טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentNeuberger Avidov
SubjectScaling the Structural Response of an Armored Vehicle to a
Close-Range Large Explosion
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Daniel Rittel


Abstract

The blast response of structures has been extensively investigated. However, two points have remained unexplored. The first concerns close-range large explosions, which are becoming an increasing threat to armored vehicles. The second open point is that of the scaling down of the problem, or in other words, can we devise simple, yet reliable, procedures to mimic close-range, large explosions on scaled-down models?

This research focuses on scaling the structural response of clamped circular plates that are subjected to close-range, large spherical blast loadings (both air-blast and buried charges). The clamped circular plates are a generic structure that represents an armored vehicle. Full-scale experiments involving authentic size geometries and charges are quite involved and costly, both in terms of preparation and measurements. For these reasons, scaled-down experiments are highly desirable. However, the validity of such experiments remains to be firmly established, and this is the main objective of this research. Here, similarity is obtained by using replica scaling for all geometrical parameters, while the blast effect is scaled by using the Hopkinson scaling law. We also consider the overall effect of the material’s strain rate sensitivity and variability of material properties with plate thickness on the response of the scaled model.

In the case of buried charges, both the depth of burial and nature of the soil have a significant effect on the energy which is directed towards the target by funneling and magnifying it upwards. This research also addresses the effect of flush burial of the spherical charge in dry sea sand on the target’s dynamic response compared to a target loaded by similar air-blast energy.

This study presents numerical and experimental results from a series of controlled explosion experiments, for both flush buried and air detonated charges, including a comparison of these two cases. The experimental and numerical results agree quite well, so that the main conclusion of this study is that scaling can be successfully applied to investigate the structural response of a clamped plate subjected to a violent explosion. However, one should know the limitations of this procedure and the distortions caused by the differences of material properties at the different scales.