An effective Schmid factor in consideration of combined normal and shear stresses for slip/twin variant selection of Mg-3Al-1Zn alloy

2019 ◽  
Vol 167 ◽  
pp. 51-55 ◽  
Author(s):  
Shuai-Feng Chen ◽  
Hong-Wu Song ◽  
Shi-Hong Zhang ◽  
Ming Cheng ◽  
Ce Zheng ◽  
...  
Keyword(s):  
Shear Stresses ◽  
Variant Selection ◽  
Twin Variant ◽  
Schmid Factor ◽  
Selection Of ◽  
Normal And Shear Stresses

Multiple twinning in pure hexagonal close-packed titanium

2013 ◽  
Vol 46 (5) ◽  
pp. 1397-1406 ◽  
Author(s):  
Lei Bao ◽  
Yudong Zhang ◽  
Christophe Schuman ◽  
Jean-Sébastien Lecomte ◽  
Marie-Jeanne Philippe ◽  
...  
Keyword(s):  
Pure Titanium ◽  
Variant Selection ◽  
Hexagonal Close Packed ◽  
Twin Variant ◽  
Commercial Pure Titanium ◽  
The Matrix ◽  
Schmid Factor ◽  
Sample Technique ◽  
Multiple Twinning ◽  
Selection Of

Commercial pure titanium (T40) was deformed in channel die compression by means of the split-sample technique in order to study multiple twinning. Particular attention was paid to the twin variant presentation and selection during multiple twinning. All possible misorientations, corresponding to the multiple twins arising from the combination of the {1 1 {\overline 2} 2} compression (C) twin, the {1 0 {\overline 1} 2} tension twin (T1) and the {1 1 {\overline 2} 1} tension twin (T2), were calculated with respect to the crystal basis of the matrix grain. All the multiple twin variants are partitioned into ten classes with the same crystallographically equivalent misorientation angle and axis. However, when the influence of twinning order is taken into account, the multiple twin variants are partitioned into 15 classes. Experimental results prove that the selection of twin variants (primary and secondary) is mainly governed by their macroscopic Schmid factor (SF). The normalized SF is more efficient at predicting variant selection. A twin formed in one grain can activate another twin in a neighbouring grain, provided that the angle between the two twinning planes does not exceed 20°.

Tribological Characteristics of Carbon/Epoxy Composites With Respect to Surface Groove Dimensions

2006 ◽  
Author(s):  
Hak Gu Lee ◽  
Seong Su Kim ◽  
Dai Gil Lee
Keyword(s):  
Epoxy Composite ◽  
Epoxy Composites ◽  
Tribological Characteristics ◽  
Shear Stresses ◽  
Optimum Selection ◽  
Grooved Surface ◽  
Ridge Width ◽  
Sliding Test ◽  
Selection Of ◽  
Normal And Shear Stresses

Grooves on the surface of carbon/epoxy composite bearings yield good tribological characteristics because wear debris generated on the sliding surface are removed efficiently through the grooves. However, the surface grooves increase normal and shear stresses in composite bearings, consequently, excessive area of the grooves increases wear of the carbon/epoxy composite bearings, which necessitates the optimum selection of groove dimensions on the surface of composite bearings. In this work, the friction and wear characteristics of carbon/epoxy composites with micro-grooves were investigated by dry sliding test with respect to groove width and ridge width. Through comparison between the flat surface and the grooved surface, proper widths of the groove and ridge of carbon/epoxy composite bearings were determined.

Loading Mode Dependence of {$$10\bar{1}2$$} Twin Variant Selection in a Rolled Mg-Al-Zn Alloy

2021 ◽  
Author(s):  
Longhui Mao ◽  
Chuming Liu ◽  
Yingchun Wan ◽  
Tao Chen ◽  
Shunong Jiang ◽  
...  
Keyword(s):  
Variant Selection ◽  
Twin Variant ◽  
Loading Mode ◽  
Zn Alloy

scholarly journals Strain Accommodations among Twin Variants in Ti and Mg

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 453
Author(s):  
Ping Zhou ◽  
Guo-Zhen Zhu
Keyword(s):  
Mechanical Property ◽  
Great Influence ◽  
Local Strain ◽  
Deformation Texture ◽  
Variant Selection ◽  
Slip Systems ◽  
Twinning Shear ◽  
Active Variant ◽  
Shed Light ◽  
Selection Of

The selection of twin variants has a great influence on deformation texture and mechanical property in hcp metals where slip systems are limited and twinning types are abundant during deformation. Local strain accommodations among twin variants are considered to shed light on variant selection rules in Ti and Mg alloys. Five kinds of strain accommodations are discussed in terms of different regions that are affected by the twinning shear of primary twin. These regions contain (I) the whole sample, (II) neighboring grain, (III) adjacent primary twin in neighboring grain, (IV) adjoining primary twin within the same parent grain, and (V) multi-generation of twinning inside the primary twin. For a potentially active variant, its operation needs not only relatively higher resolved shear stress but also easily accommodated strain by immediate vicinity. Many of the non-Schmid behaviors could be elucidated by local strain accommodations that variants with relatively higher SFs hard to be accommodated are absent, while those with relatively lower SFs but could be easily accommodated are present.

