作者: Xing Man Yang, Zhi Zhou, Gang Xi

摘要: Shipborne dropping system is used widely in national defense and ocean engineer. Dropping system is moving with ship in voyage, so it's difficult to analyze precisely the strength of dropping system resulting from the complex dynamics. To solve the problem, firstly based on ADAMS software, in the paper the dynamic model is created and analyzed, and maximum load of every part of dropping system is achieved one by one. Then, static analysis of every part is researched to checkout structural strength based on ANSYS software platform, and improving part structure with weak point. In the paper the method and research make sure that the dropping system is safety and available.

179

作者: Egidio Rizzi, Giuseppe Cocchetti, Giada Colasante, Fabio Rusconi

摘要: In this paper, an analytical and numerical analysis on the collapse mode of circular masonry arches is presented. Specific reference is made to the so-called Couplet-Heyman problem of finding the minimum thickness necessary for equilibrium of a masonry arch subjected to its own weight (Heyman 1977). The note reports the results of an on-going research project at the University of Bergamo. First, analytical solutions are derived in the spirit of limit analysis, according to the classical three Heyman hypotheses and explicitly obtained in terms of the unknown angular position of the intrados hinge at the haunch, the minimum thickness to radius ratio and the non-dimensional horizontal thrust (Colasante 2007, Cocchetti et al. 2010). Results are then compared to Heyman solution. Though only the first of these three characteristics is perceptibly influenced in engineering terms, especially at increasing opening angle of the arch, the treatment settles an important conceptual difference on the use of the true line of thrust, along the line of Milankovitch work. Second, numerical simulations by the Discrete Element Method (DEM) in a Discontinuous Deformation Analysis (DDA) computational environment are provided, to further support the validity of the obtained solutions, with good overall matching of the obtained results (Rusconi 2008, Rizzi et al. 2010).

467

作者: Radu Ibănescu, Cătălin Ungureanu

摘要: The paper presents a new approach to the numerical solution of a particle in equilibrium lying on a circle and subjected to the action of a linear spring. The difficulties of solving such a problem and the Mathcad and Simulink based solutions are presented in [1, 2, 3]. The most important difficulties consist in symbolically solving a forth degree trigonometric equation or in solving a complicated trigonometric inequality. This is why a numerical solution is preferred. The use of the bond graph modelling method for solving this problem of equilibrium is presented in this paper. The bond-graph modelling method is designed only for dynamics and the paper presents the possibility of its adaptation for solving this problem of statics of a particle. This approach can be then applied to solve other problems of statics. From the bond graph model the equilibrium equation and the block diagram model can be obtained. The block diagram model is usually preferred in engineering and, for this reason, the block diagram model obtained from the bond-graph model is shown in the paper together with the numerical results obtained after performing the simulations. The results are compared with those previously obtained in [2, 3].

599

作者: Hua Li Yu, Xi Qing Mu, Mei Ling An

摘要: Researching and analyzing the static characteristic of the hook that functions at the limited load has an important meaning to design larger tonnage hook correctly. Academic analysis structure-strength is implemented on the hook of drillwell DG450. Firstly, based on the characteristic modeling technology, the 3-D entity model of the hook is built used Pro/E. Secondly, the static analysis on three dangerous work condition at ultimate load of the hook is proceeded by FEM software Ansys. The stress and displacement are gained to specify the stress status at the different work condition of the hook. And find out the most dangerous place where the stress is the largest. Important academic elements and data for study and design are provided. The conclusion reference values to design hook and drill safely and prolong the lifetime of drillwell hook.

497

摘要: A heavy-load positioner with series-parallel mechanism was put forward according to the heavy-load positioner’s task demand. Two rotational DOFs were realized by the spherical 3-DOF mechanism with a restricted embranchment instead of traditional gear-driven mechanism, the other by the serial part. The mechanism has the advantages of large workspace, good flexibility and high stiffness-to-weight ratio. The kinematics, statics and singularity of the positioner mechanism were analyzed. The mathematic model of the positioner mechanism was established. Combining the workspace demand of the positioner, dimension optimization of the mechanism was researched. Finally, the kinematics,statics and the singularity analysis of the positioner mechanism was verified through virtual prototype designed with one group of satisfied dimensions.

