Bifurcation instability in substrate-supported metal layers under biaxial loading
Zheng Jia (University of Maryland), Teng Li (University of Maryland)
Instability in Solids and Structures
Tue 4:20 - 5:40
Barus-Holley 190
Substrate-supported metal layers are being developed as structural elements and functional components in modern technologies, with the promise of enhanced mechanical performance in comparison with freestanding metal layers. Ductile failure of substrate-supported metal layers under in-plane loading often initiates from strain localization, such as the onset of necking instability. Most existing studies on necking limit analysis are based on a bifurcation analysis at the long wavelength limit. In other words, a single diffusive neck is assumed to occur in an infinitely large substrate-supported metal layer. Previous bifurcation analysis of plastic-supported metal films under plane-strain tension reveals that the lowest bifurcation strain corresponds to surface instability (short-wavelength), instead of necking instability (long-wavelength). While for an elastomer-supported metal film under plane-strain tension, the lowest bifurcation strain could correspond to non-uniform deformation at an intermediate wavelength. In other words, multiple necks could appear upon the onset of failure. So far, the bifurcation of substrate-supported metal layers under arbitrary combinations of biaxial in-plane loading conditions remains poorly understood. Here we present a comprehensive all-wavelength study on bifurcation instability of substrate-supported metal layers over the full range of biaxial loading ratio, from 1 for equibiaxial loading, to 0 for plane strain loading, and to -1/2 for uniaxial loading.