This is a repository copy of Behaviour of a blast-driven ball bearing embedded in rear detonated cylindrical explosive.

No abstract

This paper presents the unique failure characteristics, such as fragmentation, internal cracks, general deformation and pitting, observed on a SS420C ball bearing from direct blast loading using a cylindrical PE-4 explosive. Axisymmetric simulations were performed to gain insights of the failure mechanisms. While additional work is needed to fully understand all characteristic found, valuable findings have been presented to explain some of the failures.

This paper presents insights into the influence of ball size on the flight characteristics and damage of a ball bearing embedded in a rear detonated cylindrical charge. It includes results from a post-test damage analysis of ball bearings from previously reported experiments. Computational simulations using Ansys Autodyn were used to provide extra information about the velocity variation during flight and the damage sustained by the ball bearings during the blast event. The influence of bearing size (diameter and mass) was investigated using the validated simulation models to extend the dataset beyond the initial experimental work. The peak bearing velocity is influenced by the charge mass to ball bearing mass ratio and the aspect ratio of the charge. Larger ball bearings require extra momentum to accelerate them to higher velocities, but their higher surface area means a greater portion of the explosive charge is involved in transferring kinetic energy to the projectile. Tensile spalling was to be the major damage mechanism within the ball bearings. The charge aspect ratio also influenced the hydrostatic pressure propagation within the ball bearing itself, affecting the location and degree of internal cracking within the bearings. These findings will prove valuable to blast protection engineers considering the effects of embedded projectiles in improvised explosive devices.