Strain ratio as the measure of plastic anisotropy

2001 ◽  
pp. 19-36
Author(s):  
Wojciech Truszkowski
Keyword(s):  
Plastic Anisotropy ◽  
Strain Ratio

scholarly journals Effects of Initial Precipitate on Shear Deformation during Asymmetric Rolling of Al-Mg-Si Alloy: Texture and Formability

2020 ◽  
Vol 58 (10) ◽  
pp. 703-714
Author(s):  
Wonkee Chae ◽  
Bong-Kyu Kim ◽  
Jongbeom Lee ◽  
Jun Hyun Han
Keyword(s):  
Shear Deformation ◽  
Room Temperature ◽  
Tensile Deformation ◽  
Texture Evolution ◽  
Plastic Anisotropy ◽  
Rolling Direction ◽  
Strain Ratio ◽  
Equivalent Strain ◽  
Asymmetric Rolling ◽  
Plastic Strain Ratio

Al-Mg-Si alloy was rolled asymmetrically at several temperatures to apply shear deformation, and the effects of the initial precipitate on shear deformation, texture evolution, formability, and plastic anisotropy were studied. Texture was analyzed using a EBSD, and the formability and plastic anisotropy of the specimen were evaluated using the value and value calculated from the plastic strain ratio (r-value) which was determined from the change in the length of the specimen during tensile deformation. Asymmetric rolling induces a larger equivalent strain than symmetric rolling, and the equivalent strain increases as the asymmetric rolling temperature increases. When a specimen with peak-aged initial precipitates was asymmetrically rolled, less shear deformation occurred at room temperature than in a solution-treated specimen without initial precipitates. In contrast, a larger shear deformation occurred at high temperatures (500°C). With asymmetric rolling at room temperature, the specimens without initial precipitates had higher formability and lower plasticity, while for asymmetric rolling at high temperature, the specimens with initial precipitates had higher formability and lower plastic anisotropy. This is due to the <111>//ND texture, such as {111}<110> and {111}<112> orientation that has similar and high r-values at 0°, 45°, and 90° to the rolling direction, developed by the shear deformation that occurred during asymmetric rolling.

Plastic Deformation of Anisotropic Tubes in Hydraulic Bulging

1978 ◽  
Vol 100 (4) ◽  
pp. 421-425 ◽  
Author(s):  
D. M. Woo ◽  
A. C. Lua
Keyword(s):  
Strain Distribution ◽  
Circumferential Strain ◽  
Plastic Anisotropy ◽  
Strain Ratio ◽  
Stress Strain ◽  
Thickness Strain ◽  
Process Comparison ◽  
Tension Tests ◽  
Anisotropy Effect ◽  
Hydraulic Bulging

The anisotropy of tubular material is assessed from the values of the width/thickness strain ratio determined in the tension tests. Applying Hill’s theory of plastic anisotropy, these values are incorporated in the expressions for determining the stress/strain characteristics for anisotropic material in the tension and bulge tests, and also in the theoretical analysis of the hydraulic bulging of anisotropic tubes. Experiments have been carried out on copper tubes. Taking into account the anisotropy effect, the stress/strain curves determined in the tension and bulge tests agree closely except at the low strain region. In the analysis of the bulging process, comparison is made between the theoretical and the experimental circumferential strain distribution. The results appear satisfactory.

scholarly journals A Theoretical Analysis of Equibiaxial Deformation Texture Under Non-prescribed Strain Path

1990 ◽  
Vol 13 (1) ◽  
pp. 31-40 ◽  
Author(s):  
W. B. Lee ◽  
K. C. Chan
Keyword(s):  
Grain Orientation ◽  
Strain Path ◽  
Plastic Anisotropy ◽  
Strain Ratio ◽  
Deformation Texture ◽  
Linear Strain ◽  
Current State ◽  
Grain Orientations ◽  
Strain Paths ◽  
The Stability

A model is presented to calculate the rotation path of crystals under equibiaxial tension when the strain ratio is fixed (prescribed strain path) or when the strain ratio is allowed to adjust itself according to the external constraint and the current state of the plastic anisotropy of the material (nonprescribed strain path). It is found that the stability of grain orientation is related to the curvature of the strain path. There is a difference in the predicted equibiaxial deformation texture for the two types of strain paths. Grain orientations which are unstable under a linear strain path may become stable under a non-linear or varying strain path.

