Combined integral and FE analysis of broad-band random vibration in structural members

The paper addresses a new approach for the description of broad-band random vibrations of components in complex structures. Random vibrations at low frequencies are determined by methods of computational structural dynamics. Vibrations at high frequencies are described in an integral form, i.e. by means of combination of the Bolotin method of integral estimates and the methods of high-frequency dynamics. The fuzzy intermediate range between the upper frequency bound of efficient numerical computations and the lower bound of the high frequency approach is examined by means of an example. The methodology essentially reduces the computing costs without noticeable loss of information in the high frequency domain. Further, the approach enables one to indicate a frequency domain wherein the vibration localisation within structural members occurs. The applicability of the concept is demonstrated by computing the broad band random vibrations of a thin-walled cover of an engine head.