Transverse vibrations, structural-dynamical

Conventional infrared spectra of powdery materials are very often used for studying solid hydrates in terms of sample characterization (fingerprints), phase transitions, and both structural and bonding features. For the latter objects mostly deuteration experiments are included. However, it must be born in mind that the band frequencies observed (except those of isotopically dilute samples (see Sect. 2.6)) are those of surface modes rather than due to bulk vibrations, i.e., the transverse optical phonon modes, and, hence, not favorably appropriate for molecular and lattice dynamic calculations. 

In spite of these ongoing developments, today almost all riser design analyses are performed by empirical methods. Static analysis is generally based on steady current loads (uniform or shear) and provides the riser deflected shape, stresses at various points on the riser, top and bottom angles, and its structural mode shape under load. Dynamic analysis considers both the inline and transverse unsteady loads. In addition to the riser shapes and stresses, it provides the vortex induced vibration, and fatigue life of the riser. 

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