March 12, 2025 @ 4:00 - 5:00 pm

Pierce Seminar: Prof. Zdeněk Bažant (Northwestern University)

Please join us on Wednesday, March 12, 2025 for the Pierce Seminar at 4 PM in Room 1-131 with Prof. Zdeněk Bažant.
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Please join us on Wednesday, March 12, 2025 for the Pierce Seminar at 4 PM in Room 1-131 with Prof. Zdeněk Bažant.

Abstract Title: Sprain energy and other consequences of the gap test for fracture and damage mechanics

Abstract:

The gap test discovery (PNAS-2020) showed that the crack-parallel stress causes the apparent facture energy to change as much as 2:1 and that the fracture process zone must have a finite width and follow a triaxial softening damage law, with damage localization ilimited by the sprain energy depending on the curvature (or hessian) of the vectorial displacement field. This led to a highly efficient smooth Lagrangian crack band model (slCBM-PNAS-2024) that uses C0-continuity shape functions for both the displacement and their gradients, which are constrained by a second-order Lagrange multiplier tensor. Mesh-refinement at fracture front delivers results independent of mesh rotation. Symmetrizing the displacement gradient shows that the existing strain-gradient damage models, with unresisted rotation gradients, grossly misestimate Mode II and III fractures and Mode I with shear. Strong crack-parallel stress effects must occur in all materials, including atomistically sharp cracks in crystals. Applications: Deep CO2 sequestration, fracking, concrete fracture.

Bio:

Born and educated in Prague (Ph.D. 1963), Bažant joined in 1969 Northwestern faculty, where he has been W.P. Murphy Professor since 1990 and simultaneously McCormick Institute Professor since 2002, and Director of Center for Geomaterials (1981-87). Inducted to NAS, NAE, Am. Acad. of Arts & Sci., Royal Soc. London, Roy. Soc. Canada, national academies of Austria, Japan, Italy-Lincei, Spain, Canada, Czechia., Greece and India. HonMem: ASCE, ASME, ACI, RILEM, CSM. Received Austrian Cross of Honor for Science and Art, 9 honorary doctorates; SES Prager Medal; ASME Medal, Timoshenko, Nadai and Warner Medals; ASCE von Karman, Freudenthal, Newmark, Biot, Mindlin, TY Lin and Croes Medals, Guggenheim Fellow; ARMA Fellow; SEM Murray Medal; ASC Outstanding Res. Award; RILEM L’Hermite Medal; ACI Boase Award, Exner Medal (Austria); Torroja Medal (Madrid). Authored nine books. ASCE established Bažant Medal for failure and damage prevention and ASME Bažant Medal for mechanics. In Czechia: Bažant Prize.