An Experimental Investigation of the Yield Loci of 1100-0 Aluminum, 70:30 Brass, and an Overaged 2024 Aluminum Alloy After Various Prestrains

1986 ◽  
Vol 108 (4) ◽  
pp. 313-320 ◽  
Author(s):  
D. E. Helling ◽  
A. K. Miller ◽  
M. G. Stout
Keyword(s):  
Aluminum Alloy ◽  
Small Strain ◽  
Yield Locus ◽  
Material Behavior ◽  
Shear Stresses ◽  
2024 Aluminum Alloy ◽  
Yield Loci ◽  
Aluminum Alloy 2024 ◽  
Von Mises ◽  
Normal And Shear Stresses

The multiaxial yield behaviors of 1100-0 aluminum, 70:30 brass, and an overaged 2024 aluminum alloy (2024-T7) have been investigated for a variety of prestress histories involving combinations of normal and shear stresses. Von Mises effective prestrains were in the range of 1.2–32%. Prestress paths were chosen in order to investigate the roles of prestress and prestrain direction on the nature of small-strain offset (ε = 5 × 10−6) yield loci. Particular attention was paid to the directionality, i.e., translation and distortion, of the yield locus. A key result, which was observed in all three materials, was that the final direction of the prestrain path strongly influences the distortions of the yield loci. Differences in the yield locus behavior of the three materials were also observed: brass and the 2024-T7 alloy showed more severe distortions of the yield locus and a longer memory of their entire prestrain history than the 1100-0 aluminum. In addition, more “kinematic” translation of the subsequent yield loci was observed in brass and 2024-T7 than in 1100-0 aluminum. The 2024-T7 differed from the other materials, showing a yield locus which decreased in size subsequent to plastic straining. Finally, the implications of these observations for the constitutive modeling of multiaxial material behavior are discussed.

Computer analysis of thin-walled concrete box beams

1989 ◽  
Vol 16 (6) ◽  
pp. 902-909 ◽  
Author(s):  
Shahbaz Mavaddat ◽  
M. Saeed Mirza
Keyword(s):  
Key Words ◽  
Computer Analysis ◽  
Shear Stresses ◽  
Shear Lag ◽  
Applied Loading ◽  
Box Beam ◽  
Box Beams ◽  
Three Stages ◽  
Thin Walled ◽  
Normal And Shear Stresses

Three computer programs, written in FORTRAN WATFIV, are developed to analyze straight, monolithically cast, symmetric concrete box beams with one, two, or three cells and side cantilevers over a simple span or over two spans with symmetric mid-span loadings. The analysis, based on Maisel's formulation, is performed in three stages. First, the structure is idealized as a beam and the normal and shear stresses are calculated using the simple bending theory and St-Venant's theory of torsion. The secondary stresses arising from torsional and distortional warping and shear lag are calculated in the second and third stages, respectively. The execution times on an AMDAHL 580 system are 0.02, 0.93, and 0.25 s for the three programs, respectively. The stresses arising in each stage of analysis are then superposed to determine the overall response of the box section to the applied loading. The results are compared with Maisel's hand calculations. Key words: bending, bimoment, box beam, computer analysis, FORTRAN, shear, shear lag, thin-walled section, torsion, torsional and distortional warping.

A Study of Twin Variant Selection and Twin Growth in Titanium

2011 ◽  
Vol 13 (10) ◽  
pp. 928-932 ◽  
Author(s):  
Lei Bao ◽  
Christophe Schuman ◽  
Jean-Sébastien Lecomte ◽  
Marie-Jeanne Philippe ◽  
Xiang Zhao ◽  
...  
Keyword(s):  
Variant Selection ◽  
Twin Variant ◽  
Twin Growth

Measurements in a Turbulent Boundary Layer Over a d-Type Surface Roughness

1975 ◽  
Vol 42 (3) ◽  
pp. 591-597 ◽  
Author(s):  
D. H. Wood ◽  
R. A. Antonia
Keyword(s):  
Boundary Layer ◽  
Surface Roughness ◽  
Turbulent Boundary Layer ◽  
Turbulent Energy ◽  
Shear Stresses ◽  
Normal Velocity ◽  
Mean Velocity ◽  
Outer Flow ◽  
Intensity Measurements ◽  
Normal And Shear Stresses

Mean velocity and turbulence intensity measurements have been made in a fully developed turbulent boundary layer over a d-type surface roughness. This roughness is characterised by regular two-dimensional elements of square cross section placed one element width apart, with the cavity flow between elements being essentially isolated from the outer flow. The measurements show that this boundary layer closely satisfies the requirement of exact self-preservation. Distribution across the layer of Reynolds normal and shear stresses are closely similar to those found over a smooth surface except for the region immediately above the grooves. This similarity extends to distributions of third and fourth-order moments of longitudinal and normal velocity fluctuations and also to the distribution of turbulent energy dissipation. The present results are compared with those obtained for a k-type or sand grained roughness.

Strain compatibility effect on the variant selection of connected twins in magnesium

2015 ◽  
Vol 76 ◽  
pp. 71-76 ◽  
Author(s):  
Changfa Guo ◽  
Renlong Xin ◽  
Jianbin Xu ◽  
Bo Song ◽  
Qing Liu
Keyword(s):  
Compatibility Effect ◽  
Variant Selection ◽  
Strain Compatibility ◽  
Selection Of
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