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![Comparison of model to Lee and Kim [9].](publication/282833965/figure/fig3/AS:1086785794899996@1636121333475/Comparison-of-model-to-Lee-and-Kim-9_Q320.jpg)
A finite element simulation of the compaction and springback of an aluminum-based powder metallurgy alloy (Alumix 321) was developed and validated using the LS-DYNA hydrocode. The present work aims to directly address the current scarcity of modeling works on this popular alloy system. The Alumix 321 constitutive material parameters are presented....
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Citations
... Geological Cap model parameters for Al 6061 powder[36,25]. ...
In this work, the effect of discharge energy on the densification, mechanical properties, and microstructure of Al 6061 alloy compacted by electromagnetic axial compaction was studied. At 19 kJ, 22 kJ, and 25 kJ discharge energies Al 6061 powder was compacted. The aforementioned characteristics of Al 6061 compacts enhanced with discharge energy. Quantitatively, at the maximum discharge energy, relative density reached 96.7% and microhardness 44.78 VHN as well as compressive strength of 147.34 MPa. Optical microscopy results showed pores fraction decreases with increase in discharge energy with lowest porosity of 0.47%. At various time steps, LS-Dyna multi-physics modelling predicts powder body deformation, velocity, and stress-strain distribution which agreed well with experimental results. Significant visualisation by strongly coupled FEM-BEM showed that the top layer of the powder body deformed higher than the bottom layer according to displacement contours. Also, the thermal evolution of the driver plate can be successfully captured.
... Geological Cap model parameters for Al 6061 powder[36,25]. ...
In this work, the effect of discharge energy on the densification, mechanical properties, and microstructure of Al 6061 alloy compacted by electromagnetic axial compaction was studied. At 19 kJ, 22 kJ, and 25 kJ discharge energies Al 6061 powder was compacted. The aforementioned characteristics of Al 6061 compacts enhanced with discharge energy. Quantitatively, at the maximum discharge energy, relative density reached 96.7% and microhardness 44.78 VHN as well as compressive strength of 147.34 MPa. Optical microscopy results showed pores fraction decreases with increase in discharge energy with lowest porosity of 0.47%. At various time steps, LS-Dyna multi-physics modelling predicts powder body deformation, velocity, and stress-strain distribution which agreed well with experimental results. Significant visualisation by strongly coupled FEM-BEM showed that the top layer of the powder body deformed higher than the bottom layer according to displacement contours. Also, the thermal evolution of the driver plate can be successfully captured.
... Selig et al. [6] developed Ls-Dyna hydrocode to perform Alumix 321 powder compaction and spring back simulation. Experimental results from optical densitometry analysis agreed with the simulation results. ...
... All the structural parts have meshed with eight-node quad elements in the Ls-Dyna analysis. The Coulomb friction constant value of 0.25 is applied between all the contacting surfaces [6]. ...
In this article, Finite element modelling is described to simulate aluminium powder’s electromagnetic radial powder compaction process. Electromagnetic powder compaction technique is considered a high strain and high-speed powder forming technique in which solenoid coil with uniformly tapered step field shaper is used as forming tool for powder compaction process. In this process, the packing tube that holds the powder acts as a driving medium for the momentum transfer. During experiments, aluminium powder is kept in an electrically conductive driver tube material (in this study, Al 6063 tube). This process utilizes the Lorentz forces for compacting powder to give the required strength for the powder metallurgy component. This paper mainly develops a non-coupled finite element model to simulate the aluminium powder’s electromagnetic powder compaction process. A versatile software Ansys Maxwell was used to analyze the intensities of the distribution of the electromagnetic fields during the electromagnetic forming process. The current curve obtained in the experiment is used as input loading conditions for analyzing electromagnetic fields. After that, for structural analysis of the powder compaction process, Ls-Dyna explicit software is used. The Geologic cap model was established in Ls-Dyna Multiphysics software for modelling powder deformation behaviour. The Johnson-Cook strength model was used to describe the packing tube’s deformation. The FEM analysis helped predict the results of the final shape and size of electromagnetic powder compaction. The developed simulation model has been validated with a series of experiments resulting from the compaction of aluminium powder.
... The powder is modelled using the Geologic cap hardening material model, which can also be represented with the Drucker-Prager cap model. The material model parameters for Al 6061 power are derived from experimental tri-axial data studied by Lee et al. [12]. This work uses the same material model constants to simulate the Al 6061 powder for EM powder compaction. ...
... Chemical Composition of Al 6063 tube material. Geologic Cap model parameters for Al 6061 Electromagnetic powder compaction[12]. ...
