effect of grain anisotrophy on limit strains in biaxial stretching.

by Pedro Manuel Brandao Rodrigues

Publisher: Universityof Birmingham in Birmingham

Written in English
Published: Downloads: 852
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Thesis (Ph.D) - University of Birmingham, Dept of Industrial Metallurgy.

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Open LibraryOL13738064M

Keywords AI-Cu-Mg-Mn alloy sheet, biaxial stretching, formability, forming limit strain, grain size, temper effects, tensile elongation. 1. Introduction ALLOY AA (nominally AICu-I.5MgMn) normally is used in the solution heat treated and aged T temper. However, fabricated sheet parts often are formed in the softer, fully annealed (O. including strain hardening exponent and anisotropy coefficients [], strain rate [], temperature [24], grain size and microstructure [], sheet thickness [27], strain path changes [], and heat treatment [30]. In recent years many experimental techniques have been developed to investigate the FLDs from different aspects [].   A homogeneous anisotropic biaxial strain field of 14% in the primary direction and % in the secondary direction was applied to these substrates, where the primary direction of stretch was oriented either parallel or perpendicular to the longitudinal axis of the aligned cell culture. at uniaxial tension. At plane strain, the R-value has little or no influence on the limit or fracture strain. A direct determination of the effect of R-value on the biaxial stretch forming characteristics of Ti sheet is precluded by the intervention of fracture prior to localized necking when the.

grain sized metals because each grain tends to deform independently use finer grained metals. • Mechanical fibering has little effect on formability. • Crystallographic fibering or preferred orientation may have a large effect. Ex: when bend line is parallel to the rolling direction, or earing in deep drawn cup due to anisotropic properties. The experimental data to which we applied this strain energy function included: radial and axial confined compression6, radial tension5, circumferential tension3, axial tension2, shear with compressive and tensile preloads4,7 and biaxial tension1. We limited the biaxial data to the axial stress response with circumferential strain held at 0%. The effect of the shape of the yield locus on the limit strains has been analyzed in detail by Barlat and Lian (). As we have emphasized in Banabic (), a lot of new yield criteria have been developed during the last decade. Many of those criteria have been already implemented in the computational models of the limit strains, in order to. Anisotropy Effects in the Forming of Aluminum Sheet S. J. Murtha, J. M. Story, G. W. Jarvis, and H. R. Zonker The Effect of Normal Anisotropy on Strength in Plane Strain and Pure Shear (from [3]) GA A]/ ~p'~p ^ ^ 7 ^ 7 ^ particularly in biaxial stretching.

iv geometry had an effect on formability. Moreover, weld position changed the formability of the welded blanks which was reflected in the limiting dome heights and the strain distribution profiles. Investigations of Residual Stresses and Mechanical Properties of Single Crystal Niobium for SRF Cavities Thomas Gnäupel-Herold1, Ganapati Rao Myneni2, Richard E. Ricker3 1National Institute of Standards and Technology, Center for Neutron Research, Bureau Dr., Gaithersburg, MD , USA and University of Maryland, Dept. of Materials Science and. the forming-limit diagram. Although the major strain is always positive (stretching), the minor strain may be either positive or negative or zero Dr. M. Medraj Mech. Eng. Dept. - Concordia UniversityMech / lecture 9/19 Forming-limit Diagrams (FLD) • More a research/development tool than a practical (quick) test • Time consuming to.   The limit strains in the plane strain condition are lower than in the limit strains in biaxial tension and drawing for all the heats. The pattern of the FLDs in the biaxial tension zone is largely dependent on the n value and the slope of the FLDs on the left-hand side (tension-compression) is influenced by r ̄ value

effect of grain anisotrophy on limit strains in biaxial stretching. by Pedro Manuel Brandao Rodrigues Download PDF EPUB FB2

With sheet thickness,t o, in the range to mm, it was found that limit strains in biaxial stretching decreased with decreasingt o /d o, whered o is average grain diameter. It was concluded that, when t o /d o was less than ab plastic anistropy of individual grains of the primary phase was the dominant source of the strain inhomogeneities which developed to cause eventual Cited by: Effects of grain anisotropy on limit strains in biaxial stretching: part ii.

sheets of cubic metals and alloys with well-developed preferred orientations. effect of grain anisotrophy on limit strains in biaxial stretching. book orientations do not provide a sufficient basis for prediction of the effects of preferred orientation on limit strains in biaxial by: With sheet thickness, t o, in the range to mm, it was found that limit strains in biaxial stretching decreased with decreasing t o /d o, where d o is average grain diameter.

