Search

The geometric nonlinearity caused by gravity can not be neglected when conducting ground modal test of solar array on the ground. So a new model updating method for flexible structures considering the influence of gravity is proposed in this paper. First, the stress stiffness matrix in ground environment is derived, then the modes are calculated by solving the generalized eigenvalue problem. After matching tested mode shapes with calculated ones, the sensitivity analysis of the parameters is carried out. Then the proper parameters are chosen and updated by using a iteration process. A numerical simulation of a deployed and locked solar array is conducted, it is found that gravity has influence on the modal frequency. The elastic parameters of the single panel and the connection stiffness of the hinges between different solar array panels are updated step by step. The study shows that proposed method is fast and accurate. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study of geochronology, in situ clinopyroxene mineralogy, geochemistry and isotope geology for the Triassic mafic magmatism of the central Tibetan Plateau. Moreover, the results are used to understand the development of a continental back-arc basin and the generation of back-arc basin magmatism. Zircon U-Pb isotope analyses indicate that these rocks were formed during the Middle Triassic (c. 231 Ma). Both the mafic rocks and the trapped melt calculated by the clinopyroxene/melt partition coefficient (Dcpx/melt) exhibit distinct enrichments in light rare earth elements (LREE) and Th with pronounced depletions in Nb and Ta, which are similar to the geochemical composition of typical continental back-arc basin basalts. Geochemical features and isotopic variations indicate that the mafic melts originated from a depleted mantle modified by c. 10% crustal components. The ratios of Zn/Fet and REE further suggest a spinel-bearing peridotite source. Considering other regional geological data, we argue that the origin of Triassic mafic magmatism should be attributed to the extension of a continental back-arc basin. Slab rollback and mantle plume activity played vital roles in the formation and development of a continental back-arc basin in the central part of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Based on Finite element method-Direct boundary element method (FEM-DBEM) and Finite element method-Indirect boundary element method (FEM-IBEM) approach, the bearing cylinder-skin structural-acoustic coupling models considering onlyinternalorexternalacoustic field and both inside and outside acoustic field are established. The structural-acoustic coupling analysis under random base excitation is researched. Further, the coupled effect of internal/external acoustic field and structural-acoustic coupling on the inherent characteristics and dynamic response is analyzed with the emphasis on. Results show that coupled effect results in the decrease of its nature frequencies, but has no effect on the modal shape. Single acoustic field effect results in the increase of the nature frequencies more than both inside and outside acoustic field effect. The coupled effect also results in the overall decrease of dynamic response, but causes increase of the dynamic responsein the places where is parallel to the direction of excitation. In addition, influence of internal acoustic field on the dynamic responseis greater than the external acoustic field. [ABSTRACT FROM AUTHOR]