Dynamic Mechanical Response And Injury Of Craniocerebral Caused By Rifle Bullet Impacting Bulletproof Plate

In modern times,with the continuous updating of protective equipment,the penetration of bullets into protective equipment is decreasing,however,the large deformation of the back of helmets and other armors has caused increasing attention to people’s secondary injuries.Therefore,it is of great significance and value to study the blunt brain injury and protection caused by the bullet impact on the bulletproof helmet.The main research carried out in this paper is as follows:(1)According to the scan data of head anatomy,a human-like skull model is established.A human brain model is constructed based on the head skin and internal brain tissue are both viscoelastic materials,and the skull material is linear elastic materials.Acceleration and pressure sensors are installed in the model.The acceleration sensor is installed on the skull.The pressure sensor is installed in the intracranial gelatin to prepare for the experiment.(2)Model verification based on the existing head finite element model.The model verification is carried out with reference to the experimental results of foreign cadaver experiments and the simulated human skull model under the combined protection of rifle bullet impact bulletproof board and EVA foam density of 45 kg / m3.In the simulation,the deformation of the back of the bulletproof plate and the change curve and peak value of the skull acceleration are close to the experimental results,and the validity of the finite element model is verified.(3)An experimental study on the mechanical response of the craniocerebral model under the protection of the 5.56 mm rifle bullet impact bulletproof plate.In the experiment,EVA foam materials with different densities,EPP foam materials and no foam pads were used for the research.In the foam-free experiment,the scalp was obviously damaged after the impact,and the peak acceleration and pressure were much greater than those with foam protection.In the foam experiment,at the same foam density,the cranial acceleration and pressure peak gradually decrease along the impact direction;as the EVA foam density increases,the cranial acceleration and intracranial pressure peak both increase;EVA foam material at the same density is used as the The protective effect of the pad is better than that of EPP foam.(4)Using simulation to study the changes of brain dynamics and damage during the impact of a bullet.The rifle projectile impacted the finite element model at a speed of 970m/s in the front,side,and rear;the rifle projectile impacted the front of the finite element model at a velocity of 970m/s and incident angles of 0°,15°,and(5)30°.It is obtained from the simulation that the intracranial pressure is the largest during rear impact,which is more likely to cause craniocerebral injury;the shock wave will propagate in the direction of the impact and gradually attenuate,and it will also propagate in the same tissue;In the finite element model,the cranial stress,the principal strain of the brain and the shear strain are the largest,which is more likely to cause serious craniocerebral injury.Combined with the damage threshold analysis,the craniocerebral injury was not caused during the impact.The article uses the method of combining experiment and simulation to study the dynamic response characteristics and damage research of the craniocerebral under the impact of rifle bullets,which provides a certain guiding value for the design of protective equipment and the mechanism of craniocerebral injury.