145

作者: Miloš Lavický, Jan Pěnčík, Štěpán Karlík

摘要: The prefabricated roller blind lintels have become common solution, particularly for the single-leaf masonry structures without external thermal insulation system. These lintels, representing simple system solution, are designed to interrupt thermal bridges in a place of above the window lintel and simultaneously to provide sufficient reliability of load transfer. The actual outdoor blinds contribute to increase the thermal stability in the room in summer and winter season. They prevent overheating of the room in the summer months and reduce heat transmission through a window in the winter. This paper is focused on the design and numerical modelling of the prefabricated roller blind carrier lintels solutions. Methods of elimination of the thermal bridge are demonstrated on the example of a real produced prefabricated lintel. At the same time this paper deals with its structural analysis. Analyses were carried out using the method of numerical modelling, using finite element method and computing software ANSYS.

56

作者: Gao Jun Liu, Tie Zhu Zhang, Huai Xian Yin, Hong Xin Zhang, Lu Zou Zhang, Ben Ming Duan

摘要: The hybrid bus frame is a vehicle’s main bearing component, in which bearing stress state is very complex. In this article, the virtual prototype vehicle model is established to extract dynamic loads between each key connecting parts and the hybrid bus frame. At the same time, the hybrid bus frame finite element model is established to make strength and stiffness analysis with dynamic loads as boundary conditions. The results verify that the strength and stiffness can meet the hybrid bus frame requirement, and the largest deformation and stress area is found. The results also can provide an important basis for correcting the frame structure. What’s more, this paper makes a comparison between the method of the frame finite element analysis based on dynamic loads and the method of the frame finite element analysis based on the statics, concluded a result that the frame finite element analysis based on dynamic loads can more accurately describe the real stress state of the frame and the analysis result is more reliable.

654

摘要: In the paper, a novel new gravity-constrained (GC) three-wire-driven (TWD) parallel robot is proposed. With its mechanism model, three typical kinematics analytical models, including horizontal up-down motion, pitching motion and heeling motion and their corresponding simulations are given in detail. In static analysis, the change of tensions in the wires is calculated based on previous kinematics analysis. The simulation results show the robot has good movement stability. The paper can provide useful materials to study of dynamics and control on wire-driven robot.

302

作者: Xu Zhao Han, Yu Mei Huang, Chun Chen, Hong Yan Liu, Xing Fang Yang

摘要: This paper presents a deep research on 2-DOF planar parallel mechanism during developing a new type of hybrid machine tool. The composition of this planar parallel mechanism is introduced, its direct and inverse kinematics solution equations as well as the solution equations for the speed and the acceleration are deduced, meanwhile, the jacobian matrix is obtained. The statics problems of the parallel mechanism are modeled and analyzed based on principle of virtual work, and the balancing driving force solution equation of the driving part is given. Through the solving process we can see that the direct and inverse solution equations of this mechanism have explicit expressions and convenient to realize real-time control. It forms a solid basis for the design and development of this mechanism.

913

作者: Mouhamadou Diop, Hai Hao, Han Wei Dong, Xing Guo Zhang

摘要: The simulation of magnesium plasticity at the microscopic and mesoscopic scale using space and time-discretized statics and dynamics dislocation was carried out. The complexity of discrete dislocation models dues to the fact that the mechanical interaction of ensembles of such defects is with an elastic nature, and therefore involves long-range interactions. The motion of dislocations or dislocation segments in their respective glide planes are usually described by assuming simple phenomenological viscous flows laws. The formulation of the dislocation dynamics is obtained by the Newton’s Second Law of motion for each dislocation or dislocation segment. The evolution of the dislocation position is obtained by simple difference algorithms.

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