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Hongwei Deng,Songtao Yu,Junren Deng,Bo Ke,Feng Bin 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.5
To gain a further understanding of Freeze-Thaw weathering effect on the damage of sandstone from the perspective of energy analysis, uniaxial static compression tests were conducted on sandstone samples that suffered 0, 20, 60, 100 and 140 freezingthawing cycles. Then total input strain energy, releasable elastic strain energy, dissipated energy and freezing-thawing induced damage of samples under uniaxial static compression tests were calculated and analyzed. In the mean time, the energy absorption of sandstone under dynamic loading tests (SHPB (Split-Hopkinson pressure bar) experiments) were cited and made a contrast with the dissipated energy of samples under uniaxial static compression tests. The results show that the tangent modulus, total input strain energy, releasable elastic strain energy and dissipated energy of samples decrease with Freezing-Thawing cycles go on, while the freezing-thawing induced damage grow with freezing-thawing cycles increase. In term of energy used for destroying rock samples in different test modes, less energy is needed for destroying samples in uniaxial static compression tests and it decreases with F-T cycles increase, while more energy is needed for destroying samples in dynamic impact loading and it increases with F-T cycles increase. In addition, the number of fragments of broken sample increase with the F-T cycles both in uniaxial static compression tests and dynamic loading tests, and sample under dynamic loading tests is more broken than sample under uniaxial static compression tests.
Analysis of the repeatability of a deployable space tri-prism mast based on the Monte Carlo method
Mingxing Gao,Rongqiang Liu,Hongwei Guo,Zongquan Deng 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3
Space deployable mast, which is a supporting mechanism, especially for a space telescope, requires high repeatability. In this study, a deployed space tri-prism mast was taken as the research object, and the change of a tensional cable’s tension force was equivalent to an external load. Based on the accurate stiffness model of the mast, the repeatability of the tri-prism mast was calculated by using the Monte Carlo method. Then, the influences of the number of units, the change in the tension force, the thickness of the linkage, and the radius of the tensional cable on the repeatability of the tri-prism mast were studied. Moreover, the correctness of the analytical model was verified by the repeatability experiments. Results demonstrated that the proposed method could be used to analyze the repeatability of tri-prism mast. This study provided references and suggestions for the design of high-precision space deployable mast.