 This phenomenon is studied in relation to turbine disks, for example; it can cause an increase of the forced response that can bring about unexpected failures due to fatigue.Mistuning is caused by manufacturer tolerances, non-homogeneity of the material, the usage, etc., and so it is unavoidable.It has been observed that the amount of increase in the forced response of mistuned turbine disks strongly depends on the physical characteristics of the disk itself