Mechanical Engineering Seminar by Dr. Ankit Srivastava
When: Wednesday,
January 14, 2015
1:15 PM
-
2:30 PM
Where: Textiles Building 101E
Description: The Mechanical Engineering Department is pleased to announce the following SEMINAR on Wednesday, 1/14/15 from 1:15 p.m. to 2:30 p.m. in the Textile Building, Room 101E.
SPEAKER is Dr. Ankit Srivastava of Brown University.
TOPIC is Correlating Ductile Fracture Surface Roughness and Fracture Toughness.
ABSTRACT is:
Two fundamental questions in the mechanics and physics of fracture are:
(i) What is the relation between observable features of a material's microstructure and its resistance to crack growth?
(ii) What is the relation between observable features of a material's microstructure and the roughness of the fracture surface?
An obvious corollary question is: What is the relation, if any, between a material's crack growth resistance and the roughness of the corresponding fracture surface? My presentation will be focused on the results of finite element calculations of mode-I ductile crack growth aimed at addressing these questions. At room temperature, ductile fracture of structural metals generally occurs by the nucleation, growth and coalescence of micron scale voids. In the calculations, an elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. In a variety of structural alloys, the distribution of void nucleating particles can be idealized as involving two size scales; larger inclusions that nucleate voids at relatively small strains and smaller particles that nucleate voids at much larger strains. In the calculations the larger inclusions (e. g. MnS inclusions in steels) are discretely modeled to introduce a length scale, while the smaller particles (e.g. carbides in steels) are taken to be homogeneously distributed. The crack growth resistance is quantified in terms of JIC and the tearing modulus, TR. The Hurst exponent of the correlation function of the fracture surface height distribution, a quantity typically used to characterize the fracture surface roughness, is also calculated. In addition, the fracture surface roughness is investigate using the full statistics of the fracture surface height distribution. Possible connections between quantitative measures of crack growth resistance and quantitative measures of fracture surface roughness are explored and related to the nature of the ductile crack growth process.
ABOUT THE SPEAKER:
Ankit Srivastava is currently working as Postdoctoral Fellow at Brown University He is currently working on Micromechanics of plastic deformation and phase transformation in multiphase steel. He received his doctoral degree in Materials Science and Engineering from University of North Texas. His doctoral research addressed on Mechanics and Mechanisms of Creep and Ductile Fracture. His research interests are focused on micromechanical modeling of deformation and fracture of materials with spatial and temporal heterogeneities using tools of solid mechanics.
For more information please contact Dr. Vijay Chalivendra (vchalivendra@umassd.edu, 508-910-6572).
All are welcome. Mechanical Engineering students are encouraged to attend.
Light refreshments will be served.
SPEAKER is Dr. Ankit Srivastava of Brown University.
TOPIC is Correlating Ductile Fracture Surface Roughness and Fracture Toughness.
ABSTRACT is:
Two fundamental questions in the mechanics and physics of fracture are:
(i) What is the relation between observable features of a material's microstructure and its resistance to crack growth?
(ii) What is the relation between observable features of a material's microstructure and the roughness of the fracture surface?
An obvious corollary question is: What is the relation, if any, between a material's crack growth resistance and the roughness of the corresponding fracture surface? My presentation will be focused on the results of finite element calculations of mode-I ductile crack growth aimed at addressing these questions. At room temperature, ductile fracture of structural metals generally occurs by the nucleation, growth and coalescence of micron scale voids. In the calculations, an elastic-viscoplastic constitutive relation for a progressively cavitating plastic solid is used to model the material. In a variety of structural alloys, the distribution of void nucleating particles can be idealized as involving two size scales; larger inclusions that nucleate voids at relatively small strains and smaller particles that nucleate voids at much larger strains. In the calculations the larger inclusions (e. g. MnS inclusions in steels) are discretely modeled to introduce a length scale, while the smaller particles (e.g. carbides in steels) are taken to be homogeneously distributed. The crack growth resistance is quantified in terms of JIC and the tearing modulus, TR. The Hurst exponent of the correlation function of the fracture surface height distribution, a quantity typically used to characterize the fracture surface roughness, is also calculated. In addition, the fracture surface roughness is investigate using the full statistics of the fracture surface height distribution. Possible connections between quantitative measures of crack growth resistance and quantitative measures of fracture surface roughness are explored and related to the nature of the ductile crack growth process.
ABOUT THE SPEAKER:
Ankit Srivastava is currently working as Postdoctoral Fellow at Brown University He is currently working on Micromechanics of plastic deformation and phase transformation in multiphase steel. He received his doctoral degree in Materials Science and Engineering from University of North Texas. His doctoral research addressed on Mechanics and Mechanisms of Creep and Ductile Fracture. His research interests are focused on micromechanical modeling of deformation and fracture of materials with spatial and temporal heterogeneities using tools of solid mechanics.
For more information please contact Dr. Vijay Chalivendra (vchalivendra@umassd.edu, 508-910-6572).
All are welcome. Mechanical Engineering students are encouraged to attend.
Light refreshments will be served.
Topical Areas: University Community, College of Engineering, Mechanical Engineering