It was concluded that, when t o /d o was less than ab plastic anistropy of individual grains of the primary phase was the dominant source of the strain inhomogeneities which developed to cause eventual necking by:   Influences of preferred orientation on the processes of strain localization which lead to necking failure in biaxial stretching have been investigated in sheets of copper, aluminium and low-carbon steels.

With copper having a volume fraction of {}() oriented grains, groove formation appeared to be essentially in accord with the predictions of bifurcation by: The effect of grain anisotropy on limit strains in biaxial stretching Author: Rodrigues, P.

ISNI: X Awarding Body: University of Birmingham Current Institution: University of Birmingham Date of Award: Availability of Full Text. The effect of grain anisotropy on limit strains in biaxial stretching. By P Rodrigues. Abstract. SIGLEAvailable from British Library Document Supply Centre- DSC:D/81 / BLDSC - British Library Document Supply CentreGBUnited Kingdo Topics: - Physics, general.

Biaxial Geogrids Biaxial geogrids exhibit significant stiffness and strength in two orthogonal directions. In these mate-rials, the bars and junctions provide geometrical sta-bility during transport and installation and almost al-ways provide interlock with the soil in which they are placed.

Anisotropic Biaxial Geogrids. With sheet thickness,t o, in the range to mm, it was found that limit strains in biaxial stretching decreased with decreasingt o/do, whered o is average grain diameter.

The limit strains of dual-phase steels DP and were evaluated in this work with a localization model formulated in plane-stress conditions using elasto-plastic constitutive equations. In this model, a geometrical imperfection parameter is defined from the sheet nominal thickness, initial ferrite grain size and average surface roughness.

forming limit, strain hardening, anisotropy, material inhomogeneity, surface roughness. INTRODUCTION. To determine the amount of deformation a material can withstand prior to necking failure the concept of forming limit diagram (FLC) was introduced. There exist a great variety of methods for calculating the FLD for sheet materials forming.

To establish the effect of grain size on the plastic instability, the material is assumed to be initially isotropic and obeys the power law work-hardening behaviour, given as (2) σ ¯ = C (ε 0 + ε ¯) n where σ ¯ is the effective stress, ε ¯ the effective strain, ɛ 0 the cold working strain, and C is the strength constant of the material.

The levels of the FLCs in plane strain (p-0) and in biaxial stretching (p > 0) decrease with increase in the grain diameter: the latter increase has caused an evident increase of the n-value, which in turn should have caused an increase in the level of the limit strains.

The predicted limit strains with the consideration of crystal rotation are found to be higher for the orientation {} and {} and the aluminium sheet. Whereas much lower predicted limit strains are observed for the {}. No simple trend of the effect of grain rotation on limit strain can be observed.

In fact, grain. anisotropy, strongly affects formability. In this research, we examine the limit-strain values in the plane-strain stretching mode, in terms of the evolution and stability of crystallographic orientations.

The effect that geometric or textural hardening has on the macroscopic response is also quantified. D.V.

Wilson's 24 research works with citations and reads, including: Internal elastic strains in an IF steel following changes in strain path. Such biaxial stretching limits are very sensitive to inhomogeneity with length scales greater than about half the sheet thickness, and significant factors in that inhomogeneity are the materials grain size and the spatial segregation of texture.

In this material, it appears that colonies of cube textured grains have an effect on the limit strains. hardening exponent (n), strain rate sensitivity parameter (m), Anisotropy parameter (r), grain size as well as strain path. Since the actual strain path in the effect of uniaxial and biaxial prestraining on the formabiiity of the low carbon Marciniak, Z., & kuczynski, K.