ROLE OF SEMIQUANTITATIVE ELASTOGRAPHY BY STRAIN RATIO IN PREDICTING MALIGNANCY OF PANCREATIC MASSES

2018 ◽  
Author(s):  
D Vasile Balaban ◽  
C Marina ◽  
A Zoican ◽  
G Robu ◽  
I Enache ◽  
...  
Keyword(s):  
Strain Ratio ◽  
Pancreatic Masses ◽  
Semiquantitative Elastography

SANDVIK Ti-3Al-2.5V GRADE 9

Alloy Digest ◽  
1997 ◽  
Vol 46 (9) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Endurance Limit ◽  
Weight Ratio ◽  
High Strength ◽  
Strain Ratio ◽  
Bend Strength ◽  
Aerospace Applications ◽  
Excellent Corrosion Resistance ◽  
Titanium Aluminum ◽  
Fatigue Endurance

Abstract Sandvik Ti-3Al-2.5V Grade 9 titanium-aluminum alloy offers excellent corrosion resistance, especially to chloride media, and has a high strength-to-weight ratio, which is especially suitable for use in aerospace applications. Tubing can be produced having a CSR (contractile strain ratio) that enhances the fatigue endurance limit. This datasheet provides information on composition, physical properties, elasticity, tensile properties, and bend strength as well as fatigue. It also includes information on corrosion resistance as well as forming, machining, and joining. Filing Code: TI-109. Producer or source: Sandvik.

scholarly journals Results of liver and spleen endoscopic ultrasonographic elastography predict portal hypertension secondary to chronic liver disease

2020 ◽  
Vol 08 (11) ◽  
pp. E1623-E1632
Author(s):  
Carlos Robles-Medranda ◽  
Roberto Oleas ◽  
Miguel Puga-Tejada ◽  
Manuel Valero ◽  
Raquel Del Valle ◽  
...  
Keyword(s):  
Liver Cirrhosis ◽  
Portal Hypertension ◽  
Liver Disease ◽  
Chronic Liver Disease ◽  
Predictive Value ◽  
Strain Ratio ◽  
Chronic Liver ◽  
Spleen Stiffness ◽  
Eus Elastography ◽  
Sensitivity Specificity

Abstract Background and study aims Assessment of endoscopic ultrasonography (EUS)-elastography of the liver and spleen may identify patients with portal hypertension secondary to chronic liver disease. We aimed to evaluate use of EUS-elastography of the liver and spleen in identification of portal hypertension in patients with chronic liver disease. Patients and methods This was a single-center, diagnostic cohort study. Consecutive patients with liver cirrhosis and portal hypertension underwent EUS-elastography of the liver and spleen. Patients without a history of liver disease were enrolled as controls. The primary outcome was diagnostic yield of liver and spleen stiffness measurement via EUS-elastography in prediction of portal hypertension secondary to chronic liver cirrhosis. Cutoff values were defined through Youden’s index. Overall accuracy was calculated for parameters with an area under the receiver operating characteristic (AUROC) curve ≥ 80 %. Results Among the 61 patients included, 32 had cirrhosis of the liver. Liver and spleen stiffness was measured by the strain ratio and strain histogram, with sensitivity/(1 − specificity) AUROC values ≥ 80 %. For identification of patients with cirrhosis and portal hypertension, the liver strain ratio (SR) had a sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 84.3 %, 82.8 %, 84.4 %, and 82.8 %, respectively; the liver strain histogram (SH) had values of 87.5 %, 69.0 %, 75.7 %, and 83.3 %, respectively. EUS elastography of the spleen via the SR reached a sensitivity, specificity, PPV, and NPV of 87.5 %, 69.0 %, 75.7 %, and 83.3 %, respectively, whereas the values of SH were 56.3 %, 89.7 %, 85.7 %, and 65.0 %, respectively. Conclusion Endoscopic ultrasonographic elastography of the liver and spleen is useful for diagnosis of portal hypertension in patients with cirrhosis.

