Dynamic Shear Band Development in Plane Strain Compression of a Bimetallic Body
Interim rept. for Aug 1988-Apr 1991
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We study plane strain thermomechanical deformations of a prismatic viscoplastic body of square cross-section and deformed at a nominal strain-rate of 5000 sec -1. The body has two thin layers placed symmetrically about the horizontal centroidal axis. The layer material differs from that of the body in only the value of the yield stress in a quasistatic simple compression test. The yield stress for the layer material is taken to be either one-fifth of five times that of the matrix material. Three cases, namely, when there is an elliptical void with its major axis aligned along the horizontal centroidal axis or the vertical centroidal axis, but the void center coincides with the center of the cross-section, and when there are two elliptical voids with major axes aligned along the vertical centroidal axis and a void tip abuts the layermatrix interface are studied. The deformations are assumed to be symmetrical about the vertical and horizontal centroidal axes. It is found that in each case shear bands initiate from points on the traction free edges where the matrix layer interfaces intersect them and propagate into the softer material. For the soft layer these bands initially merge into one and propagate horizontally.