The indentation slope curve from a spherical indentation on elastic-plastic materials is examined. By comparing it with that of an linear elastic material of the same elastic properties, we found that the start point of plastic yielding for an elastic-plastic material can be easily located from the indentation slope curve. Based on this analysis, a simple but effective method is proposed tomeas...

Indentation methods are finding increasing use in the study of mechanical properties of bulk and thin-film materials over a wide range of size scales (e.g., [1,2]). With the increasing sophistication of instrumented, depth-sensing indentation equipment and of computational methods to model the deformation of materials subjected to indentation, there is growing interest in studying the elastopla...

We find power-law behaviors of grain velocity in both propagation and backscattering in a gravitationally compacted granular chain with nonlinear contact force. We focus on the leading peak of the velocity signal which decreases in a power-law d−α, where d is the location of the peak, as the signal goes down. The ratio of backscattered to incident leading velocity also follows a power-law d −β ...

The force-depth behavior of indentation into fibrillar-structured surfaces such as those consisting of forests of microor nanoscale tubes or rods is a depth-dependent behavior governed by compression, bending, and buckling of the nanotubes. Using a micromechanical model of the indentation process, the effective elastic properties of the constituent tubes or rods as well as the effective propert...

Bone fragility is a concern for aged and diseased bone. Measuring bone toughness and understanding fracture properties of the bone are critical for predicting fracture risk associated with age and disease and for preclinical testing of therapies. A reference point indentation technique (BioDent) has recently been developed to determine bone's resistance to fracture in a minimally invasive way b...

It has been argued previously [1-3] that a first-order invariant covering theory of Maxwell’s electromagnetism (EM) originally proposed by Hertz [4] provides not only a formally more comprehensive approach to EM description but one that is more competent to describe the weak-field (single photon) limit. This claim depends on a specific physical interpretation of the Galilean invariant formalism...

Psychophysical tests on human subjects showed that judgments of skin indentation depth made when the fingertip was indented at rates from 0.2 to 16 mm/sec were quite insensitive to changes in indentation velocity. Similar results were obtained on the forearm at indentation velocities of 0.4 to 16 mm/sec. Recordings were made from mechanoreceptors in the monkey's hand that were able to respond o...

introduction: nano-indentation has recently been employed as a powerful tool for determining the mechanical properties of biological tissues on nano and micro scales. a majority of soft biological tissues such as ligaments and tendons exhibit viscoelastic or time-dependent behaviors. the constitutive characterization of soft tissues is among very important subjects in clinical medicine and espe...

thermoplastic honeycombs based on polypropylene are one of the latest types of cores used in sandwich structures. up to now there have been few experimental and modelling studies on the mechanical behaviour of sandwich structures with thermoplastic cores. in this paper, by considering the similar properties of foams and thermoplastic honeycombs, attempts are made to model the static indentation...