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Zhefeng Zhang - One of the best experts on this subject based on the ideXlab platform.
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varying tensile Fracture mechanisms of cu and cu zn alloys with reduced grain size from necking to shearing instability
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: P Zhang, S Qu, M X Yang, Guanjun Yang, S D Wu, S X Li, Zhefeng ZhangAbstract:Abstract In ultrafine-grained (UFG) or nanocrystalline (NC) materials, achieving high strength often induces loss of ductility due to the formation of shear Fracture without obvious necking feature. To investigate mechanical properties and Fracture mechanism with reduced grain size, the macroscopic tensile Fracture behaviors of UFG or NC Cu and Cu–Zn alloys were systematically investigated. It is found that the tensile strength and uniform elongation of UFG or NC Cu and Cu–Zn alloys display simultaneously increasing trend. The limitation of ductility can be attributed to the occurrence of shear bands in these materials; their main characteristic, the shear Fracture Angle, decreases with decreasing grain size as well as the degree of necking. The macroscopic Fracture mechanisms are explained using an Ellipse criterion in terms of modification of the stress state in the Fracture zone. It is suggested that the reduction of necking degree results from the geometrical hardening effect due to the change of the stress state. As the degree of necking decreases with decreasing grain size, the tensile shear Fracture Angle decreases too in the UFG/NC materials. Thus improving the geometrical hardening ability may effectively inhibit the formation of shear Fracture, as the nucleation of shear bands becomes difficult.
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difference in compressive and tensile Fracture mechanisms of zr59cu20al10ni8ti3 bulk metallic glass
Acta Materialia, 2003Co-Authors: Zhefeng Zhang, J Eckert, L SchultzAbstract:The compressive and tensile deformation, as well as the Fracture behavior of a Zr59Cu20Al10Ni8Ti3 bulk metallic glass were investigated. It was found that under compressive loading, the metallic glass displays some plasticity before Fracture. The Fracture is mainly localized on one major shear band and the compressive Fracture Angle, theta(C), between the stress axis and the Fracture plane is 43degrees. Under tensile loading, the material always displays brittle Fracture without yielding. The tensile Fracture stress, sigma(F)(T), is about 1.58 GPa, which is lower than the compressive Fracture stress, sigma(F)(C)( = 1.69 GPa). The tensile Fracture Angle, sigma(F)(T), between the stress axis and the Fracture plane is equal to 54degrees. Therefore, both theta(C) and theta(T) deviate from the maximum shear stress plane (45degrees), indicating that the Fracture behavior of the metallic glass under compressive and tensile load does not follow the von Mises criterion. Scanning electron microscope observations reveal that the compressive Fracture surfaces of the metallic glass mainly consist of a vein-like structure. A combined feature of veins and some radiate cores was observed on the tensile Fracture surfaces. Based on these results, the Fracture mechanisms of metallic glass are discussed by taking the effect of normal stress on the Fracture process into account. It is proposed that tensile Fracture first originates from the radiate cores induced by the normal stress, then propagates mainly driven by shear stress, leading to the formation of the combined Fracture feature. In contrast, the compressive Fracture of metallic glass is mainly controlled by the shear stress. It is suggested that the deviation of theta(C) and theta(T) from 45degrees can be attributed to a combined effect of the normal and shear stresses on the Fracture plane. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.
Job N Doornberg - One of the best experts on this subject based on the ideXlab platform.
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articular coronal Fracture Angle of posteromedial tibial plateau fragments a computed tomography Fracture mapping study
Injury-international Journal of The Care of The Injured, 2019Co-Authors: Rik J Molenaars, Lucian B Solomon, Job N DoornbergAbstract:Abstract Objectives The purpose of this study is to analyze posteromedial fragment morphology using two-dimensional computed tomography Fracture mapping and to compare posteromedial fragment morphology in various Schatzker type tibial plateau Fractures. Materials & methods One hundred twenty-seven consecutive AO/OTA B- and C-type tibial plateau Fractures were retrospectively analyzed using 2DCT Fracture mapping. The posteromedial articular Fracture Angle and articular surface areas of all Fractures with posteromedial fragments were calculated. Based on biomechanical studies, posteromedial fragments with coronal Fracture Angles >68° were considered amenable for anterolateral stabilization with standardized plating. Kruskall-Wallis non-parametric test was used for statistical comparison of morphological features of posteromedial fragments between the various Schatzker types. Results Forty-seven out of 127 tibial plateau Fractures included a posteromedial fragment. The mean posteromedial articular Fracture Angle was 44° (range: 2°-90o, standard deviation: 23°). Forty fragments (85%) had a Fracture Angle of Discussion and conclusion Posteromedial fragments commonly occur not only in Schatzker type V and VI, but also in Schatzker type IV tibial plateau Fractures. Eighty-five percent of tibial plateau Fractures with a posteromedial fragment may benefit from non-standard customized lateral plating, or may require an additional medial or posterior surgical approach for Fracture-specific fixation to optimize screw purchase and biomechanical stability.
