Adnan I. O. Zaid
Damages, Hypervelocity Impact, Aircrafts, Space vehicles
Impact conditions involve velocities below the sonic speed, which is normally of the order few hundreds up to thousand m/s, whereas the hypervelocity impact applies for conditions of impact with velocities higher than the acoustic speed of either the impacting object or the impacted target. The velocity at this condition is few thousands m/s and much higher. The effects of hypervelocity impact depend on projectile and target materials, impact velocity, incident angle and the mass and shape of the projectile impacting head. In hypervelocity impact, the projectile velocity exceeds the speed of sound within the target material. The resulting shock wave that propagates across the material is reflected by the surfaces of the target, and reverses its direction of travel. The superimposition of progressing and reflected waves can lead to local stress levels that exceed the material's strength, thus causing cracks and/or the separation of spalls at significant velocities. At low impact velocities, plastic deformation normally prevails. With increasing velocities the projectile will leave a crater in the target. Beyond 4 km/second (depending on the materials), an impact will lead to a complete break-up and melting of the projectile, and an ejection of crater material to a depth of typically two to five times the diameter of the projectile. With decreasing target thickness, the effects range from cratering, via internal cracks, to spall detachment, and finally to plug formation. To avoid the damages caused by the hyper velocity impact phenomenon, it is essential to define and design effective protection measures to protect all structures and their members from the damages particularly aircrafts and space vehicles which are liable to be subjected to such conditions. In this paper, damages caused by this ypes of impact which include: metallurgical changes, scabbing and incipient scabbing, crater formation and fractures are presented and discussed.
Cite this paper
Adnan I. O. Zaid. (2016) Hyper Velocity Impact Phenomenon and the Damages Caused by it to Structural Members. International Journal of Theoretical and Applied Mechanics, 1, 188-193