The fatigue life estimation of notched specimens under random loading

The LY12-cz aluminium alloy sheet specimens with a central hole were tested under constant amplitude loading, Rayleigh narrow band random loading and a typical fighter broad band random loading. The fatigue life was estimated by means of the nominal stress and the Miner's rule. The stress cycles were distinguished by the rainflow count, range count and peak value count, respectively. The comparison between the estimated results and the test results was made. The effects of random loading sequence and small load cycles on fatigue life were also studied.

Microcracks Propagation in One Al/SiCp under Impact Loading

Numerous microcracks propagation in one metal matrix composite, Al/SiCp under impact loading was investigated. The test data was got with a specially designed impact experimental approach. The analysis to the density, nucleating locations and distributions of the microcracks as well as microstructure effects of the original composite was received particular emphasis. The types of microcracks or debonding nucleated in the tested composite were dependent on the stress level and its duration. Distributions of the microcracks were depended on that of microstructures of the tested composite while total number of microcracks in unit area and unit duration, was controlled by the stress levels. Also, why the velocity was much lower than theoretical estimations for elastic solids and why the microcracks propagating velocities increased with the stress levels' increasing in current experiments were analysed and explained.

Failure process analysis of cement under explosive loading with a generalized driven nonlinear threshold model

The microstructural heterogeneity and stress fluctuation play important roles in the failure process of brittle materials. In this paper, a generalized driven nonlinear threshold model with stress fluctuation is presented to study the effects of microstructural heterogeneity on continuum damage evolution. As an illustration, the failure process of cement material under explosive loading is analyzed using the model. The result agrees well with the experimental one, which proves the efficiency of the model.

Wave loading on floating platforms by internal solitary waves

Morison's equation is used for estimating internal solitary wave-induced forces exerted on SPAR and semi-submersible platforms. And the results we got have also been compared to ocean surface wave loading. It is shown that Morison's equation is an appropriate approach to estimate internal wave loading even for SPAR and semi-submersible platforms, and the internal solitary wave load on floating platforms is comparable to surface wave counterpart. Moreover, the effects of the layers with different thickness on internal solitary wave force are investigated.