Metals fracture energy

A metal fracture characterized by considerable plastic deformation, the tearing of metal and an appreciable expenditure of energy, as occurs with repeated bending of a strip of metal. 

G. Elssner et al The influence of interface impurities on fracture energy of UHV diffusion bonded metal-ceramic bicrystals. Scripta Metall. Mater. 31, 1037-1042 (1994)... 

In principle, an equality between the thermodynamic work of adhesion of liquid-solid systems and the work needed to separate an interface might be expected for simple systems and this has been observed for failure of adhesive-polymer interfaces bonded by van der Waals forces, (Kinloch 1987). Similarly, empirical correlations of interfacial strengths and work of adhesion values of solidified interfaces have been reported for some nominally non-reactive pure metal/ceramic systems. However, mechanical separation of such interfaces is a complex process that usually involves plastic deformation of the lattices, and hence their works of fracture are often at least ten and sometimes one hundred times larger than the works of adhesion, (Howe 1993). Nevertheless, for non-reactive metal/ceramic couples, it is now widely recognised that the energy dissipated by plasticity (and as a result the fracture energy of the interface) scales with the thermodynamic work of adhesion (Reimanis et al. 1991, Howe 1993, Tomsiaet al. 1995). 

For metals and ionic solids, in which atoms interact only by omni-directional primary bonds, it is clear that S will be the fracture energy of sudi bonds normalised to unit area. For co-valently bonded solids, like diamond, the secondary bonding energies are negligible with respect to the primary bond strengths so that S will be given directly by the latter - again normalised to unit area. 

British thermal unit (Btu) A British thermal unit is the energy needed to raise the temperature of 1 lb of water ]°F (0.6°C) at sea level. As an example, one lb of solid waste usually contains 4,500 to 5,000 Btu. Plastic waste contains greater Btu than other materials of waste. See calorie energy consumption heat, brittle Easily broken, damaged, disrupted, cracked, snapped. See design-failure theory, Griffith metal fracture. 

The Charpy U-notch test refers to the ASTM E23 [12], Standard Test Methods for Notched Bar Impact Testing of Metallic Material. The test was used to determine fracture energy. A Tinius Olsen Change-O-Matic impact testing machine was used in this test. 

Fig.5. Measured fracture energy for thin metal films debonded from (un)treated polyimide...

Peel test Assuming the strain in the tab is negligible (e.g. if (1) the peel forces are very low or (2) a fabric- or plastic-backed rubbery adhesive or a relatively thick metallic substrate is the peeling member) and plastic bending of the tab does not occur, then adhesive fracture energy (critical strain energy release rate) is given by... 

In contrast to polyethylene and EVAs, Epoxide adhesives are thermosets and are much stiffer and less ductile. The adhesion fracture energy (Gc, see Fracture mechanics), between both unmodified and rubber-toughened epoxies (see Toughened adhesives) and several metals has generally been found to be much higher when microfibrous surfaces were involved (Table 2) ... 

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