Hybrid Bishop-Hill Model for Elastic-Yield Limited Design With Non-orthorhombic Polycrystalline Metals

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Ribeka Takahashi ◽  
Dikshya Prasai ◽  
Brent L. Adams ◽  
Christopher A. Mattson
Keyword(s):  
Stress State ◽  
Yield Surface ◽  
Crystallographic Texture ◽  
Thin Sheets ◽  
Hill Model ◽  
Design Problems ◽  
Fcc Metals ◽  
Polycrystalline Metals ◽  
Principal Directions ◽  
Maximum Work

A method is presented for adapting the classical Bishop-Hill model to the requirements of elastic/yield-limited design in metals of arbitrary crystallographic texture. The proposed Hybrid Bishop-Hill (HBH) model, which will be applied to ductile FCC metals, retains the “stress corners” of the polyhedral Bishop-Hill yield surface. However, it replaces the ‘maximum work criterion’ with a criterion that maximizes the projection of the applicable local corner stress state onto the macroscopic stress state. This compromise leads to a model that is much more accessible to yield-limited design problems. Demonstration of performance for the HBH model is presented for an extensive database for oxygen free electronic copper. The design problem considered is a hole-in-a-plate configuration of thin sheets loaded in uniaxial tension in arbitrary directions relative to the principal directions of material orthorhombicity. Results obtained demonstrate that HBH-based elastic/yield limited design is capable of predicting complex and highly nonintuitive behaviors, even within standard problems.

scholarly journals Programming curvilinear paths of flat inflatables

2019 ◽  
Vol 116 (34) ◽  
pp. 16692-16696 ◽  
Author(s):  
Emmanuel Siéfert ◽  
Etienne Reyssat ◽  
José Bico ◽  
Benoît Roman
Keyword(s):  
Inverse Problem ◽  
Stress State ◽  
Internal Pressure ◽  
Minimal Model ◽  
Thin Sheets ◽  
Inflatable Structures ◽  
Deployable Structures ◽  
Application Potential ◽  
Numerical Tool ◽  
Target Path

Inflatable structures offer a path for light deployable structures in medicine, architecture, and aerospace. In this study, we address the challenge of programming the shape of thin sheets of high-stretching modulus cut and sealed along their edges. Internal pressure induces the inflation of the structure into a deployed shape that maximizes its volume. We focus on the shape and nonlinear mechanics of inflated rings and more generally, of any sealed curvilinear path. We rationalize the stress state of the sheet and infer the counterintuitive increase of curvature observed on inflation. In addition to the change of curvature, wrinkles patterns are observed in the region under compression in agreement with our minimal model. We finally develop a simple numerical tool to solve the inverse problem of programming any 2-dimensional (2D) curve on inflation and illustrate the application potential by moving an object along an intricate target path with a simple pressure input.

The Effect of Stress-State on the Large Strain Inelastic Deformation Behavior of 304L Stainless Steel

1996 ◽  
Vol 118 (1) ◽  
pp. 28-36 ◽  
Author(s):  
M. P. Miller ◽  
D. L. McDowell
Keyword(s):  
Stainless Steel ◽  
Stress State ◽  
Strain Hardening ◽  
Crystallographic Texture ◽  
Inelastic Deformation ◽  
Large Strain ◽  
Relative Effect ◽  
Material Behavior ◽  
304L Stainless Steel ◽  
Inelastic Material

In metals, large strain inelastic deformation processes such as the formation of a preferred crystallographic orientation (crystallographic texture) and strain hardening processes such as the formation and evolution of dislocation substructures depend on stress-state. Much of the current large strain research has focused on texture. Crystallographic texture development and strainhardening processes each contribute to the overall material behavior, and a complete description of large strain inelastic material response should reflect both. An investigation of the large strain behavior of 304L stainless steel (SS 304L) subjected to compression, torsion, and sequences of compression followed by torsion and torsion followed by tension is reported. This paper focuses on the stress-state dependence of strain-hardening processes as well as the relative effect such processes have on the overall material behavior. To characterize these processes, transmission electron microscopy (TEM) as well as magnetization investigations were conducted at different strain levels and under different deformation modes. The γ → α′ martensitic transformation which occurs in this material was found to be related to both the strain level and stress state. Dislocation substructures in the form of Taylor lattices, dense dislocation walls, and microbands were also present. The ramifications of using a thin-walled tubular torsion specimen were also explored.

Numerical Study on the Influence of Crystallographic Texture and Grain Shape on the Yield Surface of Textured Aluminum Sheet Material

2014 ◽  
Vol 794-796 ◽  
pp. 584-589 ◽  
Author(s):  
Afaf Saai ◽  
Odd Sture Hopperstad ◽  
Stéphane Dumoulin ◽  
Laurent Tabourot
Keyword(s):  
Yield Surface ◽  
Crystallographic Texture ◽  
Grain Shape ◽  
Numerical Study ◽  
Sheet Material ◽  
Grain Morphology ◽  
Yield Function ◽  
Aluminum Sheet ◽  
Taylor Model ◽  
Yield Surfaces

The paper investigates by numerical modeling the effects of crystallographic texture and grain shape on the shape of the yield surface of aluminum sheet material at small strains. Different representative volume elements (RVEs) of the material are considered. Plane stress state is assumed in the sheet. A rate-dependent model of crystal plasticity (CP) is used in combination with either the full-constraint (FC) Taylor model or the finite element method (FEM) to compute the volume averaged stress of the material. The effect of different crystallographic textures observed in aluminum alloys on the shape of the yield surface is firstly investigated. An analytical yield function is used to generate yield surfaces for the different crystallographic textures. The deviation between the stress states at yielding computed by FC-Taylor model and the analytical yield surface is used to evaluate the capability of the yield function to fit the anisotropic yield surfaces representing different strong crystallographic textures. Two different shapes of the grains are introduced in the RVEs of CP-FEM in order to study the effect of the grain morphology. Small effects of grain shape are found at small strain compared with the marked influence of crystallographic texture.

