Investigation on shock wave mitigation performance of modified polyurea coated helmet

In recent years, traumatic brain injury caused by explosive blast has become the leading cause of death in current military conflicts. However, as for the existing battlefield protection equipment, most of them focus on how to protect against infered injury caused by high-speed shrapnel. Accordingly, there is a lack of systematic research based on shock wave protection. In this work, a new modified polyurea is designed by adding SiO₂ nanoparticles filler firstly. The effects of different proportions of SiO₂ nanoparticles on the thermodynamic, quasi-static and dynamic mechanical properties of matrix are investigated. Further, a test method of material shock wave protection is proposed, which eliminates the influence of boundary and diffraction coupling in the test of protective materials. The protection property of the material under shock wave is tested by the shock tube. Based on the above test results, the full-size shock wave protection test model of human head is developed, and the measurement of overpressure and acceleration peak of several key positions of head is realized. Finally, a new type of shock wave protection helmet is developed, which realizes efficient protection against shock wave. Under quasi-static loading conditions, the yield stress of PU-SiO₂ decreases gradually with the increase of the content of SiO₂ nanoparticles. Under high strain rate conditions, the strain hardening characteristic of PU-SiO₂ increases gradually with the increase of SiO₂ content. In the shock mitigation experiment, the peak overpressure and peak acceleration of shock wave decrease by 32.60 % and 50.90 %, respectively. The peak overpressure decreases again by 11.20 % when the protective material is PU-SiO₂, indicating that the SiO₂ particles can improve the shock mitigation of PU. In the brain protection experiment, the changes in peak overpressure and peak acceleration at the three monitoring sites of the prefrontal lobe, posterior skull, and head reflect the degree of protection of the new material against shock wave.