Shock Propagation and Fracture in 6061-T6 Aluminum From Wave Profile Measurements5

Abstract

The use of high-resolution, time-resolved measurements of rear surface velocity in shock loaded 6061-T6 aluminum is discussed as a means of studying spall fracture. The influence of stress pulse shape, material temperature, maximum compressive stress and degree of fracture on free surface motion is presented and correlated with maximum tensile stress at the spall plane. A summary of dynamic properties data (equation of state, elastic wave velocity, stress-strainstrain rate behavior, spall threshold) and a brief discussion on fracture in metals are also presented.iii MANUFACTURING DEVELOPMENT• GENERAL MOTORS CORPORATION

Real-time x-ray diffraction to examine elastic–plastic deformation in shocked lithium fluoride crystals

“…For shock compression along the ͓100͔ direction, impact stresses of 2.4-4.7 GPa ͑3.3%-6.1% density compression͒ were achieved with final stresses ranging from 1.6 to 3.0 GPa ͑2.2%-3.9% density compression͒. The stresses and density compression values cited here were obtained using shock wave data for 6061-T6 Al, 22,23 LiF, 19,24 vitreous carbon, 25 and the measured projectile velocities. Figure 2 shows typical data from a LiF crystal shocked along the ͓111͔ orientation to 3.3 GPa ͑1.7 GPa at the sample/vitreous carbon interface͒.…”

“…Figure 4 shows the results of all experiments performed: changes in the lattice spacing versus the density compression (V 0 /VϪ1) obtained from the Hugoniot data. [22][23][24][25] To relate our results to the compressed state of the unit cell, two extreme ͑or bounding͒ cases were considered. If we assume that unit-cell compression is uniaxial ͑in the direction of shock propagation͒, then the ratio of the lattice spacings, d/d 0 , equals the ratio of specific volumes, V/V 0 .…”

Front Matter

“…I am very conscious of and grateful for their participation in the research efforts [1][2][3][4][5][6][7][8].…”