- Dynamic crack propagation in single crystal brittle solids
- Interaction of dynamic crack and other defects in single crystal brittle solids
- Fracture and chaos
- Mechanical behavior of materials in the submicron/nano scale
- Mechanical behavior of multilayered multimaterial systems
- Ballistic damage mechanisms in ceramics
פרופ' דב שרמן
CURRENT RESEARCH INTERESTS
After completing his doctorate in Mechanical Engineering, Sherman returned to Israel and joined the Nuclear Research Center-Negev and served there as a researcher. In 1994 he joined the Department of Materials Science & Engineering at the Technion. He is a member of the Israel Union for Theoretical and Applied Mechanics, the American Ceramic Society, the Materials Research Society and Dymat Association.
The main subjects of our research are fracture processes and mechanisms in ceramics in form of single-crystalline, polycrystalline and in laminate architecture, characterization of the fracture energy of interfaces, and related topics.
The dynamical behavior of a rapid crack in a single crystal brittle solid was investigated lately. Wide thin strips like specimens were fractured under three point bending, where the low energy cleavage plane was inclined to the KI plane. As a result, large sets of surface perturbations were generated. The spatial perturbations were studied using non-linear dynamical analysis. It was found that the crack profile can be described as a chaotic deterministic function, and that the governing
equation of motion in the analyzed region can be described by a set of differential equations with a minimum of seven independent dynamical variables.
A special material architecture, that of ceramic/metal laminate, is investigated for its properties as a thermal shock resistant material. The deformations and fracture mechanisms were studied. It was shown that the lamination reduces the tensile stresses upon cooling, hence the damage in the ceramic layers, and that crack arrest mechanism due to crack blunting at the metallic interlayers was evidence. The residual strength was dramatically improved with compare to that of monolithic ceramics, and R-curve behavior was observed upon mechanical loading. The main feature of the laminate is the localization of the damage in several layers, and the ability to construct the system from different materials.
In a long term investigation, the ballistic failure mechanisms in alumina tiles subjected to impact of low caliber armor piercing rounds at 850 m/sec were analyzed. It was found that the major damage mechanisms in the tiles can be divided to two major categories: The quasi-static damage consists of radial cracks, cone crack and fragmentation of the cone, and
the dynamic damage, spall, resulted reflected stress waves from the surfaces and the edges of the tiles. The effect of confinement was studied using confinement frame, enables to generate large biaxial compressive deformation in the tile.
- D. Sherman and I. Be'ery, The Non-Linear Dynamic Rupture in Sapphire,Phys. Rev. Let.,80, 540-543, 1998. [PDF]
- D. Sherman, Impact Failure Mechanisms in Alumina Tiles on Finite Width Support and the Effect of Confinement, Int. J. Impact Eng., 24, 313-328, 2000. [PDF]
- H. Marom, D. Sherman, and Z. Rosenberg, Decay of Elastic Waves in Alumina,J. of Appl. Phys.,88, 5666-70, 2000. [PDF]
- D. Sherman and D. Schlumm, Analysis of Ceramic/Metal Laminate under Thermal Shock,J. Mat. Res.,16, 753-764, 2001. [PDF]
- H. Marom, D. Sherman, Z. Rosenberg, and N. Murray, On the Inelastic Shock Profile in Alumina,J. Appl. Phys.,92, 5886-91, 2002. [PDF]
- D. Shilo, D. Sherman, I. Be'ery, and E. Zolotoyabko, Large Local Deflections of a Dynamic Crack Front Induced by Intrinsic Dislocations in Brittle Single Crystals,Phys. Rev. Let.,89, 235504, 2002. [PDF]
- I. Be'ery, U. Lev, and D. Sherman, On the Lower Limiting Velocity of a Dynamic Crack in Brittle Solids,J. Appl. Phys.,93, 2429-2434, 2003. [PDF]
- D. Sherman and I. Be'ery, From Crack Deflection to Lattice Vibrations Macro to Atomistic Examination of Dynamic Cleavage Fracture,J. Mech. Phys. Solids,52, 1743-1761, 2004. [PDF]
- D. Sherman and I. Be'ery, Dislocations Deflects and Perturb Dynamically Propagating Cracks,Phys. Rev. Letters,93, 265501, 2004. [PDF]
- D. Sherman, Macroscopic and Microscopic Examination of the Relationship between Crack Velocity and Path and Rayleigh Surface Wave Speed in Single Crystal Silicon,J. Mech. Phys. Solids,53,2742-2757, 2005. [PDF]
- F. Atrash and D. Sherman, Analysis of the Residual Stresses, the Biaxial Modulus, and the Interfacial Fracture Energy of Low-K Dielectric thin films,J. Appl. Phys.,100, 103510, 2006. [PDF]
- D. Sherman, M. Markovitz, and O. Barkai, Dynamic instabilities in (111) Silicon. J. Mech. Phys. Solids, 56, 376-387, 2008. [PDF]
- J.R. Kermode, T. Albaret, D. Sherman, N. Bernstein, P. Gumbsch, M.C. Payne, G. Cs´anyi, and A. De Vita, Low Speed Fracture Instabilities in a Brittle Crystal,Nature,455, 1224-1227, 2008. [PDF]