Research on working modal identification of electronic equipment by cross spectrum

Traditional technology of experimental modal analysis bases on the known input and output signals, and utilizes integrated information of both the excitation and responses to identify the modal parameter. In most of the actual conditions, only the response data is measurable while excitations are unknown. Thus modal parameter must be extracted only from responses. In allusion to this limitation, this paper puts forward to analyzing working mode of the electronic equipment by use of cross spectrum generated only by output responses. In order to get the response data, an integrated working modal test system has been built here. It is made up of available hardware and related software and is excited by the vibration table. This paper will use the test system and the cross-spectrum method to identify working modal parameters of a certain aviation equipment, which will then be applied to modify the finite element model (FEM). Results indicate that this test system is capable to acquire data in need, and that cross-spectrum method can identify parameters of the working mode, and also, the simulation results are in accordance with those from test. The whole system saves us much time and cost. It not only provides probability to simultaneously verify the working mode and vibration response, but also lays technical foundation for better appliance of the reliability simulation analysis method based on physics of failure (PoF) in practical projects.