Rapid determination of spectral directional emissivity of infrared stealth materials at high temperature with laser heating

Author(s):  
Chao Qiu ◽  
Sun Hongsheng ◽  
Wang Jiapeng ◽  
Zhang Yuguo ◽  
Cao Qingzheng
2018 ◽  
Vol 165 ◽  
pp. 22022
Author(s):  
Vincent Roué ◽  
Cédric Doudard ◽  
Sylvain Calloch ◽  
Frédéric Montel ◽  
Quentin Pujol D’Andrebo ◽  
...  

The determination of high cycle fatigue (HCF) properties of a material with standard method requires a lot of specimens, and could be really time consuming. The self-heating method has been developed in order to predict S–N–P curves (i.e., amplitude stress – number of cycles to failure – probability of failure) with only a few specimens. So the time-saving advantage of this method has been demonstrated on several materials, at room temperature. In order to reduce the cost and time of fatigue characterization at high temperature, the self-heating method is adapted to characterize HCF properties of a titanium alloy, the Ti-6Al-4V (TA6V), at different temperatures. So the self-heating procedure is adjusted to conduct tests with a furnace. Two dissipative phenomena can be observed on self-heating curves. Because of this, a two-scale probabilistic model with two dissipative mechanisms is used to describe them. The first one is observed for low amplitudes of cyclic loading, under the fatigue limit, and the second one for higher amplitudes where the mechanisms of fatigue damage are activated and are dissipating more energy. This model was developed on steel at room temperature. Even so, it is used to describe the self-heating curves of the TA6V at several temperatures.


2004 ◽  
Vol 59 (2) ◽  
pp. 163-167 ◽  
Author(s):  
B. K. Zuev ◽  
A. A. Korotkov ◽  
V. G. Filonenko ◽  
A. N. Mashkovtsev ◽  
V. P. Zvolinskii

Author(s):  
T. Y. Tan ◽  
W. K. Tice

In studying ion implanted semiconductors and fast neutron irradiated metals, the need for characterizing small dislocation loops having diameters of a few hundred angstrom units usually arises. The weak beam imaging method is a powerful technique for analyzing these loops. Because of the large reduction in stacking fault (SF) fringe spacing at large sg, this method allows for a rapid determination of whether the loop is faulted, and, hence, whether it is a perfect or a Frank partial loop. This method was first used by Bicknell to image small faulted loops in boron implanted silicon. He explained the fringe spacing by kinematical theory, i.e., ≃l/(Sg) in the fault fringe in depth oscillation. The fault image contrast formation mechanism is, however, really more complicated.


2017 ◽  
Vol 45 (2) ◽  
pp. 455-464
Author(s):  
T.T. Xue ◽  
J. Liu ◽  
Y.B. Shen ◽  
G.Q. Liu

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