Design against slamming loads is the concern of ship designers from the view point of strength for the safety of bow structures. Model test technique using water entry of free-drop bodies into calm water is applied in...
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(纸本)9781479936465
Design against slamming loads is the concern of ship designers from the view point of strength for the safety of bow structures. Model test technique using water entry of free-drop bodies into calm water is applied in this paper to study the hydroelastic impact. One 3D aluminum wedge with dead-rise angle 20 degrees is designed. The stiffened panel on each side of the wedge is made up of 3 longitudinal stiffeners and 2 transverse frames with different sizes of cross sections. The explicit Finite Element Method (FEM) using the Arbitrary Lagrangian Eulerian (ale) algorithm is applied to investigate the hydroelastic impact of this aluminum stiffened panels. The acceleration motion, stress responses on longitudinal stiffeners and transverse frames of the stiffened panels are obtained. The numerical results are validated with the experimental results from drop tests with and without roll angles. This solution shows the capability and accuracy of ale algorithms and its potential to predict the hydroelastic slamming of local structures on ships.
To solve the defects of bottom concave appearing in the extrusion experiments of complex hollow aluminium profiles,a 3D finite element model for simulating steady-state porthole die extrusion process was established b...
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To solve the defects of bottom concave appearing in the extrusion experiments of complex hollow aluminium profiles,a 3D finite element model for simulating steady-state porthole die extrusion process was established based on HyperXtrude software using Arbitrary Lagrangian–Eulerian(ale)*** velocity distribution on the cross-section of the extrudate at the die exit and pressure distribution at different heights in the welding chamber were quantitatively *** obtain an uniformity of metal flow velocity at the die exit,the porthole die structure was optimized by adding baffle *** optimization,maximum displacement in the Y direction at the bottom of profile decreases from 1.1 to 0.15 mm,and the concave defects are remarkably *** research method provides an effective guidance for improving extrusion defects and optimizing the metal flow of complex hollow aluminium profiles during porthole die extrusion.
Single-side- steel-concrete (SSSC) panel and center steel-concrete (CSC) panel, which consists of concrete infill, steel plate, and shear studs, are usually applied as protective structures in the industrial structure...
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Single-side- steel-concrete (SSSC) panel and center steel-concrete (CSC) panel, which consists of concrete infill, steel plate, and shear studs, are usually applied as protective structures in the industrial structures, commercial buildings, and nuclear power plant. In the past, limited research about these types of slabs under blast loads has been studied. In this study, three small-scale RC, SSSC and CSC slabs under contact detonation were tested to obtain the failure modes, mid-span deflection, and dynamic response. Nonlinear 3D finite element models of RC, SSSC, and CSC panels consisting steel plate, concrete infill, and shear connectors were established to assess the blast behaviors using Arbitrary-Lagrange-Eulerian (ale) coupled with Fluid-structure interaction (FSI) algorithm. The accurateness of the numerical models was verified with the experiments by comparison of damage modes and deflection. The results indicated that the failure modes of these slabs were summarized as three types such as type I, type II and type III from both experimental and numerical results. The damaged areas of concrete in SSSC and CSC slabs were larger than that of RC slab. However, the RC slab suffered severe penetration damage with the loss in loading bearing capacity. The experimental and the numerical results demonstrated that the steel plate plays an important role in the blast resistance of SSSC, and CSC slabs under contact explosion, which had better blast resistances compared with the RC slab.
Recently, the microwell has been widely used for cell trapping due to its simple design and enclosed microenvironment for on-chip cell culture and stimulation. In this paper, we investigated the effect of various geom...
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Recently, the microwell has been widely used for cell trapping due to its simple design and enclosed microenvironment for on-chip cell culture and stimulation. In this paper, we investigated the effect of various geometrical factors on microwells for efficient particle analysis. We used the Arbitrary Lagrangian-Eulerian method to calculate the trajectory of particles entering circular and triangular microwells under various geometrical factors, particle size, and flow conditions. Our simulation results show that the W/L = 2 triangular microwell provides the best trapping efficiency due to a stronger recirculation vortex. A smaller particle size or slower flow rate also enhances particle trapping efficiency. To validate simulation results, we flowed 4.5, 6, and 10 mu m diameter polystyrene beads into W/L = 1 circular, W/L = 1 and W/L = 2 triangular microwells under various flow rates. The experimental results agreed well with simulation results, showing that the occupancy of W/L = 2 triangular microwell was sevenfold and twofold higher than W/L = 1 circular and W/L = 1 triangular microwells, respectively. Overall, the above results can provide a useful guideline to design the microwell device for efficient hydrodynamic particle trapping, which can be applied to single cell analysis or rare cell capture.
The focus of this paper is to investigate the damage characteristics and protective structure design of pontoons as an important barrier for the protection of ports. Two types of protective measures of pontoons are in...
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The focus of this paper is to investigate the damage characteristics and protective structure design of pontoons as an important barrier for the protection of ports. Two types of protective measures of pontoons are investigated:filling tanks with water and installing springs in tanks. In this paper, the damage characteristics of two types of pontoon side structures under the action of near-field explosion loads are simulated by using LS-DYNA explicit dynamic analysis software and the ale algorithm. According to the numerical experiment results for filling different volumes of water in the side tanks, the volume of water for the minimum deformation of the shell plate is 100%, and for the first longitudinal bulkhead, it is 30-40%. Moreover, by applying weights to their deformations based on the actual explosion-proof performance requirements of the shell plate and the first longitudinal bulkhead, the pontoon side structure with the best explosion-proof performance can be obtained. The plastic deformation of the pontoon structure equipped with different types of springs is an order of magnitude smaller than that of the ordinary structure and of the pontoon structure filled with a water medium in the positive tanks. The explosive shock wave energy absorbed by the pontoon is effectively reduced by the addition of water or springs to the protective tanks. The minimum energy absorbed by the pontoon structure with water added in the protective tanks is 18.31% of the energy absorbed by the ordinary structure, and the corresponding volume ratio of water added in the protective tanks is 100%. The pontoon structure with springs in the side protection tanks absorbs only 7.2% of the energy absorbed by the ordinary structure. Both new side protection structures have demonstrated excellent explosion-proof performance.
The finite element analysis models of air, concrete slab, soil and explosives, based on numerical calculation, are established. ale algorithm adopted, energy releasing process of explosive material is described by hig...
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The finite element analysis models of air, concrete slab, soil and explosives, based on numerical calculation, are established. ale algorithm adopted, energy releasing process of explosive material is described by high explosive combustion model and JWL state equation, and so attenuation law of soil pressure distribution and motion law of ground displacement field are received. The results would have greatly helped to reflect actual situation and to provide basis for the explosion destroy study on ground surface and safety evaluation.
Using ale algorithm and the JWL state equation for the product of explosive detonation, the numerical simulation of which the shock wave flowed around an obstacle was conducted. The initial development of explosive fi...
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Using ale algorithm and the JWL state equation for the product of explosive detonation, the numerical simulation of which the shock wave flowed around an obstacle was conducted. The initial development of explosive field and the circle-flow behavior, the entire spread course with an obstacle around an explosive source was obtained and the law of shock wave around-flow was analyzed. The research result indicated that the distribution and change of around-flow-field parameters could be fairly described by simulation method in this paper. The simulation result coincided with the law of physics.
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