C.W.Ma
金属学报(英文版)
In this work, a parametric approach is presented and utilized to determine the creep properties of weldments; then the model of creep strain for cross weld specimen is given. On the basis of the experimental results, attempt has been made to establish equations of the isochronous stress-strain for weld joint that can predict the function of loading and service time in use of the creep data of base metal and weld metal.
关键词:
isochronous stress-strain curve
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null
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null
International Journal of Fracture
The cohesive zone parameters (separation energy and cohesive strength) and the crack tip triaxialities are compared between a compact tension (CT) and a double edge notched tension (DENT) specimen with smooth side-surfaces. The material is a pressure vessel steel 20MnMoNi55. The cohesive zone parameters are determined by fitting the simulated crack extensions near the midsection to the experimental data. The purpose of the study is to understand the relationship between the cohesive zone parameters and the crack tip stress triaxiality. The results show that for the same cohesive zone parameters the crack tip triaxiality near the midsection is lower in DENT specimens than in CT specimens. When the separation energy is set constant for CT and DENT specimens, the cohesive strength for the DENT specimens should be significantly lower than that for the CT specimens in order to make the simulated crack extensions near the midsection fit to the experimental data. Near the midsection, the cohesive strength and crack tip triaxiality influence each other: the specimen with a higher stress triaxiality has a higher cohesive strength; an increase of cohesive strength results in an increase of the crack tip triaxiality.
关键词:
cohesive zone model;crack growth resistance;crack tip constraint;fracture process zone;micro-ductile fracture;thin aluminum panels;ductile fracture;growth resistance;void;nucleation;model;separation;predictions;interface;elements;work
Masood Shah
,
Catherine Mabru
,
Farhad Rezai-Aria
,
Ines Souki
,
Riffat Asim Pasha
金属学报(英文版)
A finite element analysis of stress intensity factors (K I) in clamped SE(T) C specimens (dog bone profile) is presented. A J-integral approach is used to calculate the values of stress intensity factors valid for 0.125 ≤a/W≤0.625. A detailed comparison is made with the work of other researchers on rectangular specimens. Different boundary conditions are explored to best describe the real conditions in the laboratory. A sensitivity study is also presented to explore the effects of variation in specimen position in the grips of the testing machine. Finally the numerically calculated SIF is used to determine an FCGR curve for AISI H11 tool steel on SE(T) C specimens and compared with C(T) specimen of the same material.
关键词:
Fatigue crack propagation
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null
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null
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null
张红雨
材料保护
为了便于试验参考和标准制订者参考,对盐雾试验标准ISO 9227:2006与ISO 9227:1990从介绍与范围、试验溶液、试验设备、评价盐雾箱腐蚀性能的方法、试样与放置、结果评价与试验报告等方面进行了解读和比较,并建议国家有关部门对国标GB/T 10125-1997进行修订.
关键词:
盐雾试验
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标准
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ISO9227
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对比
Lizeng Ling Shiguo Long Zengsheng Ma Xu Liang
材料科学技术（英文）
In this paper, mechanical properties of Nickel film under residual stress have been systematically examined by finite element method in nanoindentation. It was found that load-displacement curves shifted under elastic residual stress and residual stress exceeded the yield stress for fixed indentation depth. Indentation profiles changed monotonously with compressive and tensile stresses at peak force which determinates contact area observed directly by finite element modeling (FEM). The elastic residual stress has an effect slightly on the hardness but residual stress exceeded the yield stress shows a remarkable effect in nickel film. The hardness increased when residual stress exceeded the yield stress increased under tensile and compressive stress applied to specimen. The relationship between residual stress and hardness was linear. It was found that residual stresses didn0t affect elastic modulus whether elastic residual stress or plastic stress was applied to specimen.
关键词:
Residual stress
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Hardness
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Elastic Modulus
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Indentation profile
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Finite element method
Materials Letters
A new technique for specimen preparation of metal or ceramic powders for transmission electron microscopy (TEM) is presented. The powders were dispersed into ductile metal powders such as Al or Cu etc., which easily agglomerate to fragments or balls when submitted to ball milling. Specimens are then easily obtained from these agglomerates using conventional TEM specimen preparation methods. The procedure was shown to be a versatile means of obtaining accurate and representative specimens of powders for TEM.
关键词:
alloys
