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Softening and snap-back instability in superplastic deformation

Paggi, Marco and Zavarise, Giorgio and Carpinteri, Alberto Softening and snap-back instability in superplastic deformation. In: AIMETA 2005 : atti del XVII Congresso dell’Associazione italiana di meccanica teorica e applicata : Firenze, 11-15 settembre 2005. Firenze University Press. ISBN 88-8453-313-9 (2005)

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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.

Item Type: Book Section
Additional Information: 17th AIMETA Congress of Theoretical and Applied Mechanics, Firenze, Italy, September 11-15, 2005
Uncontrolled Keywords: Micro-structured composites; Snap-back instability; Superplasticity; Interface debonding; Finite element method.
Subjects: T Technology > TJ Mechanical engineering and machinery
Research Area: Computer Science and Applications
Depositing User: Prof Marco Paggi
Date Deposited: 22 Nov 2013 11:04
Last Modified: 09 Oct 2014 09:20
URI: http://eprints.imtlucca.it/id/eprint/1930

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