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In this investigation a computational model has been developed which includes heat and mass transfer as well as effects of backpressure, and mould wall friction for the simulation of incompressible flow with free surfaces in mould cavity filling. The simulation of flow with free surfaces is based on the SOLA-VOF numerical algorithm, utilizing the finite difference method. The solid and free boundary conditions have been modified and a new algorithm has been developed to calculate the effect of cavity pressure and wallslip ratio, during mould filling. In this algorithm, the effect of wall-slip ratio on filling pattern has been modeled with an experimental function. In order to verify the computational results, the casting of an aluminum alloy within a transparent mould has been carried out and the mould erosion at different times has been recorded. A series each moulds with different grain fineness number were used to take into account the effect of surface roughness on flow pattern, the amount of erosion and the impact of the molten metal on the sand mould, using a photograph technique. The comparison between the experimental and the simulation results of sequence filling of a sand casting shows a good level of consistency that confirms the accuracy of the model for predicting erosion of the mould material.

SUMMARYA new mathematical model has been developed to simulate mould ÿlling in the lost foam casting process, using the ÿnite di erence method. The simulation of molten ow and track of free surfaces is based on the SOLA-VOF numerical technique. An algorithm was developed to calculate the gas pressure of the evaporated foam during the mould ÿlling. The e ect of backpressure on the ÿlling behaviour was modelled with an experimental function by adding three-dimensions 3DVOF functions. In order to verify the computational results, a thin grey iron plate was poured into a transparent mould. Cavity ÿlling, foam depolymerization and gap formation were recorded with a 16mm high-speed camera. A good agreement was achieved for simulation results of ÿlling sequences with those from experiments.

This article investigates the quasi-static compressive behavior and the drop weight impact tests during the crashing of energy-absorbing structures such as aluminum foam-filled tubes. The closed-cell Al and A356 Alloy foams were cast and, after cutting, inserted into the Al thin wall tube as axial fillers of single-, double- and quad-layer structures. Then, the specific energy absorption (SEA), complementary energy (CE), normalized energy (NE), and specific normalized energy (SNE) are calculated based on static and dynamic test results under uniaxial loading. In this new method, values of NE and SNE are always between 0 and 1. Results show that the SEA-strain curves obtained from crashing the foam-filled tubes were linear and overlapping under static and dynamic loading. However, NE curves for dynamic tests were cyclic and in the static tests were asymptotic non-linear, and utterly separable. Results indicated that the SNE for Al, A356 single layer, Al-A356 double-, and Al-A356-Al-A356 quad-layer foam-filled tubes during dynamic tests were 0.25, 0.29, 0.31, and 0.31, while for the static tests, 0.14,0.15, 0.17, and 0.14 were recorded. It was found that CE and NE energies were better than the SEA energy for recognizing plastic deformation and crushing behavior.

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SUMMARYIn this study, a computational model has been developed for determination of metallostatic pressure on the heat transfer coefficient, resistance of metal-mold interface and solidification time for solving of heat transfer equations. The simulation of interface resistance is based on the zero thickness element (ZTE), using the finite element method (FEM). The solid boundary conditions, including contact resistance have been modified by pressure gradient in each ZTE. The pressure gradient has been imposed by an experimental function, which obtained based on experimental data. In order to verify the computational results, an A356 Aluminium alloy has been poured into a permanent mold and temperature of interface was measured by data acquisition system. The comparison between the experimental and the simulation results during solidification process shows a good agreement that confirms the accuracy of the model in order to simulate the effect of interface resistance on the solidification time.

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