Fatigue measurements

The fatigue treatment signal is interrupted regularly for hysteresis measurements to monitor the development of the hysteresis shape, or at least the polarization values. These intermediate hysteresis measurements are performed after increasing time intervals, e.g. in such a 

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To investigate what factors might provide a mechanism to explain fatigue, measurements have been carried out on biopsy samples of muscle taken from volunteers performing live different fatiguing activities. 

Cyclic fatigue measurements require the specimen to be subjected to cyclic stress or strain of a higher amplitude than that employed for the simple dynamic test just described. The deformation must be of sufficient intensity to bring about specimen failure after a certain number of cycles, N. The value of stress leading to failure for a given N is typically 20% to 40% of the static tensile strength. 

Figure 3.17 Typical result of a fatigue measurement in combination with hysteresis measurements is usually depicted as the remanent polarization versus log cycles of the excitation signal.

Figure 19.2 Comparison of fatigue measurements at 300 kV/cm of a virgin (a) and a prefatigued (c) FECAP. The pre-fatigue procedure, performed at 150 kV/cm and 109 cycles (b), has suppressed P by a factor 10.

To find out possible reasons for the mechanical fatigue, measurements inside the pipe (noise) as well as in pipework and steel structure have verified the vibrations to be very low. Finally to avoid any risk of fatigue, grids supporting the candles have been installed. However, since the installation of this grid a tendency of bridging has been observed, which we did not experience earlier. 

Li, X. Bhushan, B. A review of nanoindentation continuous stiffness measurement technique and its applications. Mater. Charact. 2002, 48, 11-36. Li, X. Bhushan, B. Development of a nanoscale fatigue measurement technique and its application to ultrathin amorphous carbon coatings. Scripta Mater. 2002, 47, 473 79. 

Young s modulus was determined during the fatigue measurements. It was interesting that Young s modulus remained constant until failure, even for load amplitudes near the fracture strain (see Fig. 9). 

In the near future, industrial production problems will be studied, and a new characterization program will be prepared including some bending, creep, and fatigue measurements ... 

The presence of a chemically active environment may lead to a reduction in fatigue life for corrosion fatigue. Measures that may be taken to prevent this type of fatigue include the following ... 

The maximum test frequencies for cryogenic fatigue measurements can be much higher than at RT because of very low mechanical damping (tan Sm < 10 at 4.2 K) and absence of rate dependence below 1 kHz. The heat power generated per sample volume V can be estimated from the loss tangent. Young s modulus E iT), strain amplitude e, and test frequency/ ... 

Hun] Hardness, tensile and low cycle fatigue measurements Mechanical properties... 

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