Abstract: Equal Channel Angular Extrusion (ECAE) has become a very popular tool for studying the evolution of microstructure and properties under severe plastic deformation. It is believed that the stress-strain characteristics are uniform in a cross-section of the billet and this uniformity of the stress-strain distribution ensures the uniformity of microstructure and mechanical properties in ECAE processed billet. However, some experimental data such as the fracture of the extruded billet, which is initiated at the inner surface of the sample, has caused doubts about uniformity of stress-strain distribution. This non-uniformity has been proved recently by Finite Element Simulation.
In this paper the studies of the positive role of the applied back-pressure during ECAE are reviewed and the influence of a back-pressure on the uniformity of the stress-strain distribution, strain localisation, die corner filing, and the prevention of fracture is shown. The effect of back-pressure on grain refinement and improvement in mechanical properties is emphasized. The paper summarises our results from over seven years of work using a unique machine for ECAE with computer-controlled back-pressure and velocity of the backward punch.
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Authors: Xiao Ning Zhang, Qing Wang
Abstract: This paper presents a simulation method on shielding effectiveness(SE). The method is
completely general and able to optimize shielding materials. We found a sandwich structure that it can
efficiently shield plane wave, using this simulation method. The relationship of film thickness and its
skin depth was investigated in this study. Two-dimensional curves and three-dimensional graphs were
calculated by tri-layer SE formulas. A sandwich structure, which is 3μm iron-brass-iron films, is
capable of excellent shielding properties: the SE is between -73dB and -100dB in the frequency range
of 1MHz~10MHz. Another sandwich structure with 12μm thickness of brass-iron-brass films can
offer -680dB shielding attenuation. Simulation experiments indicate that sandwich films with
diamagnetic and ferromagnetic layers have outstanding contribution on SE.
1613
Authors: Yin Fang Jiang, Lei Fang, Zhi Fei Li, Zhen Zhou Tang
Abstract: As a new lightweight material and new technique,Tailor Rolled Blanks has a good prospect in energy-saving environmental protection and the future development of the automobile industry, formability window of Tailor Rolled Blanks at blank-holder force has important practical significance. Based on the research of a square box TRB, the paper proposes a theory of TRB’ formability window, also with the usage of an ABACUS finite element software to simulate the TRB sheet in the course of the critical wrinkling BHF curve and critical fracture BHF curve, to establish TRB formability window under the condition of blank holder force. The results not only show that the square box of TRB has the security zone in the deep drawing process, but also has got the wrinkling and fracture areas of the square box.
488
Authors: Mohsen Loh-Mousavi, Amir Masoud Mirhosseini, Ghasem Amirian
Abstract: In recent years, tube hydroforming has been applied in automobile and airplane industries, to decrease weight. In general, the determination of internal pressure path is a key factor in improving the formability in tube hydroforming. One of the effective methods in improving the tube hydroforming is using the pulsating internal pressure path. In this research, hydroforming of bi-layered tubes under pulsating pressure in x-shaped die is simulated by means of three dimensional finite element method. Some numerical results were compared with experimental results and show good correlation. Influence of pulsating pressure on the thickness and stress distribution have been also studied. It was shown that pulsating pressure improves the formability in hydroforming of bi-layered tubes via continues and gradual removing returnable wrinkling which is caused by a low pressure in this process. In addition, effect of some key parameters such as friction and die corner filling have been investigated.
5
Authors: Hui Hui Zhao, Wen Fang Zhang
Abstract: The application of ABAQUS finite element software non-linear finite element analysis of brick masonry walls with structural column. Build three brick masonry wall models, and analysis of the damage form of the wall under different vertical compressive stress and horizontal force. Thus the analysis result compared with the calculation result of the relevant specification formula, in order to get validate compression influence of masonry aseismic walls. It turned out that different vertical compressive stress effect the shear capacity, and failure mode of brick masonry wall structure with a structural column.
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