DEFORMATION INDEX - CONCEPT FOR HYSTERETIC ENERGY-LOSS PROCESS

Historically, tan δ has been most frequently used as a relevant dynamic property of the material for hysteretic energy-loss processes. However, there is no fundamental reason why tan δ should be chosen, because the dynamic property that gives the best correlation depends on the type of deformation applied to the material. One convenient method to define the relevant dynamic viscoelastic property for the hysteretic energy-loss process is the concept of 'deformation index', which is discussed in this paper. The concept of deformation index can be effectively used to determine the relevant dynamic viscoelastic property which best correlates with the performance of the rubbery material. The concept also indicates the type of deformation that may govern a complex energy loss process, although, in this study, the underlying physical process was not experimentally identified.