We present a comprehensive computational analysis of the deformation of ultrafine crystalline pure Cu with nanoscale growth twins. This physically motivated model benefits from our experimental studies of the effects of the density of coherent nanotwins on the plastic deformation characteristics of Cu, and from post-deformation transmission electron microscopy investigations of dislocation stru...

In some circumstances, elastic-plastic deformation occurs in which both components of strain are finite. Such situations fall outside the scope of classical plasticity theory which assumes either infinitesimal strains or plastic-rigid theory for large strains. The present theory modifies the kinematics to include finite elastic and plastic strain components. For situations requiring this genera...

Al&act-This note examines two aspects of the theory which treats localization of deformation as a bifurcation from homogeneous deformation. The nsul~s arc obtained for solhis modelkd as ekstic-plastic and having smooth yield and plastic potential surfaces, but it is not required that inelastic strain increments be normal to the yield surface. Pint, it is demonstrated that discontinuous bifurcat...

An approach for modelling thermo-mechanical responses in a 3D arc welding process is developed using the Smoothed Particle Hydrodynamics (SPH) method. It is demonstrated for a simple arc welding configuration by using full three-dimensional elastoplastic analysis. The flow pattern of the filler material and the resulting plastic strain distribution are analysed. The effect of welding speed on t...

A detailed analysis is performed of the plastic deformation in a metal substrate fretted by a ̄atbottomed circular peg under steady normal load and cyclic tangential load. The substrate is coated with a thin layer of soft metal. Two limiting asymptotic problems are identi®ed which characterize small scale yielding behavior in the substrate in the vicinity of the corners of the peg. Deformation ...

The ability to map elastic or plastic strain on a microstructural level is critical to understanding and controlling deformation in structural alloys and ceramics. Electron back-scattered diffraction (EBSD) and related techniques, such as electron channeling patterns, have been used with some success to measure the plastic strain around cracks in Fe-3Si single crystals [1], Cu single crystals [...

At the microscopic level, plastic flow of a jammed, disordered material consists of a series of particle rearrangements that cannot be reversed by subsequent deformation. An infinitesimal deformation of the same material has no rearrangements. Yet between these limits, there may be a self-organized plastic regime with rearrangements, but with no net change upon reversing a deformation. We measu...

A combined scanning force and tunneling microscope is used to study the plastic deformation of a connective neck of nanometer dimensions formed by cohesive bonding between metal tip and substrate after contact. The applied force and conductance of the neck are measured simultaneously during the deformation process, which proceeds in alternating elastic and yielding stages. From these data the Y...

Fibronectin (FN) textiles are built as nanometer-thick fabrics. When uniaxially loaded, these fabrics exhibit a distinct threshold between elastic and plastic deformation with increasing stretch. Fabric mechanics are modeled using an eight-chain network and two-state model, revealing that elastic properties of FN depend on conformational extension of the protein and that plastic deformation dep...

The shape of metallic constrictions of nanoscopic dimensions ~necks! formed using a scanning tunneling microscope is shown to depend on the fabrication procedure. Submitting the neck to repeated plastic deformation cycles makes it possible to obtain long necks or nanowires. Point-contact spectroscopy results show that these long necks are quite crystalline, indicating that the repeated cycles o...