SINERGI Vol. 27, No. 1, February 2023: 15-22 http://publikasi.mercubuana.ac.id/index.php/sinergi http://doi.org/10.22441/sinergi.2023.1.003 A. Sastranegara et al., Finite element analysis on ballistic impact performance of … 15 Finite Element Analysis on ballistic impact performance of multi-layered bulletproof vest impacted by 9 mm bullet Azhari Sastranegara 1 , Kevin Eka Putra 1 , Edmun Halawa 1 , Nanang Ali Sutisna 1 , Ameen Topa 2 1 Department of Mechanical Engineering, Faculty of Engineering, President University, Indonesia 2 Department of Maritime Technology, Faculty of Ocean Engineering Technology and Informatics, Universiti Malaysia Terengganu, Malaysia Abstract Simulation is one of the most effective ways to reduce the cost and time needed to test the quality of a bulletproof vest. The widely applied method to predict the behavior of the materials is a macro- homogeneous model. However, even though it is low in computational cost, it has some accuracy issues. This work presents finite element analysis with both macro-homogeneous and meso- heterogeneous models to predict the behavior of the Kevlar composites during ballistic impact and qualitatively compares the simulation results with the experimental ones. The simulation reliability was ensured by numerical parameters such as the system energy balance and the limitation of artificial energy. The simulation results showed that the meso-heterogeneous yarn model successfully produced more detailed impact damage than the macro- homogenous model. In addition, the deformation of the Kevlar, the bullet, and the steel plate was close to the experiment results. The result was expected to be used as a consideration in determining the model type for another similar research. Copyright ©2023 Universitas Mercu Buana This is an open access article under the CC BY-NC license Keywords: Ballistic impact test; Macro-homogenous model; Meso-heterogenous model; Numerical analysis; Article History: Received: March 9, 2022 Revised: August 24, 2022 Accepted: September 14, 2022 Published: February 2, 2023 Corresponding Author: Azhari Sastranegara, Mechanical Engineering Department, President University, Indonesia Email: azhari.sastranegara @president.ac.id INTRODUCTION Numerous types of armor have been created throughout the history of body armor, from leather to a vest that protects the torso, which is widely used nowadays. The materials used are also different. During the early wars, most of them were made from metal plates. Although metal plate armor gives enough protection to the wearer, it is considerably heavy, so metal is not compatible with the soldiers' mobility. Nowadays, the primary consideration of body armor is its wearing flexibility and its ability to absorb the impact from the ballistic projectile. Though giving complete protection to the wearer is practically impossible, engineers and scientists made choices in making body armor. The protection of another part of the body armor will be traded off to enhance protection in a specific part [1, 2, 3]. In the process of body armor development, ballistic impact testing is applied to test the ability of the material to absorb the impact from the projectile. The ballistic impact testing shows us the phenomenon of a projectile hitting the targeted vest. However, the testing costs a lot of money and time. Therefore, an accurate numerical analysis is needed to cut the computational cost required [4, 5, 6]. Creating a numerical model of ballistic impact requires the appropriate choices for several features. Model scale and the boundary conditions assumption are crucial, but the most important key point is the choice of the constitutive material models and the related parameters. While the modeling of metal armor is relatively mature, it is not the case for composite fabric like Kevlar. Two prominent techniques have been employed in the literature, each with advantages.