M.Sc Thesis

M.Sc StudentPtashnik Idan
SubjectExperimental Research of Aluminum Plate Cutting by
Flexible Linear Shaped Charge
DepartmentDepartment of Design and Manufacturing Management
Supervisors PROFESSOR EMERITUS David Durban
PROF. Daniel Rittel
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


This Thesis presents results of an experimental study on dynamic fragmentation of 7050-T7451 aluminum rectangular plates, generated during cutting by a Flexible Linear Shaped Charge (FLSC - with RDX 20gr/ft explosive for the core and lead as the explosive envelope). A large number of tests have been performed over a representative range of plate geometries, with charge placed at a constant stand off and parallel to the long sides of the plates. Weight and length distribution of fragments (carefully collected, washed, dried and sorted out) have been statistically analyzed using available theories, along with a parameter sensitivity assessment. We have identified a critical plate thickness (about 2mm) above which the FLSC jet penetrates only partially through. That figure is supported by an ad-hoc pragmatic analytical model and by cut area detailed fractography.

Extensive data, collected over plate thickness range of 1-3.5mm, reveals that both weight and length of fragments fit very well into the classical Mott distribution. Statistical parameters calculated for Mott formula show little sensitivity to plate length and width. In fact, it can be safely argued that plate thickness is the key parameter which dictates nature of fragments distribution and average characteristics (mass and length). However, number of fragments increases with plate length. A limited comparison with a fractal model, where cumulative fragments number is proportional to power of fragments length, shows reasonable agreement.

This work has been motivated by the increasing threat posed by space debris, hence choice of test specimens made of aluminum which is widely used in aerospace platforms structures. It is hoped that the findings reported in the present research will facilitate efficient control of fragments produced in space systems FLSC separation technology.