Alternating stress

Corrosion Fatigue failure by cracking caused by reversing alternating stress in the presence of a corrosive environment. 

Fatigue failure of metal under conditions of repeated alternating stress. 

Stresses from varying winds are general alternating stress loads and occur over wide areas of the structure. When the wind changes direction, the stress frequently changes... 

In the 1950 s an investigation into the effect of ultrasonic vibrations on the mechanical properties of metals showed that superimposing an alternating stress on a workpiece greatly affected the process rate and considerably reduced the force necessary for work-piece deformation [20]. 

Eqs. (4.140) and (4.150)-(4.152) are used to evaluate the response of the model composites in cyclic loading and the displacements 6 and 8, can be expressed as a function of the alternating stress, Aff, and the number of cycles, N. In experiments, degradation of the interface properties, e.g., the coefficient of friction, p or A(= 2pjfc/a), can also be expressed in terms of the cyclic loading parameters, Aoptical methods (with a microscope) or by means of more complicated instruments (see for example Naaman et al. (1992)) in fiber pull-out. Alternatively, they can be directly determined from the load and load-point displacement records in the case of fiber push-out. 

Impeller Problems The high-speed rotation of the impeller of a centrifngal compressor imparts the vital aerodynamic velocity to the flow within the gas path. The buffeting effects of the gas flow can canse fatigue failures in the conventional fabricated shrouded impeller due to vibration-induced alternating stresses. These may be of the following types ... 

The energy which is lost in each cycle when an alternating stress is applied to a viscoelastic material may be expressed as follows ... 

Piezoelectric measurements in bulk samples can also be made by applying an alternating stress and measuring the charge developed. Recent work in this area has been reported by Damjanovic and co-workers using a dynamic press apparatus [17]. In that work, the importance of measurement frequency and stress amplitude was also clearly pointed out. 

Fig. 2.2 Vector representation of an alternating stress leading and alternating strain by phase angle S. (From ref. [1])...

Corrosion fatigue 1900 Alternating stresses and chemical environment together cause corrosion fatigue... 

Malagoli, D, Gobba, E, and Ottaviani, E. 2003. Effects of 50-Hz magnetic fields on the signalling pathways of fMLP-induced shape changes in invertebrate immunocytes the activation of an alternative stress pathway. Biochim Biophys Acta 1620, 185-190. 

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