Investigation of behavior of thermoplastic sandwich structures with auxetic core geometries produced by 3-dimensional additive manufacturing method under static and dynamic loads

Lightweight sandwich structures are used extensively in various application fields, especially automotive, marine and aviation. The main reasons for the rapid spread are that these structures have high specific flexural stiffness and energy absorption capacity. Sandwich structures mainly consist of core and face sheets. The main elements that give selectivity and variability to the structure are core structures. The core structures, consist of porous materials and structures, developed as a result of numerous analytical and experimental studies for many different purposes and applications. These structures, which have different advantages compared to each other, are determined according to the features desired from the usage areas. Many known engineering materials have a positive poisson's ratio, which is described as traditional. Recently, with the advances in additive manufacturing methods, new structures and materials with negative poisson ratio (NPO), which do not have traditional behavior, have begun to emerge. These new materials, called auxetic materials or structures, are also known as metamaterials. Thanks to the NPO mechanism, these structures can have superior properties, especially in energy damping and durability. In this study, two traditional and three auxetic core geometry sandwich structures were produced with additive manufacturing method. The energy damping abilities, strengths and damage mechanisms of the structures produced from fully recyclable bioplastic