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Aluminum foam sandwich double- pipe structure mechanical behavior of

Author: GuoLiuWei
Tutor: YuJiLin
School: University of Science and Technology of China
Course: Engineering Mechanics
Keywords: Aluminum foam sandwich tube Axial compression Three-point bending Experimental study Numerical Simulation Quasi- static loading Dynamic Impact Energy absorption efficiency Carrying capacity Failure Mode
CLC: TB383.4
Type: PhD thesis
Year: 2010
Downloads: 389
Quote: 1
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Abstract

Thin-walled tube structure as a buffer absorbing component in transportation and aerospace and other fields have a wide range of applications. Walled tube filled with aluminum foam as improved structure, improve the structure and energy absorption capacity, and its lightweight characteristics for reduced energy consumption, reduce air pollution plays an important role. The current structure of aluminum foam filled tubes under axial compression load, the energy absorption efficiency is low, less than an empty tube structure, bending under the action of filling structures were prone to fracture failure, seriously affect the structure of the energy absorption efficiency, and more The actual bending, compression simultaneously fill tube structure behavior under little studied. So this article for the current shortcomings of the fill tube structure, optimize the design of the structure of aluminum foam filled tubes configuration of the new double-barreled sandwich structure in pure axial compression, pressure-point bending and bending under the action of the performance of the experimental system and the numerical simulation, as follows: a) For a more lightweight aluminum foam filled aluminum tube structure sides quasi-static axial compression performance of experimental study, comparing the ATC and the traditional single-tube sandwich structures, to a variety of structures of different deformation modes. The new twin-tube sandwich structure can occur two variants modes sandwich structural stability than single tube. Detailed comparison between the various structural capacity and energy absorption efficiency and other characteristics. The results show that the new twin-tube sandwich structure of the energy absorption efficiency than traditional single-tube filled with aluminum foam and air traffic control structure, and the new structure of tearing modes in the four corners of the energy absorption efficiency than periodic folding patterns. Also studied the inner tube wall thickness pipe sandwich structures for both axial compression performance. Finally, the fill tube structure of aluminum foam core deformation characteristics of aluminum foam, in addition to the high use efficiency is not part of the foam, a more optimal improvements proposed structure: two corners filling pipe structure, and its mode of deformation and associated performance are analyzed and discussed. The deformation of the structure is more stable to improve the energy absorbing efficiency. 2) research is still lacking for aluminum foam sandwich structure of aluminum tube sides conducted a three-point bending properties quasi-static experimental study. ATC contrast, the traditional single-tube aluminum foam sandwich structure of the new structure in the three-point bending under capacity, damage resistance and energy absorption capacity and other characteristics. Dual sandwich structure enhances the structural damage resistance, greatly improving the structure of the energy absorption capacity before failure. The two sides discussed the failure modes of sandwich structures tube, inner tube wall thickness is different dual failure modes of sandwich structures have changed. And on structural span, the inner tube wall thickness and other parameters for both tube bending properties of sandwich structures to carry out some experimental studies. While the inner and outer tube and glued between the role of the core layer are analyzed and discussed. The results showed that the increased role glued bending stiffness of the structure, but the structure while reducing the resistance to bending failure, resulting in reduced energy absorption capacity of the structure. Experimental nature of the material on the wall of a comparative study, carried out simultaneously stainless steel sandwich tube experiments, and the structure of the two materials sandwich tube bending properties were compared. 3) it has not been studied in aluminum foam sandwich pure aluminum double-tube structure and the small-angle oblique axial compression pressure performance of a detailed experimental study. First, double-tube aluminum foam sandwich loaded in pure axial compression deformation characteristics under the inner and outer pipes were discussed, twin-tube inner tube sandwich structures are more likely diamond pattern, but different combinations of both inner and outer tube affects the inner tube deformation pattern. ATC contrast, single-tube aluminum foam sandwich structure, gives dual sandwich structure deformation mechanism explanation. And the optimal combination of twin sandwich structures bearing capacity and energy absorption efficiency is much higher than the traditional single-tube sandwich structures, close to or even exceed the empty pipe structure. Explores the inner tube wall thickness, diameter and wall thickness of the outer tube of the structure and properties of the new sandwich. For baroclinic features, design a set of experiments for baroclinic quasi-static experimental device, and successfully carried out a double-tube aluminum foam sandwich structure in a variety of small-angle oblique loading under pressure in rats. Contrast axial compression, given the ATC, the traditional single-tube filled with aluminum foam and new twin sandwich structures in a variety of small-angle baroclinic mode of deformation under load. In the small-angle oblique pressure load, the structure of aluminum foam filled tubes a special symmetrical upper and lower pairs of semi-flap mixing mode and prone to lateral slip deformation, resulting in a small aluminum foam sandwich structures under load angle baroclinic capacity is very smooth, close to the ideal load bearing structure late, and the average size of the basic capacity unchanged. Experimental results show that the new dual-tube clamped at both ends sandwich structures loaded, its mass energy absorption than the far more efficient than the traditional single-tube sandwich structure, and exceeds the corresponding ATC, while achieving improved capacity size, and enhance the stability and enhance the structure carrying the energy absorption efficiency of the comprehensive goals. And to add perspective on baroclinic structure and properties of a variety of experimental studies carried out. 4) on the new dual-tube aluminum foam sandwich structure under quasi-static three-point bending load performance of the experimental and finite element simulation. Single tube filled with different structures single crack failure, double-barreled sandwich structures in three-point bending cracks appear under special dual failure modes. And new structural damage resistance is much higher than the traditional single-tube sandwich structures, energy absorption capacity has been increased dramatically. Within a reasonable combination of inner and outer tube, the double-barreled sandwich structures Capacity quite smooth, very suitable for energy-absorbing cushioning device. Meanwhile on the span, the inner tube wall thickness, diameter and wall thickness of the outer tube double pipe sandwich structures for three-point bending properties of a certain amount of experimental research. Using the ABAQUS finite element software to build double-barreled sandwich structures under an effective three-point bending model, by analyzing the stress distribution of aluminum foam core gives new structural failure modes specific to the generation mechanism. The lower end of the outer pipe wall and the equivalent plastic strain and maximum tensile strain discussion found maximum tensile strain can be used as the outer tube wall fracture failure of judgment parameters. Explores the double-tube single-tube structure sandwich structure is more resistant to bending failure mechanisms to enhance and give some explanation. Finally an integrated structure bearing capacity and damage resistance, gives optimum overall performance inside and outside pipe diameter ratio. 5) on the new dual-tube aluminum foam sandwich structure in a dynamic three-point bending under the impact of performance drop hammer impact test and finite element simulation. Unlike quasi-static failure modes, dual sandwich structure in the dynamic impact of lower aluminum foam core phenomenon of multiple cracks appear, and more evenly distributed in the middle region, is conducive to aluminum foams absorb more impact energy. And the structure of aluminum foam padding under the impact of low inertia effect is not obvious, the size and capacity of the quasi-static results are very similar. But the dynamic impact of structural damage resistance than the result of a substantial increase in the quasi-static foam filled aluminum structure under the dynamic energy absorption capacity is much higher than the quasi-static results. And compared to the traditional single-tube filled with aluminum foam structure, the new sandwich structural damage resistance and energy absorption efficiency higher capacity also more stable, more suitable as the bearer of the buffer structure. And on the span, the outer tube wall thickness and other factors on the performance of the new structure are discussed. Finally, the finite element model were analyzed under the impact of the new structure peculiar low failure mode generating mechanism, improve the mechanism of resistance to bending failure and quasi-static and dynamic impact of the difference between these causes.

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