Influence of Fatigue Damage on the Response of α-Fe to 1D Shock and Spall Loading

Author(s):

Scott A. Turnage and Joseph Indeck

Abstract:

The dynamic strengths of certain materials such as alpha (α)-iron (Fe) have been well studied, but while the damage imparted by shock and spall loading in pristine α-Fe is well known, hardly any effort has probed the influence of existing damage on the dynamic mechanical performance of the material. Here, α-Fe is subjected to varying degrees of fatigue loading resulting in differing levels of fatigue damage. Materials are then loaded under shock and spall with compressive shock stresses ranging from 6 to 16 GPa. The influence of voids formed by fatigue damage are discussed in terms of the influence on the Hugoniot elastic limit (HEL), phase transformation stress, and spall stress. Fatigue damage is shown to reduce the HEL but exhibits little influence on the phase transformation stress. Fatigue damage noticeably affects the spall strength by influencing the critical peak shock stress at which spall strength transitions from decreasing with increasing peak shock stress to increasing with increasing peak shock stress.