Electromagnetic powder compaction is considered a high strain and high-speed powder forming technique. The method uses the Lorentz forces for compacting powder to obtain near net shape and high strength compact through the PM route. This process can be classified as a contactless powder compaction technique since no physical punch is used to form powder for compaction. All kinds of materials, irrespective of the powder particle's hardness and size distribution, can be compacted using this technique. Few materials are tough to compact due to their higher hardness as well the frictional forces are very high during the compaction of Nanosized metallic powder. These barriers can be easily overcome by using high velocity and energy, such as the electromagnetic forming technique. In this paper, a non-coupled finite element model is developed to simulate the electromagnetic powder compaction process of pure Aluminium. ANSYS-Maxwell is used to investigate the electromagnetic field distribution in electromagnetic powder compaction tooling setup. The Geologic Cap model was used in the LS-Dyna Multi-physics solver to describe powder deformation during the compaction process. The Johnson-Cook plasticity model describes the deformation behaviour of the Al 6063 packing tube. Finally, the developed simulation model is validated with experimental results of aluminium powder compacts at 12 kV and 13 kV. The powder compaction experiments were carried out using a 40 kJ capacity electromagnetic forming machine. It found that the simulation results agreed with experimental data results. The comparison is made between the final diameters of the compact obtained through simulation and experiments.
... Geological Cap model parameters for Al 6061 powder[36,25]. ...
The present research's objective is to investigate the electromagnetic radial powder compaction process and its effect on the densification, microstructure and mechanical properties of the Al 6061 alloy powder. Cylindrical product has been prepared from Al 6061 powder using the electromagnetic powder compaction method. In this method, electromagnetic force shrinks the packing tube and utilises the deformation of the tube to compact the Al 6061 powder. The electromagnetic forces were generated between the field shaper's inner cylindrical surface and the outer surface of the packing tube when a high voltage current is flowing through the solenoid coil. In this study, the Al 6061 powder is compacted at various discharge voltages such as 13 kV, 14 kV, 15 kV and 16 kV using a 20 kV and 40 kJ capacity electromagnetic forming machine. Sintering is performed on the compacted samples at 620 °C for 1 h in an N2 tubular furnace. The simulation was carried out using loosely coupled multi-physics software, and simulated results were validated with the experimental results. Ansys Maxwell is used to analyse the electromagnetic field, and Ls-Dyna is used for structural analysis. To describe the deformation behaviour of the packing tube, the Cowper –Symonds model was used. The deformation in the compact and stress-strain variation was analysed using simulation results and experimental results. The effect of field shaper on powder compaction is investigated using the magnetic field analysis of the Ansys Maxwell results. The velocity of the packing tube is analysed for various input discharge voltages. The Vickers micro-hardness of electromagnetic powder compacted samples increases with compaction voltage. Finally, the results predicted by numerical simulation were verified with experimental results and found in good agreement.
... This assumption is obviously not correct as elasticity modulus varies with relative density. However, it has been shown that the Poisson's ratio is weakly dependent on the relative density [33,38,39]. Only a small number of researchers [10,33,39] took dependency of E to hydrostatic pressure into account. ...
... However, it has been shown that the Poisson's ratio is weakly dependent on the relative density [33,38,39]. Only a small number of researchers [10,33,39] took dependency of E to hydrostatic pressure into account. Coube and Riedel [33] used the following relation for E in the modeling of metal powder compaction: ...
... υ is the Poisson's ratio, E 0 is modulus after complete unloading, and A and n are material parameters. Selig [39] assumed a linear relation between E and the relative density in the compaction modeling of Al powders. For current study also, the Young's modulus is defined as a function of powder relative density. ...
Determination of the parameters of modified Drucker–Prager Cap (DPC) constitutive model for Al7075 powder is investigated in this work. The parameters are normally identified by experiment which is time consuming, tedious and expensive. In this study, the constants of DPC model are identified by conducting only a simple uniaxial powder compaction test, using finite element (FE) simulations in ABAQUS/standard, and utilizing artificial neural networks (ANN). The relation between the Young’s modulus (E) and relative density of the powder was incorporated in ABAQUS code using a USDFLD user-defined subroutine. In the proposed approach, the neural networks are trained to predict the DPC parameters in a way to minimize the differences between experimental and FE curves of uniaxial powder compaction. The input parameters of the ANN were features of uniaxial powder compaction load–displacement curve. A reasonable agreement was observed between the experimental and numerical load–displacement curves of the powder compaction for the DPC parameters predicted by ANN. Moreover, the accuracy of this DPC model was verified again in compaction of a bush-type sample.
