How do woven fibres in a ballistic vest stop or slow a bullet?

Woven ballistic vests function by deforming the projectile and dissipating its kinetic energy across the material's surface area, rather than relying on the rigid imperviousness of traditional metal armour.

When a bullet strikes a textile vest, the following process occurs:

• Deformation: Upon impact with the outermost layers, the bullet is flattened, often taking on a mushroom shape.12
• Energy Dissipation: As the projectile moves through successive layers of tightly woven or laminated fibres—such as nylon or Kevlar—the material absorbs the impact and disperses the energy across a wider area.12
• Entanglement: The bullet becomes entangled within the multiple layers of coarse mesh, preventing penetration.1

While these vests effectively stop handgun and submachine-gun rounds, the wearer may still experience bruising from the force of the impact. For higher-velocity threats, such as rifle rounds, soft vests are often supplemented with advanced ceramics or composite plates to further dissipate energy.12