Discrete Dislocation Modeling of Plastic Flow Processes

SEMINARIOS INTERUNIVERSITARIOS MECÁNICA Y MATERIALES
Speaker: Professor Alan Needleman
Department of Materials Science & Engineering at the University of North Texas, Denton, Texas, USA
Fecha y hora: 29 de octubre de 2009 a las 13:00 h. (café desde 12:30).
Lugar: Sala Verde, 1ª Planta, E.T.S.I. Caminos, Canales y Puertos, C/Profesor
Aranguren, Univ. Politécnica Madrid, Ciudad Universitaria.
Discrete Dislocation Modeling of Plastic Flow Processes
An overview will be given of some discrete dislocation analyses of plastic flow in ductile crystals. In
discrete dislocation plasticity, conventional initial/boundary value problems are solved but instead of
a phenomenological plastic constitutive relation plastic flow arises from the collective motion of
discrete dislocations which are modeled as line singularities in an elastic medium. The long range
interactions between dislocations are accounted for by elasticity but the short range interactions are
included via constitutive rules. The focus will be on phenomena that are not well-modeled by
conventional phenomenological theories of plasticity. Predictions for a variety of phenomena will be
discussed including: (i) the size dependence of micron-scale single crystal pillars in contrast to the
size independence for polycrystalline pillars; (ii) the scaling with material properties in fatigue; (iii)
stress evolution in thin films; and (iv) the development of surface roughness during indentation and
sliding.
Breve CV de Alan Needleman
Alan Needleman is highly recognized for his theoretical contributions in both mechanics and
materials science. He completed his Ph.D. in Engineering at Harvard University in 1970. He then
spent five years in Applied Mathematics at MIT before moving to Brown University where he was
Florence Pirce Grant University Professor and Professor of Engineering until June 2009. He is now
Professor of Materials Science & Engineering at the University of North Texas. His contributions
include the development of a ductile fracture computational methodology, the development of
cohesive surface methods for fracture analysis and creation of a framework that enables using
discrete dislocation plasticity to solve general boundary value problems. He was awarded a
Guggenheim Fellowship in 1977, is a member of the National Academy of Engineering and of the
American Academy of Arts and Sciences. He has been awarded the Prager Medal by the Society of
Engineering Science, the Drucker Medal by the American Society of Mechanical Engineers and has
been recognized by ISI as a Highly Cited Author in both the fields of Engineering and Materials
Science. Alan Needleman also holds honorary doctorates from The Technical University of
Denmark and Ecole Normale Superior de Cachan (France).
Contacto: Coordinador Científico: Dr. José Merodio (jose.merodio@upm.es). Asistencia libre.
adicional: yolanda@mecanica.upm.es 91-3366760.
Información
Con la colaboración de: Dpto. Mecánica de los Medios Continuos y T. Estructuras (UPM), Dpto.
Ciencia de los Materiales (UPM), Dpto. Mecánica Estructural y Construcciones Industriales (UPM),
IMDEA-Materiales, Dpto. Matemáticas (IMAFF, CSIC).