E. Peleg - One of the best experts on this subject based on the ideXlab platform.
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SCAPHOID Fracture Angle: THREE DIMENSIONAL ANALYSIS OF Fracture MORPHOLOGY
2018Co-Authors: S. Luria, Y. Schwartz, R. Wollstein, P. Emelif, G. Zinger, E. PelegAbstract:PurposeKnowing the morphology of any Fracture, including scaphoid Fractures, is important in order to determine the Fracture stability and the appropriate fixation technique. Scaphoid Fractures are...
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3-dimensional analysis of scaphoid Fracture Angle morphology.
The Journal of hand surgery, 2015Co-Authors: S. Luria, R. Wollstein, G. Zinger, Yonatan Schwarcz, Patrick I. Emelife, E. PelegAbstract:Purpose Scaphoid Fractures are classified according to their 2-dimensional radiographic appearance, and transverse waist Fractures are considered the most common. Our hypothesis was that most scaphoid Fractures are not perpendicular to the longitudinal axis of the scaphoid (ie, not transverse). Methods Computerized 3-dimensional analyses were performed on 124 computed tomography scans of acute scaphoid Fractures. Thirty of the Fractures were displaced and virtually reduced. The Angle between the scaphoid's first principal axis (longitudinal axis) and the Fracture plane was analyzed for location and displacement. The distal radius articular surface was used to depict the volar–dorsal vector of the wrist. Results There were 86 Fractures of the waist, 13 of the distal third, and 25 of the proximal third. The average Angle between the scaphoid longitudinal axis and the Fracture plane was 53° for all Fractures and 56° for waist Fractures, both differing significantly from a 90°, transverse Fracture. The majority of Fracture planes were found to have a volar distal to dorsal proximal (horizontal oblique) inclination relative to the volar–dorsal vector. Conclusions Most waist Fractures were horizontal oblique and not transverse. According to these findings, fixation of all Fractures along the longitudinal axis of the scaphoid may not be the optimal mode of fixation for most. A different approach may be needed in accordance with the Fracture plane. Type of study/level of evidence Diagnostic II.
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SCAPHOID Fracture Angle: THREE DIMENSIONAL ANALYSIS OF Fracture MORPHOLOGY
Journal of Bone and Joint Surgery-british Volume, 2013Co-Authors: S. Luria, Y. Schwartz, R. Wollstein, P. Emelif, G. Zinger, E. PelegAbstract:Purpose Knowing the morphology of any Fracture, including scaphoid Fractures, is important in order to determine the Fracture stability and the appropriate fixation technique. Scaphoid Fractures are classified according to their radiographic appearance, and simple transverse waist Fractures are considered the most common. There is no description in the literature of the 3-dimensional morphology of scaphoid Fractures. Our hypothesis was that most scaphoid Fractures are not perpendicular to its long axis, i.e. they are not simple transverse Fractures. Methods A 3-dimensional analysis was performed of CT scans of acute scaphoid Fractures, conducted at two medical centers during a period of 6 years. A total of 124 scans were analysed (Amira Dev 5.3, Visage Imaging Inc). Thirty of the Fractures were displaced and virtually reduced. Anatomical landmarks were marked on the distal radius articular surface in order to orient the scaphoid in the wrist. Shape analysis of the scaphoids and a calculation of the best fitted planes to the Fractures were carried out implementing principal component analysis. The Angles between the scaphoid9s first principal axis to the Fracture plane, articular plane and to the palmar-dorsal direction were measured. The Fractures were analysed both for location (proximal, waist and distal) and for displacement. Results There were 86 Fractures of the waist (76 percent), 13 of the distal third and 25 of the proximal third. The average Angle between the first principal axis of the scaphoid and the Fracture plane was 52.6 degrees (SD 17) for all Fractures, 55.6 degrees (SD 17.2) for the waist Fractures, both differing significantly from a right Angle (p In contrast, a significant difference was found between the displaced and non-displaced Fractures when evaluating the orientation of the scaphoid long axis in relation to the articular plane (139.8 degrees with reduction versus 148.2 without; p=0.036) Conclusions Most waist Fractures were found to be horizontal oblique in relation to the long axis of the scaphoid and not transverse. Although the Fracture Angle could not explain displacement of the Fracture, we found that the orientation of the scaphoid9s long axis in relation to the radial articular surface was correlated with Fracture displacement. According to these findings, fixation of all Fractures along the long axis of the scaphoid should not be the optimal mode of fixation. Optimal fixation of acute scaphoid Fractures may call for better analysis of each Fracture configuration and the fixation should be guided by this analysis.
