To closely analyze the dislocation structure evolution during nano-indentation, a multi-scale discrete dislocation plasticity code is modified to include nano-indentation loading. This code couples two length scales, discrete dislocation dynamics and continuum finite element analysis and has been successfully applied to analyze various problems in mechanics and materials science. Description of...

It is crucial to understand the creep behavior of Pb-free solder alloys in electronic packaging. Typical service environments are between 298 and 373K. The thermal mismatch induced stresses acting on solder joints result in extensive rate-dependent plastic deformation. The solder alloy is potentially the weakest component in the electronic package because normal operating temperatures are alrea...

Article history: Received: 31.01.2013. Received in revised form: 08.02.2013. Accepted: 08.02.2013. The indentation response of a closed-cell Al foam under the flat-end cylindrical indenter was experimentally investigated. The effects of indenter sizes, relative density of Al foam and boundary condition on the mechanical and energy absorption characteristics of indentation were also investigated...

Scleral indentation is widely used to examine the peripheral fundus, however it can increase the intraocular pressure (IOP) to high levels which can then affect retinal function. We evaluated the effects of scleral indentation on the macular function electrophysiologically. Intraoperative focal macular electroretinograms (iFMERGs) were recorded with and without controlling the IOP in 7 eyes. Wi...

The effect of indenting the skin at different rates on the perceived intensity of the stimulus was studied by indenting the skin of the fingertip with two triangular waveforms, given as a pair. The subjects were asked to judge which member of the pair was more intense. Perceived intensity was found to increase both with the depth and the speed of the indentation. In contrast, changes in the rat...

The analysis of indentation of rigid cylindrical wheels into frictional/cohesive soils is presented. Threeand two-dimensional numerical simulations were performed using the finite element code ABAQUS to assess the influence of soil strength parameters, dilatancy, and wheel geometry on the relationship between the indentation force and wheel sinkage. The effect of three-dimensionality in the ind...

Plastic heterogeneity in indentation is fundamental for understanding mechanics of hardness testing and impression-based deformation processing methods. The heterogeneous deformation underlying plane-strain indentation was investigated in plastic loading of copper by a flat punch. Deformation parameters were measured, in situ, by tracking the motion of asperities in high-speed optical imaging. ...

Time dependent plastic deformation in metals can occur at high temperatures. Typically the creep test is conducted to characterize the deformation features; however, the conventional uniaxial power-law creep test may be impractical for small scale materials. Accordingly, instrumented indentation techniques are frequently employed. This study concerns the employment of instrumented indentation t...

An experimental study on the indentation hardness of NiTi shape memory alloys (SMAs) by using a spherical indenter tip and a finite element investigation to understand the experimental results are presented in this paper. It is shown that the spherical indentation hardness of NiTi SMAs increases with the indentation depth. The finding is contrary to the recent study on the hardness of NiTi SMAs...

Dimensional analysis and the finite element method are applied in this paper to study spherical indentation of superelastic shape memory alloys. The scaling relationships derived from dimensional analysis bridge the indentation response and the mechanical properties of a superelastic shape memory alloy. Several key variables of a superelastic indentation curve are revealed and examined. We prov...