**2. Definition and classification of ballistic protection materials**

The development of armaments throughout history had to be accompanied by the development of shields. From ancient times until today, there has been a constant race in the development of weapons and ballistic protection of personnel and vehicles. Since the metal age, the shields have been made of metal, which provided sufficient protection. In the middle of the twentieth century, research has begun on the possible usage of composite materials in protection against projectile penetration. The sudden turn in armor-making technology of that era looked like science fiction. Serial production of composite helmets began in the 1970s in the USA and Great Britain, followed by the production of composite-based armored panels for combat vehicles. Today, modern materials for ballistic protection of humans and vehicles must meet certain strict requirements. Such materials can be defined as materials that must be generally light, cost-effective, low density, high compressive strength, high hardness, durability, and capable of retaining or breaking a projectile penetrator of a certain caliber. Nowadays, ballistic materials can be divided into four basic categories:


As mentioned earlier, metals are the oldest materials used for defensive purposes to cover the body of combat operations. Modern aluminum-based ballistic materials are usually made of 7xxx series aluminum alloy. According to studies, the performance of these alloys can be cured by heat treatment of aging, and sintering can be controlled by particle size. In particular, 7039 aluminum alloys, due to their high strength and ability to absorb energy, are of exceptional importance. These materials are used in combat vehicles as armor material [1–5]. Armor plate of hardened steel has been used for many years to provide protection of objects against impact damage. Commercial representatives of steel used in ballistic vehicle protection are Mars ® 300, high-strength steels, namely AISI 4340 and DIN 100Cr6 [6, 7].

The polymeric-based materials used for reinforcement of matrix intended for ballistic protection of personnel and vehicle can be divided at the para-aramid group (e.g., Kevlar ® and Twaron®), ultrahigh-molecular-weight polyethylene (UHMWPE) (e.g., Spectra®, Dyneema®, and Technora®) and liquid-crystal polymer fibers (e.g., Zylon® and Vectran®) [8]. Polymeric materials are primarily lightweight, but the primary disadvantage of ballistic composites made of polymeric
