Cyclic frequency

The occurrence of thermal failures in a plastic depends not only on the cyclic frequency and applied stress level but also on the thermal and damping characteristics of the material. For example, polycarbonate has very little... 

The average reorientation frequency co can be defined as an average velocity with which a particle leaves a given potential well over two barriers with

rotational vibrations in the well defined by Eqs. (A2.2) and (A2.3) as a)q>=1[U"(Q)H]m, we arrive at ... 

Since the average reorientation frequency w is far less than the cyclic frequency of valence vibrations ah, expression (A2.8), with measured frequency values at close to coo, can approximately be rewritten as ... 

In (5.4.8) V is the direct voltage component, whereas A and u = 27r/ = (2n/T) are, respectively, the amplitude and the cyclic frequency of a harmonic modulation superimposed upon V, above some critical voltage VCT. 

The variation of sound velocity with cyclic frequency, to (= 2 a/), is given by... 

Fig. 7.1 Fatigue crack growth rate, da/dN, plotted as a function of stress intensity factor range, AK in AD 90 alumina in 1050°C air at cyclic frequencies of 0.13 Hz and 2 Hz at R = 0.15. After Ref. 34.

Figure 7.5 shows a comparison of the static and cyclic crack velocities for the alumina/SiC composite, similar to that illustrated in Fig. 7.2 for alumina. As seen for monolithic alumina, the ceramic composite undergoes slower rates of fracture when (1) fluctuations are introduced in the tensile loads and (2) the cyclic frequency is raised. The differences between static and cyclic crack growth rates are maximum at the lower Kmax levels. As in the case of unreinforced alumina, crack velocities estimated for cyclic loads on the basis of sustained load crack growth data (assuming identical failure mechanisms) are higher than those measured experimentally. 

Recent patents by Questair Industries claim to use ultrarapid PSA cycle times using adsorbent laminate modules. Cyclic frequency of 100 cycles per minute (-cycle time = 0.6 s) to possibly 600 cycles per minute (-cycle time = 0.1s) are claimed.46 47 The ultrarapid cycles can potentially increase the BSF further by two orders of magnitude and significantly decrease the adsorber size. It is not known to the authors whether these ultrarapid PSA units have been used for H2 purification applications. 

The single edge specimens were loaded under three-point bending at cyclic frequency of 10 Hz, stress ratio of 0.1. The FCGR tests were carried out in the laboratory air at the temperature of 20 °C and 700 °C. Several control tests of the composites were performed at the temperature of 800 °C. Optical and scanning electronic microscopy was used for analysis of microstructure and fracture micromechanisms of the materials. 

Vosikovsky, Fatigue-Crack Growth in an X-65 Linepipe Steel at Low Cyclic Frequencies in Aqueous Environments, Int. J. Mater. Technol. (Trans. ASME), Vol 97, 1975, p 298-304... 

To find the period of the oscillation T (i.e., the time elapsed between two successive peaks), use the well-known relationships co = 2nf and f = l/T where / = cyclical frequency. Thus... 

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