Investigation of auxetic materials experimentally and using finite element method

Smart materials are designed material that have one or more properties that can be changed in a controlled fashion by tailoring microstructure. There are number of types of smart material and some of them are already commonly used in literature. One of the smart material is auxetic material which have a negative poisson's ratio. When stretched, they become thicker perpendicular to the applied force. Therefore, Auxetic material structures are expected to have superior mechanical properties such as high energy absorption and fracture resistance. Thus they can be useful in medical applications and other industries. Modern technologies require new materials and this new materials require verification of properties. Therefore mechanical property definition and investigation is technologically and theoretically important. Simulation is an effective way to design, predict their mechanical behavior and sizing the auxetic materials. In this thesis, auxetic materials are introduced. In order to obtain auxetic structure, stainless steel plates are tailored in re-entrant shape using femtosecond laser technology. Specimens are designed and sized by CAD software and these models were analyzed by CAE software via finite element modeling (FEM). Mechanical properties of stainless steel sheet before tailoring are determined via tensile testing and obtained parameters are used in simulations. Tensile testing of auxetic sheets are also conducted and then Finite Element results and experimental results are compared and a good match is obtained. Thus, the analysis procedure of auxetic structures are verified for future studies.