Applied Mechanics and Civil Engineering II

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Authors: Lei Guo, Yong He, Xian Feng Zhang, Nian Song Zhang, Chun Xu Pang
Abstract: A review on the numerical studies about KE(kinetic energy) penetrator into concrete target with mass loss is presented. There are two main ways to study the mass loss in numerical simulation: finite-element method and abrasion iterative algorithm. For each method, detailed introduction is given at home and abroad. A summary of their research, including their advantages and disadvantages, is described. Finally, some research proposals are given for further study.
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Authors: Wei Liu, Xiao Zhe Wang
Abstract: In the source region, numerical simulation usually has a bad result. So, a two-dimension point-source FDTD simulation has been completed in this paper. By analyzing the data nearby the source, some results are gained. In the source region, for its own characteristic of FDTD, reflect waves’ reaching time doesn’t agree with its expectation in theory. But the data can be corrected by counter deduction. As an application, a level interface inversion is done by using the corrected data and a good result is obtained.
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Authors: Yao Yao, Li Xun Cai, Chen Bao, Han Jiang
Abstract: For front-force compact tension specimen (FFCT), based on the refined results of the relationship between crack tip opening displacement and load line crack opening displacement from Finite Element Analysis (FEA), the influences of material properties and plastic deformation near the crack tip have been analyzed. A simplified and accurate transform formula for FFCT specimens is presented in this paper, and the error analysis is conducted.
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Authors: Mao Lin Tang, Ya Guang Du, Rui Li Shen, Kun Yan
Abstract: To study the behavior changing between cable characteristics and beam characteristics, the geometric shape calculation formulae for tension components with bending stiffness are derived from ones with the boundary conditions of two ends hinged, one hinged joint and the other fixed and two ends fixed respectively. Then, using the concept of tension stiffness, the effects of Cable Characteristic Parameter on the geometric shape of tension components are studied. Analyses indicate that with the increase in the value of the Cable Characteristic Parameter, the cable characteristics of components become more obvious. That is, a bar with enormous tension can be calculated as a cable element even if its bending stiffness is large. In structure finite element analysis, more storage space and computing time could be saved as long as components are simplified with cable elements other than beam elements, the simplification should be carried out basing on the Cable Characteristic Parameter. Calculation results on a hollow beam verify that when tension increases, components’ mechanical properties gradually change from beam characteristics to cable characteristics and eventually they tend to be identical with the theoretical calculation of cable structure.
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Authors: Qi Chao Xue, Guang Ping Zou, Ye Wu, Hai Lin Xiong, Meng Chai
Abstract: Based on Reissner’s sandwich plate theory, the critical globlal buckling equation of sandwich plate with ribs is deduced by energy method under simple support boundary conditions. And the critical buckling solution is obtained and discussed here. Afterwards a rectangular sandwich plate with steel faceplate and polyurthane core is taken as an example. The influence on critical global buckling stress with different inertia moments in rectangular sandwich plates are discussed. simularly the effect of the lengh ratio of two sides and the thickness of rectangular sandwich plate are also studied.
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Authors: Chang Hong Chen, Ying Huang, Jian Shan
Abstract: Based on the traditional mechanical model of straight beam element, the paper makes a systematic analysis and research on the pre-twisted beam finite element numerical model. Firstly, the paper proposed the pre-twisted Euler beam element mode, the mode uses 2 node and 12 freedom degrees, the element axial and torsion displacements use 2 nodes Lagrange interpolation function, bending displacement still use the cubic displacement. Secondly, the paper studies a new pre-twisted Timoshenko beam element mode, the proposed new Timoshenko beam element takes separate interpolation polynomial functions both flexure bending and rotation displacement. According to the relationship between bending moment and shear, the relationship between of bending displacement and angle displacement is derived, which is more accurate to consider the effects of shear deformation. Finally, by calculating the pre-twisted rectangle cantilever beam example, and contrasting three-dimensional solid finite element using ANSYS, the comparative analysis results show that pre-twisted Timoshenko beam element mode has good accuracy.
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Authors: Hong De Wang, Qiang Yang, Shu Hua Pan, Wei Cui Ding, Yong Long Gao
Abstract: Taking the Lijiapo landslide in Three Gorges Area as an example, the study on the impact of seepage field changes caused by water level fluctuation on reservoir landslide stability was carried out. In order to find out the variation in slope stability when the reservoir water level changes at different rate, the stability calculation model was established adopting the Seep module and Slope module of Geoscience software GeoStudio, and calibrated with a long sequence of real-time monitoring data, based on the landslide survey data and test data. The results show that the reservoir landslide stability affected by the seepage field changes with changing reservoir level is controlled by a variety of factors, including the hydrodynamic pressure, hydrostatic pressure, uplift force, physical and mechanical properties (с, φ value change). When the water level fluctuates at a high rate, the impact of the seepage field changes on the stability is mainly affected by the pore water pressure before the stability reaches the extremum, while after the extremum, with the further infiltration or drainage of reservoir water, it is mainly affected by the change of physical and mechanical properties. When the water level fluctuates at a lower rate, the pore water pressure, uplift force and physical and mechanical properties are the dominant factors.
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Authors: Guang Qian Du, Chang Zhi Zhu, Xi Ping Zhang
Abstract: A new technology of dynamic compaction method is successfully used to reinforce the saturated soft soil foundation. The field monitoring laws of lateral displacement of the foundation after dynamic compaction, the increasing and dissipation regularity of the excess pore water pressure are analyzed and discussed. The improvement effect is verified by static cone penetration test and loading test. The determination methods of effective reinforcement depth after dynamic compaction are put forward. The practice shows that, by field-testing methods, such as static cone penetration test and pore water piezometer test, to determine the effective reinforcement depth after dynamic compaction and other design parameters is reliable.
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Authors: Xue Ning Ma, Xu Wang
Abstract: The settlement prediction is an important problem to railway subgrade design and construction in the collapsible loess region. Prediction of subgrade settlement is more methods through measured data in practical engineering. Based on the long-term monitoring data of settlement of loess subgrade at Lanzhou-Wuwei second-railway line, a new prediction model was put up and contrasted with other models such as Hyperbolic model, Logarithm model, exponential model and Poisson’s model. The results showed that the new model could be better predict settlement laws of loess subgrade, and agreed well with hyperbolic model forecast results, and proved the correctness of the model.
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