ConlerenceG CINCINNATI, OHIO/APRIL 30 -MAY 2, 1969 first publicalion rights r e r e w e d by Americon lniliiYte of Aeianoulicr ond Arlronavlicr. 1290 Avenue of Ihe Americol. NFI York. N I l W l 9 Abrtrslctr m o y be publiihed without permission if crcdil i~ given lo avlhor ond lo A I A A . (Price: A I A A M e m b e r $1 00 Nonmember II.SOi Downloaded by PURDUE UNIVERSITY on July 30, 2015 | http://arc.aiaa.org | W AbstractParticle-in-CellB or a n Eulerian? code for a n a l y s i s of the i n i t i a l , e s s e n t i a l l y hydrodynamic processes. The solution i s subsequently transformed to a Lagrangian computational method for treatment of the late-stage, strength-dominated response. The SHPPE program i s described in Reference 8 .Detailed two-dimensional a n a l y s e s have been performed of projectile impacts a t 15.000-20,000 f t / sec into finite laminated targets consistlng of plast i c layers backed by aluminum s u b s t r a t e s . These a n a l y s e s used the SHAPE c o d e , with a comprehens i v e hydrodynamic-elastic-plastic distortional model. 11. Impact Response of Multi-Layered Targets Three solutions are d i s c u s s e d . The f i r s t illustrates phenomena occurring during impacts just under the To illustrate the physical p r o c e s s e s involved in perforation threshold. Fesults showing the time-impact on a multi-layered t a r g e t , a numerical soluresolved development of rear surface bulging a r e tion of s u c h a problem will be used. Figure 1 shows compared with dynamic observations of parallel exthe impact conditions. Additional inputs required for periments. Excellent agreement i s obtained. The the numerical solution a r e the material properties and second and third solutions show conditions leading a failure criterion. For the plastic material, the to perforation. Using a generalized p l a s t i c strain pressure (P) was prescribed by a n equation of s t a t e of criterion, two failure modes a r e identified. Petalling the form P = A(p) + G q e , where A = a l p + a2u2 tends to occur where the plastic front layer of the t a3p3. G is the Gruneisen constant, e i s t h e intertarget i s relatively thick and the failure criterion i s n a l energy per unit volume, q is the relative density, f i r s t exceeded on the back surface near the a x i s . and p is compression. The properties of the plasticPlugging occurs in thinner targets when the failure material were further described by specification of criterion i s f i r s t exceeded a t a n off-axis location on the normal density, yield strength, and s h e a r modu-SHAPE and t h i s failure criterion, predictions c a n be made a s t o whether a given impact will perforate a given complex structure.the plastic-substrate interface. Through use of IUS.
