The protective principle of bulletproof helmets is mainly based on the material's absorption and dispersion mechanism of impact force. When a helmet is impacted by a bullet or shrapnel, its shell and lining (or pads) work together to disperse and absorb the impact energy.
The casing is usually made of high-strength materials, such as steel plates or titanium alloys. These materials can disperse the impact force to the entire helmet surface, reducing the direct impact of the impact force on the head through the process of elastic deformation and rebound. This dispersion mechanism helps reduce localized pressure on the head, thereby reducing the potential for injury.
Liners (or pads) are usually made from composite armor or polymer materials. When an impact occurs, the lining is able to absorb the impact energy by compressing and deforming. This absorption mechanism further reduces the force of impact on the head and mitigates damage to the brain.
Generally speaking, the protective principle of a bulletproof helmet is to disperse and absorb impact energy through the joint action of the outer shell and lining, thereby reducing damage to the head. This mechanism enables bulletproof helmets to effectively protect personnel's head safety.