics. The proceedings of the Second International Symposium on Plasticity and its Current Applications brings together papers on all current areas of research into the plastic behaviour of solids. The main emphasis is on dynamic plasticity and study of deformation at crystal level but there are also papers on plasticity in particular materials such as superalloys and metal-matrix composites, the mechanics of damage, and the applications of plastic theory in metal-forming processes.
Categories: Technology & Engineering

The Physics of Large Deformation of Crystalline Solids

The Physics of Large Deformation of Crystalline Solids

The dynamic plasticity of metals at high strain rates: An experimental generalization. Colloquium on Behavior of Materials under Dynamic Loading.

Author: James F. Bell

Publisher: Springer Science & Business Media

ISBN: 9783642884405

Category: Science

Page: 254

View: 367

Historically, a major problem for the study of the large deformation of crystalline solids has been the apparent lack of unity in experimentally determined stress-strain functions. The writer's discovery in 1949 of the unexpectedly high velocity of incremental loading waves in pre-stressed large deformation fields emphasized to him the pressing need for the independent, systematic experimental study of the subject, to provide a firm foundation upon which physically plausible theories for the finite deformation of crystalline solids could be constructed. Such a study undertaken by the writer at that time and continued uninterruptedly to the present, led in 1956 to the development of the diffraction grating experiment which permitted, for the first time, the optically accurate determination of the strain-time detail of non-linear finite amplitude wave fronts propagating into crystalline solids whose prior history was precisely known. These experimental diffraction grating studies during the past decade have led to the discovery that the uniaxial stress-strain functions of 27 crystalline solids are unified in a single, generalized stress-strain function which is described, much of it hitherto unpublished, in the present monograph. The detailed study of over 2,000 polycrystal and single crystal uni axial stress experiments in 27 crystalline solids, in terms of the variation of a large number of pertinent parameters, has provided new unified pat terns of understanding which, it is hoped, will be of interest and value to theorists and experimentalists alike.
Categories: Science

Cold Gas Dynamic Spray

Cold Gas Dynamic Spray

Solid state spray forming of aluminum near-net shapes, JOM, 8, 31–33. Gao C.Y., Zhang L.C. (2010). A constitutive model for dynamic plasticity of FCC metals ...

Author: Roman Gr. Maev

Publisher: CRC Press

ISBN: 9781466584433

Category: Technology & Engineering

Page: 334

View: 448

Your Guide to Advanced Cold Spray Technology Cold Gas Dynamic Spray centers on cold gas dynamic spray (or cold spray—CS) technology, one of the most versatile thermal spray coating methods in materials engineering, and effectively describes and analyzes the main trends and developments behind the spray (coating) techniques. The book combines theory with practice to enable the reader to deeper understand the CS coatings as well as their structures and properties, and describes the state of the art in CS technology with an emphasis on all major components of the cold spray process. This book begins with an introduction to CS spray and goes on to thoroughly explain the process. It describes the different powder synthesis methods and equipment currently used, and defines the CS coating microstructure, characterization methods, and properties of CS coatings. The authors present a comprehensive approach that highlights grit blasting and cold spraying as well as the hybrid CS-sintering technology that offers integrity of microstructure, compositional homogeneity, and mechanical property levels equal to (and frequently better than) those of the wrought counterpart. The book largely covers the basic principles of CS technology and also includes: A brief survey of thermal spray methods The basic principles of plasticity theory A description of the CS equipment, the nozzle design, and the geometry of a CS gun Coverage of the microstructural and mechanical properties of CS metals and alloys A detailed analysis of aircraft component repair using GS An overview of the economic aspects of CS applications. Cold Gas Dynamic Spray explains how cold gas dynamic spray works and what it can do, and is intended for engineering professionals working with sprays and coatings in the industry as well as graduate student specializing in material science, mechanical, automotive, aerospace, and chemical engineering.
Categories: Technology & Engineering