An Experimental Investigation on the Laser Forming of Aluminum/Epoxy/Glass FMLs

An experimental investigation has been performed to explore the Laser Forming Process (LFP) of Fiber Metal Laminates (FMLs). To achieve this, samples of FMLs were manufactured, comprising two outer layers of cold-rolled aluminum alloy 3105-H14, each with a thickness of 0.3 mm, and a middle layer of epoxy/unidirectional glass fiber composite, with a thickness of 0.2 mm. These samples were fabricated through manual impregnation and subsequently cured under hot pressing. Following this, 27 FML specimens were formed by controlling three key parameters of the LFP: the number of scan passes, scan velocity, and laser power, each varying across three levels. A linear scan path was employed for the laser beam to induce a simple 2D bend. Subsequent measurements were taken to assess the bending angles of each sample after forming, allowing for a comprehensive investigation into the impact of these forming parameters. Evaluation of potential issues, such as aluminum/composite delamination and thermal degradation of the epoxy matrix within the bent area, was carried out using optical as well as scanning electron microscope (SEM) images. Additionally, the effects of the LFP on the bonding strength between the aluminum and composite layers were investigated through peel tests, conducted in accordance with ASTM D1876-61T standards. Following this investigation, it was observed that elevated laser power combined with an increased number of scan passes, alongside a reduced scan speed, resulted in notably significant bent angles of up to 17˚. However, this was accompanied by a corresponding 15% reduction in the delamination peak force, highlighting the intricate trade-offs associated with these forming parameters.