Quantitative assessment of the strength and toughness of bone has become an integral part of many biological and bioengineering studies on the structural properties of bone and their degradation due to aging, disease and therapeutic treatment. Whereas the biomechanical techniques for characterizing bone strength are well documented, few studies have focused on the theory, methodology, and vario...

Materials are often characterized in terms of their toughness, though more than one definition of toughness exists. Likely the most widely recognized means of defining material toughness, denoted here as τ, is by the area under the stress strain curve from a tensile test. Another important feature describing the nature of materials is that property known as brittleness, which has for a long tim...

The effects of temperature and loading rate on delamination growth were studied. The delamination fracture toughness of IM7/K3B was measured at 149°C, 177°C, and 204°C. At each temperature the tests were performed with a variety of loading rates so that the delamination initiated over the range of time from 0.5 sec to 24 hrs. The double cantilever beam (DCB) test was used to measure fracture to...

The notion of mimicking natural structures in the synthesis of new structural materials has generated enormous interest but has yielded few practical advances. Natural composites achieve strength and toughness through complex hierarchical designs that are extremely difficult to replicate synthetically. We emulate nature's toughening mechanisms by combining two ordinary compounds, aluminum oxide...

Pristine monocrystalline graphene is claimed to be the strongest material known with remarkable mechanical and electrical properties. However, graphene made with scalable fabrication techniques is polycrystalline and contains inherent nanoscale line and point defects--grain boundaries and grain-boundary triple junctions--that lead to significant statistical fluctuations in toughness and strengt...

We describe a non-destructive and inexpensive way of measuring the interface toughness between polymeric layers in microfabricated devices. A flat surface is bonded under pressure to a surface patterned with microscopic steps. When the pressure is removed, cracks develop at the interface as the material peels away from the steps. The toughness of the bond can be inferred from the crack lengths....

The indentation of a brittle film on a ductile substrate is analysed for obtaining the interface toughness. This measurement method of adhesion provides a simple technique for sampling a small area of the interface on practical geometries with common laboratory equipment. Mechanics solutions are presented to access the interface toughness, Fc, from measurements of the applied load, delamination...

The proportional relationships between the Charpy absorbed energy (CVN) and the KIC values have been established for a wide variety of steels. Several formulae have been proposed that predict KIC from CVN. The purpose of this study is to investigate, by means of compact testing fracture toughness specimens, the effective role of microstructure for estimation of the fractur...

Fracture toughness of re-entrant foam materials with a negative Poisson's ratio is explored experimentally as a function of permanent volumetric compression ratio, a processing variable. JIC values of toughness of negative Poisson's ratio open cell copper foams are enhanced by 80%, 130%, and 160% for permanent volumetric compression ratio values of 2.0, 2.5, and 3.0, respectively, compared to t...

The experimental evidence on the “endowment effect” (Kahneman et al. 1990) and the “self serving bias” in negotiations (Babcok and Loewenstein 1997) suggests that individuals enter a tough state of mind when they have to make a stand vis-avis somebody else. In this work we show how a toughness bias in bargaining may indeed be evolutionary viable. When the inherent toughness of the bargainer is ...