Damage location indicators from substructure mode shapes

When damage occurs in a substructure its modes of vibration will be changed but the modes of other substructures will be unaffected. Also the higher m odes will not participate in the deflections of undamaged substructures. Th ese observations are used to establish the necessary and sufficient conditi ons that identify an undamaged substructure. Two damage location indicators are then formulated and applied to a numerical example. Both indicators ar e successful in locating the damage.