... Moreover, the central regions of the compact including region 1 consolidate uniformly. Selig [42] used a Drucker-Prager Cap model to study the cold compaction of Al powders. Lee [43] simulated densification behavior of Al powders using a hyperbolic Cap model. ...
In this study, a method called microwave-assisted hot compaction process was used to fabricate bulk Al sample. After the cold pressing process of Al powders, the green compact was hot-pressed in a microwave-assisted hot press apparatus at 400 °C under the pressure of 50 MPa. Moreover, numerical simulation of microwave-assisted hot compaction process was performed using 3D finite element method. Comparison between numerical and experimental results was also investigated. The microstructure, pore distribution, and surface topography of the sample were observed by scanning electron and atomic force microscopes. The density of the bulk sample was measured by Archimedes technique. Finally, nanoindentation test was carried out to measure hardness and elastic modulus. The results showed that the sample was heated uniformly using microwave heating process. Despite the uniform heating, the top corner regions of sample exhibited higher density as compared to the bottom corner regions. However, the central regions of the sample consolidate uniformly. Also, the top corners of the sample with more densification showed an improvement in the mechanical properties of the sample.
... The material composition of Alumix 321 is given in Table 6. This material was selected as base matrix because it is a well understood and documented powder (Selig, 2012;Selig & Doman, 2011a, 2011b. The cavity shell material was a sphere made of Al3003, the material properties are shown in Table 6. ...
... As such, as the threshold increases, more shades of grey are counted, and thus, a lower relative density value would be calculated. This phenomenon is shown in Figure 20, where the image on the left is analyzed with a threshold of 75 and the one on the right is analyzed with a threshold of 150 (Selig, 2012). The relative density of the image on the left image is 86.9% (threshold of 75) while the image on the right has a relative density of 79.6% (threshold of 150). ...
... The upper/lower punches were assumed to be rigid bodies and made of steel. The powder employed a material model developed by Selig (2012) which accounts for the pressure-densification nature of metal powders. The internal structure was modeled using a simplified Johnson-Cook material model for aluminum attained from the U.S. Department of Transportation (Kay, 2003). ...
Powder compacting is a widely used process for both metallurgy and pharmaceutical production. The mathematical simulation of the powder compaction process is a promising tool for its study. The compacting of WC/Co powder by a punch in a cylindrical die is simulated in this work. The use of the Drucker-Prager Cap constitutive model is made. Results on stress distribution and volume plastic deformation during compaction are obtained. Relative density distribution in the powder compact can also be estimated from volume plastic strain. The severe influence of frictional contact between powder and die wall on the results is noted.
This work evaluates the deformation behaviour, at warm working temperatures, of green particle-reinforced aluminium composites produced by powder blending in a high-energy ball mill. The work focuses on metal matrix composites (MMCs) based on the 2124-Al alloy, reinforced with 10 or 15 vol.% SiC and metal matrix nanocomposites (MMNCs) based on the 2124-Al alloy, reinforced with 5 or 10 vol.% Al2O3. Three batches for each powder were blended and powder properties such as particle size distribution (PSD) and shape were consistent after blending. It was observed that a more uniform distribution of the reinforcement phase in the aluminium alloy matrix was achieved in 2124-Al/Al2O3 than in 2124-Al/SiC composites. The powders (unreinforced 2124-Al and blended) were initially over-aged at 350°C for 2 hours to reverse any natural ageing that may have occurred prior to use. The over-ageing was incorporated to improve compressibility of the powders with the aim of achieving green compacts with higher integrity. Uniaxial compression tests performed at ambient temperature on a Gleeble® 3500 thermomechanical simulator were unsuccessful as the green compacts fragmented. Engineering stress-strain curves showed that green compacts of unreinforced 2124-Al, 10%SiC MMC and 5%Al2O3 MMNC deformed in a similar manner at ambient temperature and had the same compressive fracture stress of approximately 170 MPa. When the deformation temperature was increased from ambient to warm working temperatures (170-280°C) it was observed that electrical resistance heating (the heating mode of the Gleeble®) of unreinforced Al alloy, MMC and MMNC green compacts did not occur. This was attributed to the high electrical conductivity of aluminium, which resulted in poor heat generation due to the low electrical resistance in the samples. It was presumed that the small sample size (d=8 mm, h=12 mm) also caused rapid heat loss. After further experimentation, the green compacts were heated successfully by insulating the samples to retain heat. It was found that at 280°C, increasing the soaking time from 6 to 20 minutes decreased flow stress and improved plastic flow in the 2124-Al/10%SiC green compact. © 2016 The Southern African Institute of Mining and Metallurgy.
