Relations between fracture toughness and microstructural details have been calculated for ductile materials based on a dilatational plasticity constitutive model that has recently been proposed. The model generalizes the Gurson model to account for both void growth and coalescence with explicit dependence on void shape and distribution effects. Based on a small scale yielding formulation of cra...

Low fracture toughness of ferroelectric ceramics calls for a reliability concern in the development of smart structures. For ferroelectrics under mechanical and electrical loadings, the intensified stress and electric fields in the vicinity of a crack-like flaw lead to domain reorientation. The switched domains induce incompatible strain near the flaw and consequently change the apparent fractu...

Systematic changes in composition were employed to increase the notch toughness of a variety of Fe-based Bulk Metallic Glasses (BMGs). The Fe50Mn10Mo14Cr4C16B6 BMG possessed very high hardness (e.g. 12GPa) but very low notch toughness (e.g. 5.7MPam) at room temperature, consistent with fracture surface observations of brittle features. Many of the other Fe-BMG variants, created to change the Po...

We consider toughness conditions that guarantee the existence of a hamiltonian cycle in ktrees, a subclass of the class of chordal graphs. By a result of Chen et al. 18-tough chordal graphs are hamiltonian, and by a result of Bauer et al. there exist nontraceable chordal graphs with toughness arbitrarily close to 4 . It is believed that the best possible value of the toughness guaranteeing hami...

Chen CC., K.M. Koh and Y.H. Peng, On the higher-order edge toughness of a graph, Discrete Mathematics 111 (1993) 113-123. For an integer c, 1 <c < 1 V(G) I1, we define the cth-order edye toughness of a graph G as The objective of this paper is to study this generalized concept of edge toughness. Besides giving the bounds and relationships of the cth-order edge toughness T,(G) of a graph G, we p...

In this letter we present the "Egg of Columbus" for making fibres with unprecedented toughness: a slider, in the simplest form just a knot, is introduced as frictional element to dissipate additional energy and thus demonstrating the existence of a previously "hidden" toughness. The proof of concept is experimentally realized making the world's toughest fibre, increasing the toughness modulus o...

Ultrahigh-resolution transmission electron microscopy and atomic-scale spectroscopy are used to investigate the origin of the toughness in rare-earth doped silicon carbide (RE-SiC) by examining the mechanistic nature of the intergranular cracking events which we find to occur precisely along the RE-decorated interface between the SiC grains and the nanoscale grain-boundary phase. We conclude th...

The purpose of this study was to compare the properties of 2 new dual-cure, bulk-fill restorative composite resins to those of a hybrid composite resin material. Depth of cure, fracture toughness, porosity, microleakage, and volumetric shrinkage properties were examined. With the exception of fracture toughness, significant differences were found among materials. Compared to the incrementally p...

The fracture toughness is a critical material property that determines engineering performance. However, as is well known for crystalline materials, if certain sample geometry and size requirements are not met, test results become sample-size dependent and difficult to compare between different studies. Here, the room-temperature fracture toughness of the Zr-based bulk metallic glass (BMG) Zr52...

Lightweight advanced high strength steels (AHSS) with aluminum contents between 4 and 12 weight percent have been the subject of intense interest in the last decade because of an excellent combination of high strain rate toughness coupled with up to a 17% reduction in density. Fully austenitic cast steels with a nominal composition of Fe-30%Mn-9%Al-0.9%C are almost 15% less dense than quenched ...