Tensile fatigue test

It is noted, however, that both of the above CaF2 and Ti02 nanoceramics had some amount of porosity. This may account for an apparent soft behavior related to the superplastic deformation at low temperature, which does not yet reveal the plastic deformation characteristics in nanoceramics. Localized superplastic deformation under cyclic tensile fatigue tests was observed by Yan et al. on 3Y-TZP nanoceramics at room temperature [25], The micromechanism behind this phenomenon is argued to be essentially governed by grain-boundary diffusion. The contribution of dislocation slip might be in operation as a parallel mechanism to develop slip band-like microfeatures. 

Battelle Memorial Institute [ ], Kaiser Aluminum and Chemical Corporation [-], Aluminum Company of America [ ], and Martin-Denver [ ] have all contributed to the slowly increasing amount of low-temperature fatigue testing information. The only true tensile fatigue testing at 20°K among these is being done by Martin and, to date, has been applied to metals only. 

Table I. Tensile Fatigue Tests on Epon 828/181 Glass Laminate...

The complex of equipment developed for tensile fatigue tests consists of four basic items. The first is the closed-loop liquid-hydrogen testing system of which, the cryostat, the second item, becomes an integral part. The modified fatigue machine and the instrumentation system form the third and fourth items. 

A tensile fatigue test is carried out on a polyethylene, with the strain varying from 0 to 1% at 300 Hz. Calculate the rate of energy dissipation per unit volume if E = 1.0 GPa, E" — 20 MPa, and hence the initial heating rate, if the product of density and specific heat is 1.2x 10 Jm- K- ... 

The isothermal tensile fatigue tests were performed at 566°C (1050°F) in air. The specimen geometry was the same edge loaded tensile geometry used in the creep tests. The test cycle involved linearly increasing the tensile stress from the minimum value (14 MPa) to the maximum value over a one second period. The sample was held at the maximum stress for one second and then the stress was linearly reduced to the minimum value over an additional one second period. 

Figure 2-59. Tensile fatigue testing machine. (Courtesy of Fatigue Dynamics, Inc.)...

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