Effect of Geometrical Modeling on Prediction of Laser-Induced Heat Transfer in Metal Foam

Advances in laser forming of metal foam: mechanism, prediction and comparison

“…Experimental investigations confirmed that steep temperature gradients develop in foams [Figure 2(b)], which are similar to the temperature gradients occurring in steel sheets during typical TGM conditions [ Figure 2(a)]. Additionally, it was shown that metal foams yield small Fourier numbers (Fo = Dα / vt 2 ) compared to solids, due to their large sheet thicknesses (Bucher et al, 2016). Hence, from a thermal perspective, metal foam satisfies the prerequisites for the TGM.…”

“…The process window that is applicable to metal foams is a small subset of the sheet metal process window (with the exception of the scan speed), which is not surprising considering that metal foams can only be bent through a single bending mechanism. Table 1 Typical processing conditions used for sheet metal Yao, 2001b, 2001c;Vollertsen, 1993;Scully, 1987;Masubuchi and Jones, 2000;Edwardson et al, 2005b) and metal foam (Bucher et al, 2016(Bucher et al, , 2017Zhang et al, 2015;Roohi et al, 2015;Guglielmotti et al, 2009;Quadrini et al, 2010Quadrini et al, , 2013Santo et al, 2010Santo et al, , 2012 In general, much higher power levels can be used on sheet metals, for various reasons. First, heat can conduct away from the top surface more easily due to the higher thermal conductivity, and overheating occurs less readily.…”

“…While the laser wavelength can have a significant effect on the absorption coefficient (Steen and Mazumder, 2010), the absorption can generally be maintained at a high level by spray-painting the specimens with black graphite paint. Therefore, successful forming experiments can be conducted with many types of lasers, such as continuous-wave Nd:YAG lasers (Bucher et al, 2016), diode lasers (Guglielmotti et al, 2009), as well as pulsed CO 2 lasers (Roohi et al, 2015). Many different types of lasers have equally been used for sheet metal, such as for instance pulsed Nd:YAG lasers (Gollo et al, 2011) or continuous-wave CO 2 lasers (Li and Yao, 2000), again demonstrating the low impact of the laser type on the outcome of the process.…”

“…Due to these unique properties, metal foam excels in many applications such as crash absorbers in cars, as well as structural components in solar power plants and aerospace equipment (Banhart, 2001). Laser forming studies have been performed with different types of metal foams, such as open-cell foams (Quadrini et al, 2010), closed-cell foams (Zhang et al, 2015;Bucher et al, 2016Bucher et al, , 2017, and closed-cell foams with protective skins (Guglielmotti et al, 2009), all reporting that laser forming is capable of bending metal foams up to 45° and beyond. An example for closed-cell aluminium foam is shown in Figure 1.…”

“…Near-net-shape processes, such as powder metallurgy processes (Claar et al, 2000) or 3D printing (Kennedy, 2012), are no valid alternatives either, since the former requires moulds and is limited to small parts with large production volumes, whereas the latter is inherently slow and limited to very small part sizes. Hence, laser forming has a great potential, since it allows for the manufacture of metal foam parts with complex curvatures and arbitrary sizes without tool wear (Bucher et al, 2016(Bucher et al, , 2017. Within the last few years, a lot of progress has been made towards a better understanding of laser forming of metal foams.…”