%X The mechanical behavior of micro-structured composites has been experimentally and theoretically proven to be strongly dependent on the size of the reinforcement. In other words,
keeping constant the reinforcement volumetric fraction and the mechanical properties of the constituent materials, size effects on the mechanical response are observed by varying the diameter of the inclusion. From the technological point of view, an important example where this
size effect is noticed is represented by superplasticity (Langdon, 1995). Instability phenomena occurring in the microstructure of micro-structured composites are
numerically investigated in this paper. To this aim, an interface constitutive law is proposed to
describe both decohesion and contact at bi-material interfaces. These formulations are
implemented in the FE code FEAP. Then, by applying dimensional analysis (Carpinteri, 1989),
the nondimensional parameters governing the macroscopic response of the composite are
identified. According to this model, transverse debonding with respect to the fiber/particle
direction is simulated and the transition from snap-back instability in case of coarse inclusion
diameters to a stable mechanical response for finer reinforcement is quantified. These results
provide a possible quantitative explanation to the role played by the size of the reinforcement on
the instability phenomena experimentally observed during superplastic deformation.
%D 2005
%L eprints1930
%A Marco Paggi
%A Giorgio Zavarise
%A Alberto Carpinteri
%K Micro-structured composites; Snap-back instability; Superplasticity; Interface debonding; Finite element method.
%B AIMETA 2005 : atti del XVII Congresso dell?Associazione italiana di meccanica teorica e applicata : Firenze, 11-15 settembre 2005
%T Softening and snap-back instability in superplastic deformation
%I Firenze University Press
%O 17th AIMETA Congress of Theoretical and Applied Mechanics, Firenze, Italy, September 11-15, 2005