Low-Cycle Fatigue Tests

In Fig. 7.15, an experimental investigation of damage and fracmre in fiber-reinforced ceramic composites (CMC) under low-cycle fatigue is shown. Several different composites are indicated, each reinforced with ceramic-grade Nicalon2 fibers, but with varying fiber architectures and matrix materials. 

Ce-TZP ceramics are characterized by relatively low critical stresses for the stress-induced t-m transformation (ffc,t fff)- Pronounced transformation plasticity is observed, due to which the Ce-TZP ceramics are relatively flaw-tolerant and their strength is not controlled by the initial flaw size, but rather by the critical transformation stress, the zone size and the strain-hardening effect. 

Materials Sintering parameters Average grain size (pm) Relative density (%TD) Young s modulus (GPa) Vickers hardness 

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Low cycle fatigue testing, 13 489, 491-493 Low density copolymer resins, for extrusion coating, 20 235t... 

Results of low-cycle fatigue tests of eye specimens of alloy T110 are adduced in Table 4. 

The character of fracture was identical at both levels of loading. The only difference was that at a higher load the fatigue cracks initiated from many centers. The results obtained were compared with data of low-cycle fatigue tests conducted earlier on similar eye specimens of alloy VT22 (Table 5). 

Permanent structural changes that occur in a material subjected to fluctuating stress and strain, which cause decay of mechanical properties. See S-N diagram. The ability of a material to plastically deform before fracturing in constant strain amplitude and low-cycle fatigue tests. See S-N diagram. ... 

American Society for Testing and Materials, "Standard Practice for Conducting Constant-Amplitude Low-Cycle Fatigue Testing," E606-80, 1969 Annuat Book of ASTM Standards. Vol. 03.01, pp. 601-613. 

Low-Cycle Fatigue Properties. Results of low-cycle fatigue experiments under strain control on as-worked W plate material at 815 °C are shown in Fig. 3.1-172. Low-cycle fatigue tests of pure W were performed in the temperature range between 1650 °C and 3300 C [1.184]. A relationship Afaiiure = exp(—aT) was found to be valid up to test temperatures of 2700 °C [1.185]. In all cases the failure mode was intercrystalline. Similar results were also obtained at a test temperature of 1232 °C [ 1.186]. The deformation behavior of Nb and Nb IZr under plastic-strain control at room temperature was investigated and cyclic stress-strain curves published [1.182]. 

Manual on Low-Cycle Fatigue Testing, ASTM STP 465, ASTM International, West Conshohocken, PA, 1969. 

ASTM E606— Recommended Practice for Constant Amplitude Low-Cycle Fatigue Testing... 

Fig. 1 4 Optical micrographs using (a) bright field and (b) polarized light, to document the grain structure of 95.5Sn-3.9Ag-0.6Cu solder joints between Cu subjected to low-cycle fatigue testing...

R. Sandstrom, J.O. Osterberg, and M. Ny-len. Deformation Behavior During Low Cycle Fatigue Testing of 60Sn-40Pb Solder, Mater Sci Technol. Vol 9,1993, p 811-819... 

Mechanical low-cycle fatigue tests were performed (Ref 27) on several ICA joints and measured the resistance changes with high-sensitive micro-ohm technique. The resistance was observed to increase apparently at the initial stage of the tests, while the force required for the same deformation amplitudes decreased gradually. The authors attributed this phenomenon to the formation of wear tracks from filler frictions. However, they insisted that the influence of filler motion is limited and the dominant failure mechanism is interfacial fracture of the joint. 

Feltner, C.E., Mitchell, M.R. 2BASIC Research on the cyclic deformation and fracture behaviour of materials. Manual Low-Cycle Fatigue Test. Am. Soc. Test. Mater. STP 465, 27-66 (1969)... 

Yokobori, T., Kawasaki, T., Nakanishi, S., Kawaghishi, M. Some experiments on heavy section specimen under low-cycle fatigue testing. Met. Sci. J. 5(1), 25-33 (1969)... 

Low-cycle fatigue tests were carried out under strain control conditions at a frequency of 0.8 Hz and an i -ratio of 0.8. A characteristic response similar to the effect of lead concentration on plasticity described in the previous section was also observed in the case of low-cycle fatigue. That is, an abrupt reduction in fatigue life was observed with just a 0.1% Pb addition, but then the fatigue life progressively improved with increased Pb additions up to the maximum level tested (0.5% Pb). The fatigue life of the 0.5% Pb alloy was found to be nearly equivalent to the unleaded benchmark alloy [74]. 

After Wild [93]. Low-cycle fatigue tested at 1/15 CPM, 25°C fatigue point established by the resistance increase of 0.03 mfl [93]. 

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