Investigation of damage modes and associated mechanisms of Kevlar ballistic helmet against bullet impact

Understanding the damage modes and associated mechanisms of the ballistic helmet subjected to bullet impact is vital for advancing helmet design and enhancing protection capabilities. Despite this fact, the damage modes of the ballistic helmets designed corresponding to medium velocity bullet impact (bullet velocity: 426 ± 15 m/s) are not fully explored. This work investigates the microscopic damage assessment of such ballistic helmet in terms of surface damage and internal damage. The ballistic helmet made up of Kevlar® material was used in this work. The stereoscopy test was conducted to observe the surface damage of the ballistic helmet. Further, advanced techniques such as optical microscopy, field emission scanning electron microscopy (FESEM), and computed tomography (CT) tests were used to study the internal damage of the ballistic helmet. The front and side (left) orientations were considered for the aforementioned tests. The results demonstrated that fiber pullout, fiber breakage, matrix compression, matrix cracking, and delamination were the predominant damage modes in the ballistic helmet due to bullet impact. Overall, these findings provide comprehensive insights into various damage modes and underlying mechanisms, paving the way for the design of futuristic ballistic helmets.