Although bladed disks are nominally designed to be cyclically symmetric (tuned system). the vibration characteristics of all blades on a disk are slightly different due to the manufacturing tolerance. deviations in the material properties. and wear during operation. https://www.diegojavierfares.com/mega-offer-Classic-Premier-Navy-Drapery-Fabric-by-Premier-Prints-30-Yard-Bolt-super-offer/