BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Leapfrog in Fracture and Damage Mechanics inspired by   Gap Test a
 nd Curvature-Resisting Sprain Energy - Prof Zdenek Bazant 
DTSTART:20230616T130000Z
DTEND:20230616T140000Z
UID:TALK194221@talks.cam.ac.uk
CONTACT:Hilde Hambro
DESCRIPTION:Abstract: For sixty-one years after Ray Clough’s epoch-makin
 g finite element analysis of cracks in Norfolk Dam1\, there has been no co
 mpletely satisfactory computational model for fracture and continuum damag
 e. This is evidenced by recent model comparisons with many distinctive2 fr
 acture tests\, which are those that cannot be fitted closely by very diffe
 rent models and include the size effect\, shear fracture and the new gap t
 est6\,7. The distinctive comparisons demonstrated severe limitations of th
 e phase-field models3\,4\, dismal performance of peridynamics and severe  
  innate inadequacies of the nonlocal models of integral and gradient types
 \, while the crack band model5 (CBM) with microplane M7 constitutive damag
 e law performed well\, though less than perfectly.  Compared to all models
 \, including the nonlocal and gradient ones\, the CBM is the only one that
  has non-problematic boundary conditions. As it transpired\, the CBM perfo
 rmance can be enhanced by introducing an energy\, named the sprain energy 
 Φ\, which augments the strain energy Ψ and characterizes material resist
 ance to the second gradient tensor of curvature of the displacement vector
  field\, named the sprain tensor. This tensor differs from the strain grad
 ient tensor and\, importantly\, includes the gradient of material rotation
  tensor. In FE discretization\, the derivatives of Φ yield self-equilibra
 ted sets of nodal or body sprain forces opposing excessive localization of
  softening damage. Subdividing the material characteristic length into a n
 umber of finite elements allows resolving the homogenized (or smooth) stra
 in distribution across the width of the FE crack band. This leads to the s
 mooth Crack Band Model8 (sCBM) which\, along with M7\, is found to capture
  the big effect of crack parallel stresses on both the fracture energy and
  the crack front width\, as evidenced by the gap test6\,7. Examples of FE 
 fits of distinctive2 data are given.  \n\nReferences:  • 1Ray W. Clough 
 (1962). The stress distribution in Norfolk Dam. Structures and Materials S
 eries 100\, IER Issue 19\, Dept. of Civil Eng.\, Univ. of California Berke
 ley (134 pp.) (contract DA-03-050-Civeng-62-511\, U.S. Army Engineer Distr
 ict\, Little Rock).  • 2Bažant\, Z.P.\, and Nguyen\, Hoang T. (2023)\, 
 ``Proposal of a model index\, MI\, for experimental comparison of fracture
  and damage models." J. of Engrg. Mechanics ASCE\; in press. • 3Bažant\
 , Z.P.\, Nguyen\, H.T. and Abdullah Dönmez\, A.\, 2022\, ``Critical Compa
 rison of Phase-Field\, Peridynamics\, and Crack Band Model M7 in Light of 
 Gap Test and Classical Fracture Tests.” J. of Appl. Mech. 89: 061008\, 1
 -26. • 4Bažant\, Z.P.\, Luo\, Wen\, Chau\, Viet T.\, and Bessa\, M.A. (
 2016). ``Wave dispersion and basic concepts of peridynamics compared to cl
 assical nonlocal models." J. of Applied Mechanics ASME 83 (Nov.) 111004\, 
 1-16. • 5Bažant\, Z.P.\, Le\, J.L. and Salviato\, M.\, 2021\, ``Quasibr
 ittle Fracture Mechanics and Size Effect: A First Course” Oxford UP.  
 • 6Nguyen\, Hoang T.\, Pathirage\, M.\, Cusatis\, G.\, and Bažant\, Z.P
 . (2020). ``Gap test of crack-parallel stress effect on quasibrittle frctu
 re and its consequences." ASME  J. of Applied Mechanics 87 (July)\, 071012
 -1--11. • 7Nguyen\, H.T.\, Dönmez\, A. A.\, Bažant\, Z.P.\, 2021. ``St
 ructural strength scaling law for fracture of plastic-hardening metals and
  testing of fracture properties." Extreme Mechanics Letters 43\, 101141\, 
 1-12. • 8Zhang\, Y.\, and Bažant Z.P.\, 2023\, “Smooth Crack Band Mod
 el (sCBM)—a Computational Paragon Based on Unorthodox Continuum Homogeni
 zation.” J. Appl. Mech.041007.\n\nCollaborators: Yupeng Zhang\, Houlin X
 u\, A. Abdullah Dönmez and Anh Nguyen\nNorthwestern University\, Evanston
 \, IL\, USA\nSeminar Biosketch of Zdenˇek P. Baˇzant April 5\, 2023\nBor
 n and educated in Prague (Ph.D. 1963)\, Baˇzant joined Northwestern in 19
 69\, where he has been W.P.\nMurphy Professor since 1990 and simultaneousl
 y McCormick Institute Professor since 2002\, and Director of Center\nfor C
 oncrete and Geomaterials (1981-87). He was inducted to NAS\, NAE\, Am. Aca
 d. of Arts & Sci.\, Royal Soc.\nLondon\, the national academies of Austria
 \, Japan\, Italy\, Spain\, Canada\, Czech Rep.\, Greece\, India\, Lombardy
  and\nTurin\, Academia Europaea and Eur. Acad. Sci. & Arts. Honorary Membe
 r of: ASCE\, ASME\, ACI\, RILEM. Received\nAustrian Cross of Honor for Sci
 ence and Art I. Class from Pres. of Austria\; 7 honorary doctorates (Pragu
 e\, Karlsruhe\,\nColorado-Boulder\, Milan\, Lyon\, Vienna\, Ohio State)\; 
 U. Minnesota)\; ASME Medal\, ASME Timoshenko\, Nadai and\nWarner Medals\; 
 ASCE von K´arm´an\, Freudenthal\, Newmark\, Biot\, Mindlin\, TY Lin and 
 Croes Medals\, SES Prager\nMedal\; Guggenheim Fellow\; Outstanding Res. Aw
 ard from Am. Soc. for Composites\; RILEM L’Hermite Medal\;\nExner Medal 
 (Austria)\; Torroja Medal (Madrid)\; etc. He authored nine books\, on Scal
 ing of Struct. Strength\, Creep\nin Concrete Str.\, Inelastic Analysis\, F
 racture and Size Effect\, Stability of Structures\, Concrete at High Temp.
 \, Creep\n& Hygrothermal Effects\, Probab. Mech. of Quasibrittle Str.\, an
 d Quasibrittle Fracture Mechanics. H-index: 146\,\n90\,000 cit. (Google). 
 In 2019 Stanford U. weighted and filtered citation survey∗ (see PLoS)\, 
 he was ranked worldwide\nno.1 in CE and no.2 in Engrg. In 2015\, ASCE esta
 blished ZP Baˇzant Medal for Failure and Damage Prevention.\nhttp://cee.n
 orthwestern.edu/people/bazant/\n∗\nhttps://www.mccormick.northwestern.ed
 u/civil-environmental/news-events/news/articles/2018/bazant-ranking.html\n
 \n\n
LOCATION:Department of Engineering - LR6
END:VEVENT
END:VCALENDAR