Forming of closed-cell aluminum foams under thermal loadings: experimental investigation

Metal foams are a new category of materials that in the last decade have been introduced thanks to their good physical and mechanical properties such as high stiffness and low density. Metal foam sheets cannot be formed or bent using the conventional mechanical forming processes because of their low ductility. To overcome this difficulty, a thermal approach was followed in this study, namely, the laser forming process was used to achieve higher bending angles in aluminum closed-cell foam sheets by using the irradiation of a CO 2 laser beam on the surface of the sheets to produce a temperature gradient across the sheet thickness. The effect of the process parameters, including the laser power, scan velocity, beam diameter, and number of the scan passes on the obtainable bending angle, was investigated. Results showed that using concentrated thermal loadings significantly enhanced the formability of the metal foam sheets, compared to applying mechanical bending forces. Finally, an equation was derived to predict the bending angle as a function of the input process parameters.