A DCAMM seminar will be presented by
Professor Alan Needleman
Department of Materials Science and Engineering
Texas A&M University, USA
Abstract:
A progressively softening solid is one for which the constitutive relation permits the stress to decrease monotonically to zero. For such a solid, failure in the sense of a complete loss of stress carrying capacity is inevitable. However, it is also possible for localization of deformation to precede failure. The question as to whether localization of deformation or failure occurs first is analyzed for two rate dependent constitutive relations: (i) a Kelvin–Voigt solid and (ii) a viscoplastic solid. A planar block infinite in one direction is subjected to monotonically increasing shear displacements at a fixed rate. Geometry changes are neglected and attention is confined to quasi-static loading conditions. For the Kelvin–Voigt solid, localization precedes failure if there is hardening outside the band and softening inside the band, while failure precedes localization if there is softening both inside and outside the band. For the viscoplastic solid, localization precedes failure when there is softening inside the band regardless of the sign of the hardening outside the band. The scaling with band thickness of the localization time (or strain) and of the dissipation to failure is investigated. Possible implications for grid based modeling
of localization and failure are considered.
Danish pastry, coffee and tea will be served 15 minutes before the seminar starts.
All interested persons are invited.