The aim of this study is to investigate the dynamic mechanical properties of composite materials reinforced by mineral experimentally. Graphene and huntite minerals were added to epoxy resin at different weight ratios (wt.-%) as 0.5 weight percent, 1 weight percent and 3 weight percent, to examine the effect of mineral types and percentages on the resulting dynamic mechanical properties. In addition, the effect of non-layered huntite unlike graphene, with a nano-sized grain structure, was investigated. Thus, glass transition temperature (Tg), storage modulus (E’), loss modulus (E”) and damping ratio (tan δ) values were determined and compared. Moreover, a tensile test was performed in order to explain the relation between stress and strain. It was seen that adding different minerals caused different results according to types and proportions. In general, adding minerals to the pure resin increased the storage modulus and loss modulus, whereas the damping ratio (tan δ) decreased compared to the pure resin.

The transformation of an object from its original shape under the influence of various internal and external forces is called deformation. Auxetic deformation, unlike conventional deformation, can occur irregularly on the object. For this reason, the Poisson’s ratio values of the auxetic materials vary according to the measurement points on the auxetic specimen and different elongation amounts. Although there is no standard experimental method for determining the Poisson’s ratio, which shows the degree of auxeticity in the literature, different methods such as taking measurements from different measurement areas and considering different cell numbers have been used to determine the Poisson’s ratio. However, the calculated Poisson’s ratio represents only the measured points. In this study, the Poisson’s ratios of three different cell structures that are tetra-chiral, antitetra-chiral, and hexa-chiral structures were determined numerically and experimentally at varying elongation amounts of 1mm, 2mm, and 3mm. Auxetic plates with three different chiral structures were produced from PLA material with a three-dimensional printer for experimental analysis. A Digimizer image processing program was used to obtain the Poisson’s ratio in experimental measurements. The specimen was photographed by the device at certain elongations, and the elongation values at the measurement points were obtained through the program. The values of the experimentally established Poisson’s ratio were also calculated numerically using the ANSYS finite element program at varying deformation rates. Thus, the Poisson’s ratios for the changing cell structure, and elongation amount were obtained comparatively and their changes were revealed to establish a measurement standard.

Composite materials are materials formed by combining two or more components that are macro-dimensionally different from each other. These different materials that make up the structure, age depending on time and environmental conditions like all materials. This aging can occur naturally over time from external factors, or it can be artificially aged by placing the specimen in a certain temperature environment. It is possible to observe some changes in mechanical properties due to the aging process. However, studies involving natural aging are not diverse to determine changed mechanical properties. Since long periods are needed for natural aging, artificial aging under controlled conditions with the help of the special equipment is frequently seen in studies. The aim of this study is to determine the effect of natural aging on elastic constants and the buckling response of laminated composite materials. In order to determine elastic constants of aged and unaged plates, tension and in-plane shear tests are performed on [0]8 and [90]8 E/glass-epoxy composites, respectively. In addition, the effect of natural aging on the buckling load for rectangular plates of various length/thickness ratios, and ply orientation is examined for clamped-clamped boundary conditions. For this purpose, numerical and experimental studies are conducted on aged and unaged specimens. Buckling analysis of the laminated composites is performed by using finite element analysis software ANSYS. Comparisons were made between the test results and predictions from finite element analysis. Good agreement is obtained between the numerical and experimental results. The results show that the long-term natural aging process decreases the elastic constants and buckling load of the composite materials.