Fiber metal laminates (FML) as a type of composite materials are obtained from the production of low-thickness metal sheet and resin-impregnated glass, carbon or aramid fabrics in sandwich form using vacuum bagging, hot pressing and autoclave etc. production techniques. FML materials replace traditional non-ferrous metals or laminated composites, especially in the main structural parts of new generation civil aircraft due to their lightness, resistance to impact loading and high fatigue strength. Before production, mechanical (sanding etc.) or chemical (acid etching, anodization, etc.) surface pretreatments are traditionally applied to the metal material surface to improve the interlaminar strength properties between metal and prepreg fabric in FML materials. As an alternative to these surface pretreatment techniques, there are also some studies in which metal material surfaces are pretreated with laser technique in recent years. The ability of the laser to transfer a large amount of energy to the material in a region close to the surface, within the specified limits and in a very short time, provides the opportunity to change the properties of the material locally. The amount of heat transferred by the laser beam to the surface where today's laser technologies come from can be controlled with many different parameters to be different pulse durations, pulse energies and repetition rates. In addition, the response of the materials to the laser wavelength also varies. Therefore, determining the appropriate laser parameters depending on the material is very important to achieve high quality in the final product. In this study, it is aimed to improve the interlaminar strength properties between metal and prepreg fabric by performing surface pretreatments under different laser parameters (such as laser speed, power and frequency) on the surface of metal materials before the production of FML materials. For this purpose, 6061-T4 aluminum sheet plates were treated with a pulsed fiber laser under different laser parameters before the 2/1 configurated FML materials were produced with the hot press technique. In order to determine the effect of laser parameters on the metal/prepreg fabric interlaminar strength of FML materials, three point bending tests were performed on the samples according to the ASTM D790 standard. The flexural strength, flexural modulus and displacement rates of FML samples were determined from the three point bending tests. The obtained results showed that the surface pretreatments using the fiber laser technique applied to 6061-T4 aluminum sheet plates improved the interlaminar strength at metal/prepreg fabric. The flexural strength and flexural modulus values also increased due to the improvement of interlaminar strength at metal/prepreg fabric compared to the untreated FML samples.
Anahtar Kelimeler: Fiber metal laminates, Fiber laser technique, Flexural properties, Metal/Prepreg fabric interface