報(bào)告題目：IS ADIABATIC SHEAR FAILURE REALLY ADIABATIC?

報(bào)告人：Prof. D. Rittel (Faculty of Mechanical Engineering, Technion, Israel)

報(bào)告時(shí)間：2013年5月11日(星期六)上午09:30

報(bào)告地點(diǎn)：爆炸科學(xué)與技術(shù)國(guó)家重點(diǎn)試驗(yàn)室二層會(huì)議室

報(bào)告摘要：

Adiabatic shear failure is a dynamic failure mechanism that results from the formation of a localized narrow band in which the shear strain concentrates and reaches very high values. An early and well accepted analysis of ASB formation relies on the competition between strain-hardening and thermal softening, so that when the latter overcomes the former, the material can no longer harden and fails by shear localization. Therefore, the role of thermally induced strain-softening is viewed as central in ASB formation.

We propose another approach to the phenomenon, based on the dynamically stored energy of cold work, the latter being identified as a key factor for the onset of shear localization. This energy affects and dictates the microstructural re-arrangements (dynamic recrystallization, twinning) occurring during dynamic deformation. In this talk, we will present experimental results on the evolution of the temperature and the microstructure of the dynamically sheared material, and a model describing its evolution. These results will be discussed to propose another physical explanation to dynamic shear localization as a microstructure-related instability.

報(bào)告人簡(jiǎn)介：

D. Rittel holds a PhD in Materials Science (1988) from the Hebrew University of Jerusalem. He spent 2 years as a postdoc at Yale University working on the fracture of tungsten base heavy alloys, followed by 3.5 years at Ecole Polytechnique (France), working on experimental dynamic fracture mechanics. He joined Technion (Mechanical Engineering) in 1994 where he founded the Dynamic Fracture Laboratory.

As of today, D. Rittel holds the Zandman Chair in Experimental Mechanics, heads the Materials Mechanics Center. He is also the Deputy Senior Vice President (Vice Provost) of Technion. D. Rittel was the Clark B. Millikan Visiting Professor in Aeronautics (2007) at Caltech and incumubent of a Catedra de Excellencia at UC3M (Madrid) in 2012.

Throughout the years, D. Rittel has has developed expertise in the many aspects of dynamic failure, including fracture mechanics, constitutive behavior, dynamic failure mechanisms and numerical modeling. D. Rittel is also active in the field of Structural Health Monitoring. He is a Fellow of the Society for Experimental Mechanics (SEM). D. Rittel’s interest is in the thermomechanics and physics of dynamic failure with regard to dynamic fragmentation, fracture, adiabatic shear banding and hysteretic heating. As of today, he has co-authored about 115 journal publications. Dr. Rittel is also Associate Editor of Experimental Mechanics, Mechanics of Materials and the International Journal of Engineering Science.

機(jī)電學(xué)院

2013年5月6日