Protein-based hydrogels usually do not exhibit high stretchability or toughness, significantly limiting the scope of their potential biomedical applications. Here we report the engineering of a chemically cross-linked, highly elastic and tough protein hydrogel using a mechanically extremely labile, de novo-designed protein that assumes the classical ferredoxin-like fold structure. Due to the lo...

Two experimental high strength steel weld metals were produced with 7 wt. % nickel and manganese at 2 or 0.5 wt. %. Neural network predictions that Mn reductions increase toughness were confirmed with impact energy increasing from 32 to 113 J at –40 °C. High resolution microstructural investigations showed that both weld metals contained mainly martensite at interdendritic regions and predomina...

this article aims to review various modes of fracture toughness of resin composites. also, this study intends to review the papers on the fracture mode, namely “fractography”, under scanning electron microscopy finding fracture initiation site, and the effect of filler content on the fracture toughness of resin composites. it will also review the effect of aging on the fracture toughness of res...

The authors conducted an investigation of mental toughness in a sample population of athletes who have achieved ultimate sporting success. Eight Olympic or world champions, 3 coaches, and 4 sport psychologists agreed to participate. Qualitative methods addressed 3 fundamental issues: the definition of mental toughness, the identification of its essential attributes, and the development of a fra...

High strength steels Q690+Q550 were welded using three different welding wires without preheating by gas shielded arc welding process. Microstructural characteristics of weld metals and nucleation mechanism of acicular ferrite were investigated by means of scanning electron microscope (SEM), energy dispersive spectrum (EDS) and transmission electron microscope (TEM). The straight Y-groove test ...

During crack growth of real materials, the total energy released can be partitioned into elastic and dissipative terms. By analyzing material models with mechanisms for dissipating energy and tracking all energy terms during crack growth, it is proposed that computer simulations of fracture can model crack growth by a total energy balance condition. One approach for developing fracture simulati...

We show that, if NP 6= ZPP, for any ε > 0, the toughness of a graph with n vertices is not approximable in polynomial time within a factor of 1 2 (n 2 ). We give a 4-approximation for graphs with toughness bounded by 1 3 and we show that this result cannot be generalized to graphs with a bounded toughness. More exactly we prove that there is no constant approximation for graphs with bounded tou...

Recently, a method for evaluating the fracture toughness of ceramics has been proposed by Fett based on the computed crack-opening displacements of cracks emanating from Vickers hardness indentations. To verify this method, experiments have been conducted to determine the toughness of a commercial silicon carbide ceramic, Hexoloy SA, by measuring the crack-opening profiles of such Vickers inden...

By partitioning the total stresses in a damaged composite into either mechanical and residual stresses or into initial and perturbation stresses, it was possible to derive two exact results for the energy release rate due to crack growth. These general results automatically include the effects of residual stresses, tractionloaded cracks, and imperfect interfaces. These effects are normally not ...

The toughness enhancement due to domain switching near a steadily growing crack in a ferroelastic material is analyzed. The constitutive response of the material is taken to be characteristic of a polycrystalline sample assembled from randomly oriented tetragonal single crystal grains. The constitutive law accounts for the strain saturation, asymmetry in tension versus compression, Bauschinger ...