S. J. Chen
,
S. Y. Yin
,
L. Feng and L. Y. Li( 1) School of Materials Science and Engineering
,
Beijing Polytechnic University
,
Beijing 100022
,
China 2)National Key Laboratory of Advanced Welding Production Technology
,
HIT
,
Harbin 150001
,
China)
金属学报(英文版)
Based on the existing component models in the Pspice software package, a combined model for Insulat- ed the Bipolar Transistor (IGBT) is established, in which a non - linear is introduced to represent the parasitic capacitance. Using this model, computerized simulation is conducted for the FB - ZVZCS - PWM soft - ewitching converter,the switching and energy-transferring characteristics of the components are analyzed.The simulation results are testified by experiments.It is proved that by abopting appropriate models,computerized simulation becomes an effective tool for investigation of arc welding inverter power source.
关键词:
arc welding inverter
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null
,
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S. Y. Yin
,
L. Feng
,
J. Z. Ding and S. J. Chan( 1) Beijing Polytechnic University
,
Beijing 100022
,
China 2) National Key Laboratory of Advanced Wdlding Production Technology
,
HIT
,
Harbin 150001
,
China)
金属学报(英文版)
Based on the theory of stability of the liquid metal under the action of surface tension,a physical mod- el is established for the mechanisms of the bead formation deferct' humping', which is generated during high - speed welding.A boundary function is introduced to correct the model,theoretical results got by the model correspond well with the experimental phenomena. A two - dimensional conducting model is adoopted in the simulation of the temperature field during high - speed welding.Finally, the factors acting upon the stability of liquid metal are analyzed.
关键词:
high - speed welding
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null
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null
X. Y. Li
,
X. T. Tian and H. C. Zhu( 1)Weldng Division
,
Beijing Polytechnic University
,
Beijing 100022
,
China 2)National ho. of Advanced Welding Technology
,
HIT
,
Harbin 150001
,
China)
金属学报(英文版)
Mismatching is one of the basic characteristics of welded joints.Overmatched welded joint with a crack in hard weld is simplified as a cracked body of CCP type SHS (a hard bar sandwiched between two soft material with a crier perallel to the interface ) in this paper.Effects of mechanical heterogeneity on fatigue crack growth and crack closure of this model are studied by experimental and elastic - plastic finite element methods. It is found that, residual plastic deformation remaining in the wake of a growing crack tip, which cases crack closure,is affected the plastic deformation in adjacent soft mate- rial near by the crack tip. Both the shape of crack tip plastic zone and stress distribution ahead of crack tip in heterogeneous cracked body are different from that of homogeneous one. Crack closure (open- ing) loads are estimated by investigating the changes of crack tip opening displacement during fatigue loading, and a new model of crack oening process is presented. Because of the difference in the effect of mechanical heterogeneity on displacement of non - fatigue crack and fatigue crack, conventional CTOD can not reflect the real deformation at crack tip of SHS specimens.
关键词:
welded joint
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null
,
null
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null
QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.
关键词:
stress corrosion cracking
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null
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null
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null