Cervical elastography strain ratio and strain pattern for the prediction of a successful induction of labour

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Marlit Karen Strobel ◽  
Maria Eveslage ◽  
Helen Ann Köster ◽  
Mareike Möllers ◽  
Janina Braun ◽  
...  
Keyword(s):  
Strain Ratio ◽  
Cervical Length ◽  
Transformation Process ◽  
Induction Of Labour ◽  
Bishop Score ◽  
Cervical Tissue ◽  
Strain Pattern ◽  
Successful Induction ◽  
Study Population ◽  
First Time

AbstractObjectivesThe aim of this study was to introduce cervical strain elastography to objectively assess the cervical tissue transformation process during induction of labour (IOL) and to evaluate the potential of cervical elastography as a predictor of successful IOL.MethodsA total of 41 patients with full-term pregnancies elected for an IOL were included. Vaginal ultrasound with measurement of cervical length and elastography and assessment of the Bishop Score were performed before and 3 h after IOL. The measured parameters were correlated to the outcome of IOL and the time until delivery.ResultsWe observed an association between the strain pattern and the value of the strain ratio 3 h after IOL and a successful IOL (p=0.0343 and p=0.0342, respectively) which can be well demonstrated by the results after 48 h. In our study population the cervical length and the Bishop Score did not prove to be relevant parameters for the prediction of a successful IOL.ConclusionsWe demonstrated for the first time that the cervical elastography pattern after the first prostaglandine application can help predict the outcome of IOL.

scholarly journals TIRADS, SRE and SWE in INDETERMINATE thyroid nodule characterization: Which has better diagnostic performance?

2021 ◽  
Author(s):  
Ilaria Celletti ◽  
Daniele Fresilli ◽  
Corrado De Vito ◽  
Marco Bononi ◽  
Sara Cardaccio ◽  
...  
Keyword(s):  
Thyroid Nodule ◽  
Preoperative Staging ◽  
Shear Wave Elastography ◽  
Roc Curves ◽  
Strain Ratio ◽  
Multicenter Studies ◽  
Increased Sensitivity ◽  
Bonferroni Test ◽  
Indeterminate Cytology ◽  
Sensitivity Specificity

Abstract Purpose To assess Strain Ratio (SRE) and Shear Wave Elastography (SWE) accuracy alone and with TIRADS classification, for the risk stratification of indeterminate thyroid nodules. Materials and methods 128 Patients with 128 indeterminate nodules candidates for thyroidectomy underwent preoperative staging neck ultrasound and were classified according to K-TIRADS score. After TIRADS evaluation, semi-quantitative (SRE) and quantitative (SWE expressed in kPa) elastosonography were performed and relative diagnostic performances, alone and in combination, were compared through ROC curves analysis. In order to maximize the SRE and SWE sensitivity and specificity, their cut-off values were calculated using the Liu test. Bonferroni test was used to evaluate statistically significant differences with a p value < 0.05. Results Sensitivity, specificity, PPV and NPV were, respectively, 71.4%, 82.4%, 62.5%, 87.5% for K-TIRADS baseline US, 85.7%, 94.1%, 85.7%, 94.1% for SRE and 57.1%, 79.4%, 53.3%, 81.8% for SWE (kPa expressed). SRE evaluation showed the best diagnostic accuracy compared to the SWE (kPa expressed) (p < 0.05) and to the K-TIRADS (p > 0.05). The association of SRE with conventional ultrasound with K-TIRADS score increased sensitivity (92.9% vs 71.4%) but decreased the specificity than conventional US alone (76.5% vs 82.4%). Conclusion Strain Elastosonography can be associated with K-TIRADS US examination in the thyroid nodule characterization with indeterminate cytology; in fact, adding the SRE to K-TIRADS assessment significantly increases its sensitivity and negative predictive value. However, further multicenter studies on larger population are warranted.

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