Analysis of Explosion Proof Mechanism of Aerogel Explosion Proof Panel
The application of aerogels in explosion-proof and shock-absorbing applications is a major breakthrough in the research of new aerogels materials. Experiments show that the Jero-produced aerogels plate has a good explosion-proof and shock-absorbing function. The 8kg TNT is 450mm from the bottom of the armor , The use of Aerogel Explosion Proof Panel to armor protection. The armor did not penetrate and there was no significant tear in the welded area, reducing the amount of deformation by 14% compared to unprotected materials. The acceleration generated by the explosion in the vehicle body is 98g, which reaches 30.10g after attenuation by the Aerogel Explosion Proof Panel, which is equivalent to the acceleration attenuation of 69.29% and the action time increased by 1.32ms. The result of this experiment laid the experimental basis for the application of aerogels in explosion-proof and vibration-damping applications.
Why this seemingly fragile material compared with steel has the function of explosion-proof and shock-absorbing. This paper attempts to make a qualitative interpretation of the experimental results. Glass fiber and carbon fiber-reinforced Aerogel Explosion Proof Panel belong to porous materials. There is a large number of internal pores, under the action of shock wave material is first compressed dense. Foam deformation generally undergoes three stages: elastic section, yield section, compaction section. Firstly, the wall of the hole is elastically deformed, and some of the impact energy is transformed into elastic energy. At the same time, the air gap is adiabatically compressed and absorbs part of the energy. Then the hole wall undergoes plastic collapse or brittle fracture, transforming part of the impact energy into plasticity, The process is basically over, and then gradually compacted until it is close to the solid material. Once the porous material is completely densified, the shock wave propagation behavior in it is essentially the same as that of the corresponding compact material. At this time, the aerogel colloidal particles collide at high speed and the collision force between colloidal particles increases, which also leads to the destruction of the aerogel structure. The combined effect of the increased transverse tensile stress on the pore walls and the high-velocity collisions between the colloidal particles leads to "comminution" of the aerogel during dynamic compression, indicating that the propagation attenuation effect of shock waves in porous materials depends to a large extent on The energy absorbed or dissipated at all stages of the compacting process.
However, the energy of the shock wave that absorbs and consumes the explosion can be explained by the following reasons. Since the pores in the aerogel are nanoscale, the aerogel permeability is extremely low. During the high-speed explosion, the gas in the aerogel can not escape easily in an instant, and collisions between gas molecules and between gas molecules and the pore walls occur. The molecular mean free path of air molecules (the average distance traveled between one air molecule and another air molecule in succession) was 70 nm, and the average pore size of the aerogel used in the experiment was 16.9 nm. The distance between the wall and the air molecules in the hole is far less than the mean free path of the air molecules, and the specific surface area of the aerogel is very large. Therefore, the collision probability between the air molecules and the hole wall is much higher than the collision probability between air molecules. During high-speed compression, the collisions between the air molecules and the cell walls are more intense than the high-speed collisions between air molecules. The flow resistance caused by the collision between the gas and the pore wall and the collision resistance between the air molecules in the pore can lead to the increase of the pressure in the pore. The air in the nano-scale hole can hardly escape in an instant, resulting in the increase of the pressure in the pore and the energy consumption. The faster the deformation of the material, the more difficult it is for the gas molecules to escape outward. The higher the internal pressure of the pores, the more energy is consumed. Since the stresses in all directions within the stoma are approximately equal, the gas in the aerogel transforms the axial compressive stress into the stress in all directions, ie the stress state in the aerogel changes. Increasing the stress within the aerogel to a certain extent causes the aerogel to explode and cause a loss of energy. The faster the deformation of the material, the higher the pressure in the pores, the more energy is consumed.
In the aerogel explosion process will produce fiber pull out and fiber breakage phenomenon, but also consume a lot of energy, the aerogel toughening effect of the aerogel caused by the explosion requires more internal stress, thus delaying The aerogel explosion makes aerogel need to consume more energy in the explosion, which makes the explosion shock wave energy is consumed in a large amount to play a protective effect of armor.