LUO Meiqing CHEN Nianyi Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai
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ChinaYU Zhizhong Shanghai Institute of Testing Technics
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Shanghai
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ChianNING Yuantao ZHOU Xinming Kunming Institute of Precious Metals
,
Kunming
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China CHEN Nianyi
,
Professor
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Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai 200050
,
China
金属学报(英文版)
The electronic structure of Pd-Y-Si glass has been investigated by ESCA and quantum chem- ical calculation.It was found that the valence electrons of Y transferred to Si atoms in this metallic glass,forming polar covalent bonds.Perhaps these strong covalent bonds link Si and Y atoms to form clusters that hinder the process of crystallization.
关键词:
Pd-Y-Si glass
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null
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null
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null
M. Sakane (Department of Mechanical Engineering
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Faculty of Science and Engineering
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Ritsumeikan University
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1-1-1Nojihigashi Kusatsu-shi Shiga
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525-8577
,
Japan)S. Mukai (Power Reactor and Nuclear Fuel Development Corporation
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4002 Narita-cho Oarai-cho Ibaragibun Ibaragi
,
311-13
,
Japan)
金属学报(英文版)
This paper describes new methods for biaxial and triaxial creep testing. Biaxial tension and triaxial tension creep testers were developed. The performance of the machines was described and some test results were discussed. Stress biaxiality had almost no effect on the creep deformation and Mises potential was suitable for describing the creep deformation under biaxial and triaxial stress states. Stress biaxiality had a small influence on prolonging creep rupture time under the constant Mises stress condition.A new triaxial tension creep testing method was discussed together with the shape of the triaxial creep specimen.
关键词:
creep
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null
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null
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null
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null
H.D. Chen
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Y.W. Wang
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J. Xue
金属学报(英文版)
A computer simulation technique for ultrasonic propagation is utilized for the simulation of ultrasonic nondestructive testing (NDT). In this paper, one goal of the simulation is to compute ultrasoniceld radiated by arbitrary transducers into pieces under examination. The other simulates a testing experiment. The simulation approach is based on the model for the computation of the ultrasoniceld in isotropic media radiated from actual NDT transducers. After the eld is known, remaining to be modeled is the interaction between this eld and the scatters (defect) and the echo structure. The model of beam-defect interaction is based on the Kirchho's diffraction approximations theory applied to elastodynamics. We assumed that the incident wave fronts on the defect are plane in the case of a focused immersed transducer and material is isotropic and homogeneous. The simulating results demonstrate that the model in ultrasonic NDT of welds is practical in further research and useful in optimizing testing congurations.
关键词:
ultrasonic testing
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null
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null
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null
Composites Science and Technology
Single-walled carbon nanotube (SWNT) bundles are subject to tensile testing using a self-developed nano-mechanical testing device. The tensile strength of SWNT bundles, as well as reported data of multi-walled carbon nanotubes (MWNTs) and SWNT ropes, are studied by statistical approach. It is shown that the tensile strength distributions of carbon nanotubes (CNTs) or SWNT ropes can be adequately described by a two-parameter Weibull model. Considering the nonlinear elastic behavior of CNTs, a relation between individual CNT and CNT bundle strengths is studied, and a method for determining the tensile strength distribution of individual CNTs or CNT sub-bundles from experimental measurements on CNT bundles is proposed. Therefore the process for determining the strength distributions of individual CNTs can be greatly simplified by testing CNT bundles instead. (C) 2007 Elsevier Ltd. All rights reserved.
关键词:
Carbon nanotubes;Tensile strength;Stress-strain curves;Non-linear;behavior;multiwalled carbon nanotubes;fiber-bundles;hydrocarbons
J.H.Yang
,
J.Chen
金属学报(英文版)
Due to complexities of draw-bead restraining force calculated according to theory and depending on sheet metal forming properties experiment testing system,a simplified method to calculate draw-bead restraining force is put forward by experimental method in cup-shaped drawing process. The experimental results were compared with numerical results and proved agreement. It shows the method is efective.
关键词:
sheet metal forming
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null
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null
Luming LI
,
Songling HUANG
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Peng ZHENG
,
Keren SHI
材料科学技术（英）
The magnetic field distribution characteristics of surface cracks with various widths are discussed based on finite element (FEM) results. The crack depth was 0.20 mm, the width range was from 0.02 to 1.00 mm. The results showed that crack width and lift-off (the distance between surface and sensor) will influence signals. Discussed in this paper is the influence of various lift-off parameters on the peak to peak values of the normal component in magnetic flux leakage testing. The effects can be applied to evaluate surface breaking cracks of different widths and depths. An idea is presented to smooth narrow, sharp crack tips using alternating current (AC) field magnetization.
关键词:
Magnetic flux leakage testing (MFL)
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null
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null
Journal of University of Science and Technology Beijing
The failure of a fluid catalysis and cracking unit (FCCU) in a Chinese refinery was investigated by using nondestructive detection methods, fracture surface examination, hardness measurement, chemical composition and corrosion products analysis. The results showed that the failure was caused by the dew point nitrate stress corrosion cracking. For a long operation period, the wall temperature of the regenerator in the FCCU was below the fume dew point. As a result, an acid fume NOx-SOx-H2O medium presented on the surface, resulting in stress corrosion cracking of the component with high residual stress. In order to confirm the relative conclusion, simulated testing was conducted in laboratory, and the results showed similar cracking characteristics. Finally, some suggestions have been made to prevent the stress corrosion cracking of an FCCU from re-occurring in the future.
关键词:
stress corrosion cracking;fluid catalytic cracking unit;dew point;failure
Zhimin ZHOU
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Yong ZHOU
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Mingjun WANG
,
Chunsheng YANG
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Ji'an CHEN
,
Wen DING
,
Xiaoyu GAO
,
Taihua ZHANG
材料科学技术（英）
Microbridge testing was used to measure the Young's modulus and residual stress of metallic films. Samples of freestanding NiFe film microbridge were fabricated by microelectromechanical systems. Special ceramic shaft structure was designed to solve the problem of getting the load-deflection curve of NiFe film microbridge by the Nanoindenter XP system with normal Berkovich probe. Theoretical analysis of load-deflection curves of the microbridges was proposed to evaluate the Young's modulus and residual stress of the films simultaneously. The calculated results based on experimental measurements show that the average Young's modulus and residual stress for the electroplated NiFe films are 203.2 GPa and 333.0 MPa, respectively, while the Young's modulus measured by the Nano-hardness method is 209.6±11.8 GPa for the thick NiFe film with silicon substrate.
关键词:
Mechanical properties
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金属薄膜
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纳米压痕
