Fracture of Rolled Homogeneous Steel Armor (Nucleation Threshold Stress).
Abstract
Methods of characterizing the onset of fracture of rolled homogeneous steel armor with stress waves were investigated, and the nucleation threshold stress was determined to be 1.65 GPa. Crack nucleation was associated with the emergence and propagation of 'hair-line' cracks from inclusion-matrix interfaces, and the nucleation threshold stress applies to this condition. To determine this value accurately, the tensile stresses in regions of failure were obtained with the aid of the BFRACT 2 computer subroutine containing the nucleation and growth fracture model, NAG/FRAG. This automatically accounts for the unloading of stress as voids develop and allows one to determine approximately the tensile stress responsible for failure. Crack densities created with plate impacts were plotted versus the corresponding computed maximum tensile stresses, and the curve was extrapolated to the no-damage condition, i.e., the stress below which no cracks should develop. This stress level was equated to the nucleation threshold stress. The nucleation threshold stress that has been determined is a material parameter in the NAG/FRAG analysis of dynamic fracture, and it should, therefore, be useful.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1980
- Accession Number
- ADA081618
Entities
People
- Gerald L. Moss
- Lynn Seaman
Organizations
- Ballistic Research Laboratory