Modal power flow analysis of a damaged plate

Variation of the modal reactive power distribution of a damaged plate is analyzed. Large variation of local reactive power flow in or around the damage region of a plate under resonant vibration is related to the change of strain and kinetic energies in the damage region. Feasibility of damage identification based on the detection of this local variation of modal reactive power flow in a structure is studied. Compared with the damage identification techniques based on the determination of the active power flow in a damaged plate, the proposed method only requires data of a vibration mode shape of the structure and it is easier to apply in practice. Two common types of damage have been tested for identification, the first with a region of reduced stiffness in the plate while the second with a small hole in the plate. Numerical tests show that the proposed method is effective for both types of damage and the modal power flow is more sensitive to the change of plate stiffness than the strain mode shape in the test case.