EFFECTS OF GEOMETRY IN PRESSURE-SHEAR AND NORMAL PLATE IMPACT RECOVERY EXPERIMENTS - 3-DIMENSIONAL FINITE-ELEMENT SIMULATION AND EXPERIMENTAL-OBSERVATION

The minimization of the radial release effects in the recovery configu rations of plate impact experiments is essential for accurate postmort em microstructural investigations. The present study evaluates the res ults of several three-dimensional finite-element simulations involving different plate geometries. The study examines combinations of circul ar, square, and star-shaped plate geometries, with no lateral momentum traps or guard rings. Experiments and simulations are conducted on br ittle specimens. A simple, but fairly successful, combination for the pressure-shear recovery experiment is reported, which makes use of a s ingle square and three circular plates. In the case of the normal impa ct recovery configuration, it is found that the star-shaped flyer in c ombination with the square target and momentum trap gives good results at locations away from the axis of the specimen. Crack patterns obser ved experimentally in the conventional nonrecovery pressure-shear mode , and in recovery pressure-shear and normal impact modes are discussed in relation to the simulation results. (C) 1996 American Institute of Physics.