WAVE-PROPAGATION IN LAMINATES - A STUDY OF THE NONHOMOGENIZED DYNAMICMETHOD OF CELLS

The nonhomogenized dynamic method of cells (NHDMOC) method uses a trun cated expansion for the particle displacement field: the expansion par ameter is the local cell position vector. We derive and numerically so lve the NHDMOC equations for the first-, second-, and third-order expa nsions, appropriate for modeling a plate-impact experiment. All materi als are linear elastic. The performance of the NHDMOC is tested at eac h order for its ability to resolve the shock wave front as it propagat es through a homogeneous target. The same performance is again tested fora shock propagating through a bilaminate target. We gives only a qu alitative description of the propagating stress wave; the second-order theory performs much better; and the third-order theory gives small r efinements over the second-order theory. In the third-order theory the stress is nearly always continuous across material boundaries, wherea s in first-order, one commonly encounters substantial stress discontin uities. The first-order theory requires a considerable finer computati onal grid to achieve the same satisfactory representation of the wave profile as the third-order theory. Thus very little computational time is saved by using it. The numerical (unphysical) oscillations inheren t in these calculations are largely reduced in the third-order theory, again indicating the rapid convergence of the displacement series. (C ) 1998 Elsevier Science B.V. All rights reserved.