报告题目：Three-dimensional fracture mechanics：Bridge the gap from laboratory to engineering Structures
报告嘉宾：南京航空航天大学 郭万林 院士
Academician of Chinese Academy of Sciences, chair Professor in mechanics and nanoscience, founder and director of the Key Laboratory of Intelligent Nano Materials and Devices of Ministry of Education and the Institute of Nanoscience of Nanjing University of Aeronautics and Astronautics. He received the National Science Foundation of China for Distinguished Young Scholars in 1996 and the honor of Cheung Kong Scholars in 1999. In 2012, he obtained the National Nature Science Prize of China. He has published 400+ refereed papers in journals such as Nature Nanotech, Nature Comm., Phys. Rev. Lett., Nano Lett., J. Am. Chem. Soc., Adv. Mater., J. Mech. Phys. Solids et al. His current research focuses on three dimensional fatigue fracture and damage tolerance and durability design of structures at high temperature; intelligent nano materials and devices, multiscale physical mechanics, novel conception and technology for efficient energy conversion; Hydrovoltaics and brain-like intelligence.
Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in solids and structures. How to use methods of analytical solid mechanics to determine and evaluate the driving force for propagation of cracks, how to characterize the material's resistance to fracture, and how to apply the material’s properties achieved in laboratory to assess/predict the durability and damage tolerant performance of engineering structures in service life are the main questions to be addressed by fracture mechanics.
We once introduced the out-of-plane constraint factor are the coordinates in the normal plane of the crack front line and z the out-of-plane one) to the asymptotic solution of crack tip fields in three-dimensional (3D) solids and found that Tz dominates the singular term of the crack tip fields together with K in linear elastic solids and J in power law hardening materials, leading to the K-Tz and J-Tz two-parameter theory. We have also developed the J-Tz solution to three-parameter J-Tz-QT solutions to consider both the in-plane and out-of-plane constraints, and recently to C*-Tz-Q* solution for power law creeping solids as well as propagating cracks. Here we will present our recent advances in developing the two- and three-parameter theories and their applications to fatigue and creep fracture assessments of typical engineering structures, with the following critical issues being addressed.
1) From 2D fracture mechanics to 3D fracture mechanics,
2) From tensile to mixed mode loadings,
3) From static/toughness to fatigue/durability,
4) From ambient to high temperature environments,
5) From empirical design to predictive design,
6) From continuum methodology to multiscale simulations.