Jitang Fan - One of the best experts on this subject based on the ideXlab platform.
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Evaluating the material strength from Fracture Angle under uniaxial loading
Frontiers of Structural and Civil Engineering, 2018Co-Authors: Jitang FanAbstract:The most common experimental methods of measuring material strength are the uniaxial compressive and tensile tests. Generally, shearing Fracture model occurs in both the tests. Compressive strength is higher than tensile strength for a material. Shearing Fracture Angle is smaller than 45° under uniaxial compression and greater than 45° under uniaxial tension. In this work, a unified relation of material strength under uniaxial compression and tension is developed by correlating the shearing Fracture Angle in theory. This constitutive relation is quantitatively illustrated by a function for analyzing the material strength from shear Fracture Angle. A computational simulation is conducted to validate this theoretical function. It is full of interest to give a scientific illustration for designing the high-strength materials and engineering structures.
Yanxin Zhao - One of the best experts on this subject based on the ideXlab platform.
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Stalk architecture, cell wall composition, and QTL underlying high stalk flexibility for improved lodging resistance in maize.
BMC plant biology, 2020Co-Authors: Xiaqing Wang, Zi Shi, Zhang Ruyang, Xuan Sun, Jidong Wang, Shuai Wang, Ying Zhang, Yanxin ZhaoAbstract:Background Stalk Fracture caused by strong wind can severely reduce yields in maize. Stalks with higher stiffness and flexibility will exhibit stronger lodging resistance. However, stalk flexibility is rarely studied in maize. Stalk Fracture of the internode above the ear before tasseling will result in the lack of tassel and pollen, which is devastating for pollination in seed production. In this study, we focused on stalk lodging before tasseling in two maize inbred lines, JING724 and its improved line JING724A1 and their F2:3 population. Results JING724A1 showed a larger stalk Fracture Angle than JING724, indicating higher flexibility. In addition, compared to JING724, JING724A1 also had longer and thicker stalks, with a conical, frustum-shaped internode above the ear. Microscopy and X-ray microcomputed tomography of the internal stalk architecture revealed that JING724A1 had more vascular bundles and thicker sclerenchyma tissue. Furthermore, total soluble sugar content of JING724A1, especially the glucose component, was substantially higher than in JING724. Using an F2:3 population derived from a JING724 and JING724A1 cross, we performed bulk segregant analysis for stalk Fracture Angle and detected one QTL located on Chr3: 14.00-19.28 Mb. Through transcriptome data analysis and ∆ (SNP-index), we identified two candidate genes significantly associated with high stalk Fracture Angle, which encode a RING/U-box superfamily protein (Zm00001d039769) and a MADS-box transcription factor 54 (Zm00001d039913), respectively. Two KASP markers designed from these two candidate genes also showed significant correlations with stalk Fracture Angle. Conclusions The internode shape and glucose content are possibly correlated with stalk flexibility in maize. Two genes in the detected QTL are potentially associated with stalk Fracture Angle. These novel phenotypes and associated loci will provide a theoretical foundation for understanding the genetic mechanisms of lodging, and facilitate the selection of maize varieties with improved flexibility and robust lodging resistance.
