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Corrosion pits will lead to local stress concentration on the surface of steel strands and even shorter fatigue life and worse mechanical properties of steel strands. In order to explore the corrosion mechanics of steel strands to predict the fatigue life, accelerated salt spray corrosion test is carried out to simulate the corrosion laws of steel strands and record the changes of the corrosion degrees during the experiment, considering the coupling effects of alternating loads and chloride environment. Besides, the impact of stress amplitudes on the corrosion degrees of steel strands is quantitatively studied by the corrosion weight loss, and corroded steel strands in experiment are graded according to the corrosion weight loss to test the mechanical properties, respectively; the results show that the corrosion weight loss and tensile strength of steel strands obey the exponential distribution, and the relationship with elongation is linear. In addition, the relationships between the stress concentration coefficient and the pit length, width, and depth are obtained; with the three-dimensional linear regression theory, the accuracy of the regression model is verified by t-value test, laying a foundation for predicting the corrosion life of the cables.

A loading device was developed in this paper basing on corrosion experiments of conventional metal and cable through collecting previous research about cable stress corrosion. This newly developed device makes loading possible under low frequency alternating stress and environmental corrosion coupling. Through the different condition for the steel strands corrosion experiments show that the speed of steel strand corrosion in alternating stress load is faster than non-stress and static-stress in the same conditions. The co-influence of corrosion and stress to the ductility of strand, the influence of alternating load peak and frequency to corrosion velocity were respectively analyzed. Three groups of verification experiment results show that the plastic deformation effects caused by the tension are much larger than the corrosion. Corrosion velocity of the specimens that reached threshold value under tensile stress is 1.47 times faster than the other three peak load specimens. And the ductility is not sensitive to low frequency, the ductility of the specimen is associated with tension and corrosion.

A series of plate impact experiments have been conducted on alumina specimens with different thicknesses through the light gas gun in order to further investigate the delayed failure phenomenon under shock loading. With the aid of the velocity interferometer system for any reflector, an evident recompression signal has been observed in the temporal curve of the rear free surface velocity of the specimen, which indicates the generation of the failure wave. According to the experimental results, the failure wave propagation was probed. The results show that the failure wave generates a delayed time of ,0?105 ms behind the shock wave front and propagates into the stressed body with a velocity of ,5051 m s 21 under the impact stress of 7?16 GPa. The physical mechanism of the failure wave was further discussed.