While toughening and damage might seem to be two contradictory concepts for the mechanics of crack growth, they are actually the same phenomena perceived from two different vantage points. Similarly, the concepts of extrinsic and intrinsic toughening, defined in terms of whether a toughening mechanism occurs behind or ahead of a crack, depend on the definition of a crack tip that, in the absenc...

http://dx.doi.org/10.1016/j.actamat.2015.07.022 1359-6454/ 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Department of Materials Science & Engineering, University of California, Berkeley, CA 94720, USA. E-mail address: [email protected] (R.O. Ritchie). 1 Intrinsic toughening mechanisms operate ahead of the crack tip to resistance to microst...

The effect of fiber orientation on the toughening of polymers by short glass fibers generally below their critical length was investigated using specimens with either well-aligned or randomly oriented fibers. The fibers were aligned by an electric field in a photopolymerizable monomer, which was polymerized while the field was still being applied. These materials were fractured with the aligned...

An appropriate conditioning noise exposure may reduce a subsequent noise-induced threshold shift. Although this "toughening" effect helps to protect the auditory system from a subsequent traumatic noise exposure, the mechanisms that regulate this protective process are not fully understood yet. Accordingly, the goal of the present study was to characterize physiological processes associated wit...

Mineralized tissues, such as bone and tooth dentin, serve as structural materials in the human body and, as such, have evolved to resist fracture. In assessing their quantitative fracture resistance or toughness, it is important to distinguish between intrinsic toughening mechanisms, which function ahead of the crack tip, such as plasticity in metals, and extrinsic mechanisms, which function pr...

Few studies have focused on a description of the fracture toughness properties of dentin in terms of resistance-curve (R-curve) behavior, i.e., fracture resistance increasing with crack extension, particularly in light of the relevant toughening mechanisms involved. Accordingly, in the present study, fracture mechanics based experiments were conducted on elephant dentin in order to determine su...

Analysis of the dynamic evolution of multilevel structure during martensitic transformations provides kinetics-based constitutive relations for transformation plasticity. Application in numerical modeling of ductile fracture by microvoid-softening-induced shear localization, in conjunction with metallographic study of crack-tip processes, identifies transformation toughening mechanisms operatin...

A study on the toughening of polyamide-6 (PA-6) with a new elastomeric modifier, brominated poly(isobutylene-co-p-methylstyrene) (BrXP-50), was conducted. Morphological analyses and mechanical tests were combined to evaluate the toughening mechanisms of modified PA-6 and the fracture mechanism of unmodified PA-6. We conclude that the fracture mechanism of unmodified PA-6 in the impact test is c...

It has been demonstrated that a Cs(2)O-stabilized leucite porcelain was susceptible to a stress-induced phase transformation, but toughening was not observed.1 It was hypothesized that if Cs(2)O-stabilized leucite core particles were added to a cesium-free matrix porcelain, selected or designed to enhance the toughening mechanism, toughening would occur. A commercial porcelain (VP) and a synthe...

in this paper, a systematic study on the effects of particle size and hybrid of two different size of silica nanoparticles on the toughening mechanisms of bisphenol-a epoxy was conducted. nanosilica particles with mean diameter of 17 nm and 65 nm were blended into epoxy system. probable synergy effects of these two nanoparticles on young’s modulus and yield strength have been investigated. resu...