Abstract: To evaluate the severity of damage to the human body caused by the blunt bullet or its penetrating through the body armor when the human target wears body armor, a digital model of human body wearing an armor is developed based on real human anatomy data. Then, the process of the bullet penetrating the protected gelatin target is captured by high-speed photography. The evolution data of the instantaneous space cavity inside the gelatin target is obtained. A simplified model of the instantaneous space cavity is established. The Abbreviated Injury Scale (AIS) method is used to evaluate tissue and organ damage. Damage scores of the corresponding parts of the human body under blunt hit and penetrating hit are obtained based on MAIS and NISS damage assessment algorithms, respectively. Besides, mortality rate is predicted. Human susceptibility assessment software is developed to obtain a severity score of damage caused to the human body when a small-caliber bullet bluntly hits and penetrates the body wearing an body armor at different speeds. When a small-caliber bullet hits the human chest with a body armor at 638 m/s, it causes blunt damage; the human injury score is MAIS=3, NISS=27, and the mortality prediction result is 12.88%. When a small-caliber bullet hits at 714 m/s, it penetrates the body armor and directly invades human tissue; the human injury score is MAIS=5, NISS=75, and the mortality prediction result is 97%.

Key words: blunttrauma, penetration, humanvulnerability, bodyarmor, injuryassessment