 Needleman's main research interests are in the computational modeling of deformation and fracture processes in structural materials, in particular metals.A general objective is to provide quantitative relations between the measurable (and hopefully controllable) features of the materials' micro-scale structure and its macroscopic mechanical behavior.Ongoing research projects involve studies of ductile fracture and ductile-brittle transitions; crack growth in heterogeneous microstructures with particular emphasis on the role of interfaces; nonlocal and discrete dislocation plasticity; fatigue crack growth; and fast fracture in brittle solids.