Types Of Aluminum Foam Research Articles

Biaxial characterization of open-cell aluminum foams from macro to micro responses

This experimental work aimed to understand the effect of a biaxial combined compression-torsion loading complexity on the mechanical properties of two types of aluminum foams having porosities of 85% and 80% and nominal relative densities of 15% and 20%, respectively. In this investigation, open-cell aluminum foam of highly uniform architecture with a spherical porosity was designed and used to investigate the biaxial plastic response. These foams were tested under different quasi-static complex loading paths using a patented rig, called ACTP with different torsional component rates. The key responses to be examined were yield stress, stress plateau, energy absorption capacity, densification strain, micro-hardness, and microstructure. It was revealed that the greater the density of the foam with the higher the loading complexity, the greater the yield strength, the energy absorption capacity, and the micro-hardness. The highest foam strength was thus recorded under the most complicated loading path (i.e., biaxial 60°) for the densest foam (i.e., 80% porosity). This was due to the variation in the cell wall thickness. In addition, the effect of the loading complexity on the microstructure was studied using SEM. The loading complexity of biaxial-45° provides higher particle segregation at the grain boundary and a larger densification strain for the 85% porosity foams.

Small object low-velocity impact damage on hybrid sandwich structures with CFRP face sheets and aluminum foam cores

An important, but insufficiently explored load case for sandwich composites is an impact by a small object. This contribution investigates sandwich panels exposed to such an impact event. The sandwich panels consist of carbon fiber reinforced face sheets and three different core structures, among them two types of aluminum foam and one Nomex honeycomb. The forces during the impact event were obtained by optically recording and analyzing the impactor trajectory. The impact deformation was evaluated using X-Ray computed tomography. An energy balance model, previously used for conventional low-velocity-impact cases, was applied to predict the peak force during impact dependent on the impact velocity, including the described data. The comparison to literature and the coherence of the model to the measured values demonstrated the suitability of the model for this load case. A systematic description of the influences of the sandwich composition on the impact behaviour was identified and qualitatively evaluated.

Torsion Property of the Structure Bonded Aluminum Foam Due to Impact

AbstractAn aluminum foam added with foaming agent, is classified into an open-cell type for heat transfer and a closed-cell type for shock absorption. This study investigates the characteristic on the torsion of aluminum foam for a closed-cell type under impact. The fracture characteristics are investigated through the composite of five types of aluminum foam (the thicknesses of 25, 35, 45, 55 and 65 mm), when applying the torsional moment of impact energy on the junction of a porous structure attached by an adhesive. When applying the impact energy of 100, 200 and 300J, the aluminum foams with thicknesses of 25 mm and 35 mm broke off under all conditions. For the energy over 200J, aluminums thicker than 55 mm continued to be attached. Furthermore, the aluminum specimens with thicknesses of 55 mm and 65 mm that were attached with more than 30% of bonding interface remained, proving that they could maintain bonding interface against impact energy. By comparing the data based on the analysis and test result, an increase in the thickness of specimen leads to the plastic deformation as the stress at the top and bottom of bonding interface moves to the middle by spreading the stress horizontally. Based on this fracture characteristic, this study can provide the data on the destruction and separation of bonding interface and may contribute to the safety design.

Convective heat transfer for fluids passing through aluminum foams

Abstract This paper analyses the experimental findings within heat transfer when heating up air, water and oil streams which are passed through a duct with internal structural packing elements in the form of metal foams. Three types of aluminum foams with different cell sizes, porosity specifications and thermal conductivities were used in the study. The test data were collected and they made it possible to establish the effect of the foam geometry, properties of fluids and flow hydrodynamic conditions on the convective heat transfer process from the heating surface to the fluid flowing by (wetting) that surface. The foam was found to be involved in heat transfer to a limited extent only. Heat is predominantly transferred directly from the duct wall to a fluid, and intensity of convective heat transfer is controlled by the wall effects. The influence of foam structural parameters, like cell size and/or porosity, becomes more clearly apparent under laminar flow conditions.

Simulation on Shock Wave Propagation in Metallic Foams Subjected to Impact Loading

A discretization elastic-plastic material model was used for simulating the shock waves transmission within metallic foams. The density heterogeneity of metallic foams was considered. Several types of aluminum foams are studied on the transmission of displacement and stresses wave under impact loading. The results reveal the characteristics of compressive wave propagation within the metal foams. Under low impact pulses, considerable energy is dissipated during the progressive collapse of foam cells, and then reduces the crush of the objects. When the pulse is high sufficiently, on the fixed end of foam, stress enhancement may take place, where high peak stresses usually occur. The magnitude of the peak stress depends on the relative density of foams, the pulse loading intensity, the pulse loading duration as well as the density homogeneity of foam materials. This research offers valuable insight into the reliability of the metal foams used as vehicles and protective structure.

Measurement and correlation of friction characteristic of flow through foam matrixes

A correlation of friction characteristic was developed based on the measured pressure drop of air through foam matrixes. The pressure drops of seven types of aluminum foams with different porosities and pore densities were measured. The Reynolds number based on the equivalent spherical diameter of the foam ranged from 32.05 to 1289.32. The range of porosity was 0.87–0.958. A empirical equation was developed to correlate the dimensionless pressure drop with the dimensionless flow velocity for all seven types of aluminum foams. The empirical correlation agreed well with experimental data. According to the empirical correlation and the measured data, the pressure drop introduced by foam matrixes was much lower than that by granular matrixes at the same Reynolds number. The relationship between the friction factor and Re of foam matrixes follows the trend of granular matrixes and can be classified into three regimes: Re < 30 , f k ∝ 1 - ε Re ; 30 < Re < 300 , f k = 22 1 - ε Re + 0.22 ; Re > 300 , the value of f k approaches 0.22.