Özet:

Sandwich composites are optimum material designs that can be created for special applications by combining with different material combinations. Different surface and core materials can be combined with a number of alternative sandwich composite structures. In this study, the sandwich composite material, developed especially for automotive bumper applications, is obtained by combining the core consisting of nylon Polyamide 12 (PA12) polymer material and glass fiber reinforced Polypropylene (GFRPP) lower - upper surfaces. Poisson's ratio, which is an important property of materials; It gives the relationship between the amount of strain of a material in the direction in which the force is applied and the amount of strain in the opposite direction. Poisson's ratio is positive in many materials and negative in some materials. These materials with a negative Poisson ratio are called "oxetic materials". The core with negative Poisson ratio in the produced sandwich composite was produced with Fused Deposition Modeling (FDM), one of the three-dimensional printers. Superior flexing properties are expected thanks to the re-entrant honeycomb geometry. For this purpose, sandwich composite materials with core geometry produced in two different thicknesses were subjected to three-point bending tests. Within the scope of this study, it has been revealed that the distance between the oxetic structures used in sandwich structures is a more important parameter than the thickness of the structure in terms of strength and impact absorption.

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