Open Access Open Access  Restricted Access Subscription Access

Understanding the Effects of a Breathing Crack on the Dynamic Response of Cantilever-Type Structures for Damage Detection

A. U. REHMAN, K. WORDEN, J. A. RONGONG

Abstract


The presence of a crack causes local variations in the stiffness of a system and thus affects its mechanical behaviour. Considering a turbomachinery blisk as a cantilevertype structure, an investigation into the effect of the presence of a breathing crack of varying depth is carried out in this paper. This investigation provides the preliminary basis for damage detection in turbomachinery blades. A dog-bone type specimen is selected for this study. An impulsive excitation technique is used to excite the specimen model and the response is obtained at different locations. Relationships between the impulse response and crack depth/coefficient of friction are obtained. In addition, crack-face tracking is also accomplished for different modes of vibrations. The effect of crack depth and coefficient of friction on friction stresses, crack-face pressures and damping levels is investigated. The obtained results are then correlated to damage detection techniques in cantilever type structures.

Full Text:

PDF