Limit strain in the processes of of stretch - forming sheet metal. This paper discusses the forming limit strains acquired from two testing methods: (a) biaxial tests and (b) dome tests.

Experiments were performed on AA annealed material to measure the limit strain in various deformation modes from uniaxial to equibiaxial strain mode. non balanced biaxial stretching paths.

Higher formability is found for {} texture component. produced by a combination of rolling reductions and annealing, suffer anisotropic effects on their properties.

They are caused by either: crystallographic anisotropy produced by sheet and the limit strain values, we analyzed the. Wilson DV, Roberts WT, Rodrigues PMB () Effect of grain anisotropy on limit strains in biaxial stretching: part i. influence of sheet thickness and grain size in weakly textured sheets.

Metall Trans A – doi: /BF @article{osti_, title = {Effect of grain shape and texture on equi-biaxial creep of stress relieved and recrystallized Zircaloy-4}, author = {Murty, K L and Tanikella, B V and Earthman, J C}, abstractNote = {Zirconium alloys are extensively used in various types of fission reactors both light and heavy water types for different applications, examples being thin-walled tubing to clad.

alloy aluminum analysis anisotropic Applications approach assumed band behavior biaxial stretching buckling bulk calculated cavities comparison component computed considered constant corresponding criterion critical crystallographic curvature curves damage defect deformation depends determined direction distribution effect equation equi-biaxial.

friction, biaxial strain limits, and springback) during biaxial stretching, these materials can be more readily utilized for complex stamped components.

Along these lines, the free surface roughening of a model aluminum alloy in the 5XXX series was studied as a function of biaxial straining using the modified Marciniak in-plane stretching test. Conversely, in the biaxial stretching domain the limit strains are strongly affected when the plastic anisotropy coefficient r 45 is > whereas the same FLC's are obtained for the isotropic (r 45 = ) and r strain (c) Plane strain (d) Equi-biaxial stretching 1.

Predicted transformation kinetics and ultimate ductility (indicated by x) under different loading conditions are in qualitatively good agreements with experimental measurements.

Prediction Plotted at %. It is known that the crystallographic texture affects very much the mechanical properties of sheet metals. In this paper, rolled aluminum alloy sheets are considered as target materials. Typical texture components usually observed in rolled aluminum alloy sheets are the deformation textures of Cu, Brass and S, and the recrystallization textures of Cube and Goss.

Effects of local grain misorientation and β-Sn elastic anisotropy on whisker and hillock formation - Volume 28 Issue 5 - Pylin Sarobol, Wei-Hsun Chen, Aaron E.

plays a significant role in forming limit strains. All of the above-mentioned studies are based on the Taylor model, which assumes the local strain response of individual grains is equal to the macroscopic strain regardless of grain orientation [10].

Signorelli et al. Biaxial stretching is performed in dies giving different degrees of stress biaxiality.

Resulting effective stresses and plastic strains are estimated according to the original Hill’s theory in the two situations where planar anisotropy is either neglected or taken into consideration.

Forming limit diagrams were plotted using strain localization and fracture criteria from experimental and simulated strain path curves. Effect of plastic anisotropy on crack propagation direction was studied using finite element method, and it has been found that the direction of crack propagation was strongly dependent on plastic anisotropy.

strain localization, strain hardening, and surface roughness. Similar observations were made by Jain et al. [9] who investigated the relation between strain hardening, grain size, and sur-face roughening with respect to biaxial tensile limit strains of aluminum.The effects of anisotropy and strain hardening on material formability were also investigated.

On the other hand, a practical approach was implemented for experimental determination of FLD and several theoretical models for prediction of forming limit diagrams for mm thick Ti-6Al-4V titanium sheet alloy subjected to linear strain paths were.

This article addresses a theoretical analysis of the 'modified maximum force criterion' (MMFC) introduced by Hora et al ( A prediction method for ductile sheet metal failure i.