A missing cornerstone in the development of tough micro/nano fibre systems is an understanding of the fibre failure mechanisms, which stems from the limitation in observing the fracture of objects with dimensions one hundredth of the width of a hair strand. Tensile testing in the electron microscope is herein adopted to reveal the fracture behaviour of a novel type of toughened electrospun poly...

Plastic flow localization in porous elastic-viscoplastic solids is analyzed with an emphasis on the effects of material rate sensitivity and plastic potential surface curvature. The effect of rate sensitivity is included in a material model that accounts for a change of yield surface curvature in a rate-insensitive porous ductile solid. Shear band formation under plane strain and axisymmetric t...

We investigate the transient viscoelastic behavior of weakly strain-hardening fluids in filament stretching devices during uniaxial elongation and following the cessation of stretching. The numerical results are compared with experimental observations on a concentrated shear-thinning polystyrene solution which is well characterized by a multi-mode Giesekus model. The finite element computations...

For modern creep-resistant steels, ductility is primarily controlled by cavitation, since brittle rupture dominating during long-term service. In recent years, the present authors have formulated fundamental models for nucleation and growth of cavities that been verified to be able describe experiments austenitic stainless steels. These equations, together with dislocation creep, are used in th...

Notched metallic glasses (MGs) have received much attention recently due to their intriguing mechanical properties compared to their unnotched counterparts, but so far no fundamental understanding of the correlation between failure behavior and notch depth/sharpness exists. Using molecular dynamics simulations, we report necking and large notch strengthening in MGs with symmetric sharp-and-deep...

When a laminate of a thin metal film on a tough polymer substrate is stretched, the metal film may rupture at strains ranging from a few percent to a few tens of percent. This variation in the ductility of the metal film is modulated by the adhesion of the metal/polymer interface. To study this modulation, here we use the finite element method to simulate the co-evolution of two processes: debo...

forming limit diagram (fld) is an important diagram by which the formability of sheet metals is studied. strain rate is a very effective parameter influencing the fld which is, in turn, influenced by the forming velocity. in this work, forming limit diagram for st14 was investigated both experimentally and numerically. in addition, the effect of forming velocity was studied and the experiments ...

The dynamic necking instability of a rod of a non-linear viscoplastic material as formed in shaped charges is investigated. A two-dimensional linear Lagrangian perturbation method leads to a single fourth order partial differential equation with time-dependent coefficients. The growth of disturbancies depends of the interplay between the stabilizing inertial and viscous effects, and the destabi...

Galileo stereo images covering about 1500 km 2 of Uruk Sulcus on Ganymede have revealed two scales of ridges; (1) large-scale ridges and troughs spaced -6 km apart, corresponding to the "grooves" seen in Voyager images, and (2) small-scale ridges spaced hundreds of meters apart superimposed on the large-scale ridges. We interpret the small-scale ridges to be the result of tilt-block normal faul...