Polycrystalline plasticity and the evolution of crystallographic texture in FCC metals

1992 ◽  
Vol 341 (1662) ◽  
pp. 443-477 ◽  
Keyword(s):  
Finite Element ◽  
Crystallographic Texture ◽  
Single Phase ◽  
Type Model ◽  
Strain Response ◽  
Stress Strain ◽  
Fcc Metals ◽  
First Order ◽  
Finite Element Calculations ◽  
Simple Compression

A Taylor-type model for large deformation polycrystalline plasticity is formulated and evaluated by comparing the predictions for the evolution of crystallographic texture and the stress-strain response in simple compression and tension, plane strain compression, and simple shear of initially ‘isotropic’ OFHC copper against ( a ) corresponding experiments, and ( b ) finite element simulations of these experiments using a multitude of single crystals with accounting for the satisfaction of both compatibility and equilibrium. Our experiments and calculations show that the Taylor-type model is in reasonable first-order agreement with the experiments for the evolution of texture and the overall stress-strain response of single-phase copper. The results of the finite element calculations are in much better agreement with experiments, but at a substantially higher computational expense.

The Explanation of Yield Surface Rotation of Sands by Principle of Thermodynamics with Internal Variables

2014 ◽  
Vol 580-583 ◽  
pp. 308-311
Author(s):  
Jing Yu Chen ◽  
Ying Hai
Keyword(s):  
Stress State ◽  
Yield Surface ◽  
Triaxial Compression ◽  
Constitutive Modelling ◽  
Saturated Soils ◽  
Internal Variables ◽  
Compression Stress ◽  
Surface Rotation ◽  
Saturated Sands ◽  
Yield Surfaces

<p class="p18">Using constitutive modelling principle of thermodynamics with internal variables, the yield surfaces rotation of saturated sands subjected triaxial compression stress state are justified and explained. The explanation for the yield surfaces rotation of saturated sands prove the correctness and feasibility for the principle of thermodynamics with internal variables to construct elastoplastic constitutive relation of saturated soils.</p>

Influence of crystallographic texture on the microstructure, tensile properties and residual stress state of laser-welded titanium joints

2016 ◽  
Vol 101 ◽  
pp. 137-145 ◽  
Author(s):  
Emad Maawad ◽  
Weimin Gan ◽  
Michael Hofmann ◽  
Volker Ventzke ◽  
Stefan Riekehr ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Tensile Properties ◽  
Crystallographic Texture ◽  
Residual Stress State

Initiation of static instability in the submarine Nerlerk berm

1993 ◽  
Vol 30 (6) ◽  
pp. 895-904 ◽  
Author(s):  
Poul V. Lade
Keyword(s):  
Shear Strength ◽  
Stress State ◽  
Yield Surface ◽  
Failure Surface ◽  
Triaxial Tests ◽  
Analysis Method ◽  
Trigger Mechanism ◽  
Plastic Properties ◽  
Static Instability ◽  
Undrained Conditions

According to stability postulates by other authors, soils that exhibit nonassociated flow may become unstable when exposed to certain stress paths inside the failure surface. Several series of conventional triaxial tests on fully saturated specimens have been performed to study the regions of stable and unstable behavior. For saturated specimens that tend to compress, undrained conditions lead to effective stress paths directed within the region of potential instability, and instability is observed, provided the yield surface opens up in the outward direction of the hydrostatic axis. Thus, instability occurs inside the failure surface. Instability is not synonymous with failure, although both lead to catastrophic events. The location of the region of potential instability and its determination are discussed. The submarine Nerlerk berm, which suffered six slides during its construction, is analyzed using a newly developed method of instability analysis. It is shown that conventional slope stability methods do not capture the mechanics of instability and subsequent liquefaction. The proposed analysis method is based on the location of the region of potential instability and the stress state in the ground. In addition, a trigger mechanism is required to initiate the instability. These topics are discussed with reference to the slides in the Nerlerk berm. Key words : instability, nonassociated flow, plastic properties, sand, shear strength, submarine slope.

Texture Evolution in Commercially Pure Al during Equal Channel Angular Extrusion (ECAE) as a Function of Processing Routes

2005 ◽  
Vol 105 ◽  
pp. 357-362 ◽  
Author(s):  
Satyam Suwas ◽  
László S. Tóth ◽  
Jean-Jacques Fundenberger ◽  
André Eberhardt
Keyword(s):  
Crystallographic Texture ◽  
Equal Channel Angular Extrusion ◽  
Texture Evolution ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Fcc Metals ◽  
Commercially Pure ◽  
Angular Extrusion ◽  
Deformation Modes

FCC metals with different stacking fault energy (SFE), namely Al, Cu and Ag have been investigated for the evolution of crystallographic texture during ECAE deformation using Route A. Different materials with different SFE result in their characteristic textures. The results have been analysed on the basis of microstructural features and related established concepts on texture evolution in FCC metals during other deformation modes.

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