Damage behavior of Cu–Ta bilayered films under cyclic loading

2007 ◽  
Vol 22 (9) ◽  
pp. 2478-2482 ◽  
Author(s):  
X.F. Zhu ◽  
G.P. Zhang ◽  
J. Tan ◽  
Y. Liu ◽  
S.J. Zhu

Damage behavior of Cu–Ta bilayered films bonded to polyimide (PI) substrates has been investigated by cyclic loading tests. Experimental results show that fatigue cracks preferentially initiated in the Ta layer close to the Ta–PI interface and propagated into the Cu layer perpendicular to the interface. The alignment of nanometer-sized Cu grains resulted from the potential GB sliding combined with a small amount of grain rotation was found in the damage zone ahead of the crack tip, and that is suggested to be a likely damage mechanism to accommodate cyclic plastic strain ahead of the fatigue crack tip of the submicrometer-thick Cu layer.

2019 ◽  
Vol 25 (60) ◽  
pp. 655-659
Author(s):  
Shuzo HIROISHI ◽  
Akira OKADA ◽  
Naoya MIYASATO ◽  
Noburu NAKAMURA ◽  
Kenichi MAMURO ◽  
...  

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Qingguang He ◽  
Yanxia Bai ◽  
Weike Wu ◽  
Yongfeng Du

A novel assembled self-centering variable friction (SCVF) brace is proposed which is composed of an energy dissipation system, a self-centering system, and a set of force transmission devices. The hysteretic characteristics and energy dissipation of the SCVF brace with various parameters from low-cyclic loading tests are presented. A finite element model was constructed and tested under simulated examination for comparative analysis. The results indicate that the brace shows an atypical flag-type hysteresis curve. The SCVF brace showed its stable self-centering ability and dissipation energy capacity within the permitted axial deformation under different spring and friction plates. A larger deflection of the friction plate will make the variable friction of this SCVF brace more obvious. A higher friction coefficient will make the energy dissipation capacity of the SCVF brace stronger, but the actual friction coefficient will be lower than the design value after repeated cycles. The results of the fatigue tests showed that the energy dissipation system formed by the ceramic fiber friction blocks and the friction steel plates in the SCVF brace has a certain stability. The finite element simulation results are essentially consistent with the obtained test results, which is conducive to the use of finite element software for calculation and structural analysis in actual engineering design.


2018 ◽  
Vol 91 (1) ◽  
pp. 136-150 ◽  
Author(s):  
Mei Sze Loo ◽  
Jean Benoît Le Cam ◽  
Andri Andriyana ◽  
Eric Robin

ABSTRACT Palm biodiesel is deemed a promising future fuel substitute for conventional diesel fuel. In line with this perspective, necessary changes in the existing diesel engine system are expected in order to address the issue of material compatibility. One typical degradation observed in rubber components exposed to aggressive solvent such as palm biodiesel during the service is swelling. Thus, the investigation of the effect of swelling on the mechanical response under cyclic loading is prerequisite for durability analysis of such components. In this study, filled and unfilled swollen nitrile rubbers are immersed in conventional diesel and palm biodiesel baths until a 5% swelling level is achieved. Both dry and swollen rubbers are subjected to uniaxial cyclic loading tests. The analysis of the mechanical responses has shown that swelling decreases inelastic effects such as hysteresis, stress softening, and permanent set. For both dry and swollen rubbers, fillers are found to have significant effects in the inelastic responses, whereas the effects of solvent and loading rate are comparable.


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