Seismic evaluations of many existing deck-truss bridges have revealed the vulnerability of their substructure and members of their superstructure. An innovative retrofit strategy developed by the authors includes replacement of the existing non-ductile end and lower-end bracing with ductile panels by incorporating energy dissipating devices to act as fuses, which can yield and dissipate energy ...

High-velocity (-•2 to -•5 km/sec) impacts into octahedrite iron meteorites (Gibeon, El Sampal, and Arispe), steel, and iron targets were made at the NASA-Ames Vertical Gun Facility. The experiments clearly revealed the brittle behavior of meteorites at very low temperatures (<200 ø K) as indicated by spallation of the crater rim and the development of deeply penetrating fractures in the meteori...

Fatigue is the primary cause of failure of crankshafts in internal combustion engines. The cyclic loading conditions and the stress concentrations in the crank pin fillets are unavoidable, and can result in fatigue failure. The objectives of this study were to compare the fatigue behavior of forged steel and ductile iron crankshafts from a one-cylinder engine as well as to determine if the fati...

A molecular-dynamics study of ductile and brittle fracture in model noncrystalline solids Abstract Molecular-dynamics simulations of fracture in model amorphous solids are shown to exhibit brittle or ductile behavior depending on small changes in interatomic potential. Yet, simulations of these two model solids under pure shear reveal no significant difference in their ultimate yield stress. To...

Kevlar is a type of aramid fibers which is characterized by high strength to low weight ratio. This material is widely used in bulletproof vests and helmets, in which it creates a barrier to projectiles to protect specific objectives, laminated tubes and pressure vessels, etc. In this study the ballistic behavior of Kevlar /epoxy composite and Kevlar fabric is investigated. The results showed t...

We report a close correlation between the dynamic behavior of serrated flow and the plasticity in metallic glasses (MGs) and show that the plastic deformation of ductile MGs can evolve into a self-organized critical state characterized by the power-law distribution of shear avalanches. A stick-slip model considering the interaction of multiple shear bands is presented to reveal complex scale-fr...

At low temperatures silicon is a brittle material that shatters catastrophically, whereas at elevated temperatures, the behavior of silicon changes drastically over a narrow temperature range and suddenly becomes ductile. This brittle-to-ductile transition has been observed in experimental studies, yet its fundamental mechanisms remain unknown. Here we report an atomistic-level study of a funda...