Current Issue : July - September Volume : 2018 Issue Number : 3 Articles : 5 Articles
The collapse of transmission towers involves a series of complex problems, including geometric nonlinearity,material nonlinearity,\ndynamic nonlinearity, and the failure of members. Simulation of the process of collapse is difficult using traditional finite element\nmethod (FEM), which is generated from continuum and variation principle, whereas the finite particle method (FPM) enforces\nequilibrium on each point. Particles are free to separate from one another, which is advantageous in the simulation of the structural\ncollapse. This paper employs the finite particle method (FPM) to simulate the collapse of a transmission steel tower under\nearthquake ground motions; the three-dimensional (3D) finite particle model using MATLAB and the 3D finite element model\nusing ANSYS of the transmission steel tower are established, respectively. And the static and elastic seismic response analyses\nindicate that the results of the FPM agree well with those of the FEM. To simulate the collapse of the transmission steel tower, a\nfailure criterion based on the ideal elastic-plastic model and a failure mode are proposed. Finally, the collapse simulation of the\ntransmission steel towers subjected to unidirectional earthquake ground motion and the collapse seismic fragility analysis can be\nsuccessfully carried out using the finite particle method. The result indicates that the transmission steel tower has better seismic\nsafety performance and anticollapse ability....
A simplified finite element model for large polymer electrolyte membrane fuel cell (PEMFC) stack consisting of ten cells is\nestablished in order to investigate the internal structure deformation. It is found that the interface slippage occurs when the bipolar\nplate (BP) and membrane electrode assembly (MEA) are subjected to vertical impact acceleration. Based on this three-dimensional\nmodel, the influence of the friction coefficient between BP andMEAon the relative slippage can be analyzed efficiently.Thedivision\nlayer of relative slippage is found and its vibration rule is discussed. It is observed that increasing the magnitude of impact vibration\nhas most significant effect on the movement of the division layer, and the two variables are linearly related when impact acceleration\nis greater than 5 g. This work provides important insight into the choice of the friction coefficient....
This paper presents welding torch pose model and interpolation algorithm of trajectory control of saddle-shaped weld formed\nby intersection of two pipes; the working principle, interpolation algorithm, welding experiment, and simulation result of the\nautomatic welding system of the saddle-shaped weld are described. A variable angle interpolation method is used to control the\ntrajectory and pose of the welding torch, which guarantees the constant linear terminal velocity. The mathematical model of the\ntrajectory and pose of welding torch are established. Simulation and experiment have been carried out to verify the effectiveness\nof the proposed algorithm and mathematical model. The results demonstrate that the interpolation algorithm is well within the\ninterpolation requirements of the saddle-shaped weld and ideal feed rate stability....
Flying debris is generated in several situations: when a roof is exposed to a storm, when ice accretes on rotating wind turbines,\nor during inflight aircraft deicing. Four dimensionless parameters play a role in the motion of flying debris. The goal of the\npresent paper is to investigate the relative importance of four dimensionless parameters: the Reynolds number, the Froude number,\nthe Tachikawa number, and the mass moment of inertia parameters. Flying debris trajectories are computed with a fluid-solid\ninteraction model formulated for an incompressible 2D laminar flow. The rigid moving solid effects are modelled in the Navier-\nStokes equations using penalization. A VIC scheme is used to solve the flow equations.The aerodynamic forces and moments are\nused to compute the acceleration and the velocity of the solid. A database of 64 trajectories is built using a two-level full factorial\ndesign for the four factors. The dispersion of the plate position at a given horizontal position decreases with the Froude number.\nMoreover, the Tachikawa number has a significant effect on the median plate position...
In Sweden, the dam-safety guidelines call for an overhaul of many existing bottom outlets. During the opening of an outlet gate,\nunderstanding the transient air-water flowis essential for its safe operation, especially under submerged tailwater conditions.Threedimensional\nCFD simulations are undertaken to examine air-water flow behaviors at both free and submerged outflows. The gate,\nhoisted by wire ropes and powered by AC, opens at a constant speed. A mesh is adapted to follow the gate movement. At the free\noutflow, the CFD simulations and model tests agree well in terms of outlet discharge capacity. Larger air vents lead to more air\nsupply; the increment becomes, however, limited if the vent area is larger than 10m2. At the submerged outflow, a hydraulic jump\nbuilds up in the conduit when the gate reaches approximately 45% of its full opening.The discharge is affected by the tailwater and\nslightly by the flowwith the hydraulic jump. The flow features strong turbulentmixing of air andwater,with build-up and break-up\nof air pockets and collisions of defragmented water bodies. The air demand rate is several times asmuch as required by steady-state\nhydraulic jump with free surface....
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