In order to determine the effect that the presence of damage has on the dynamic characteristics of a vibrating structure, a beam element which has an L-section and contains a crack was developed. Stress intensity values were computed by modeling the crack as a set of four linear springs. Strain gage data taken from several specimens was also used to verify the stress distribution in the vicinity of the crack and hence the values of stress intensity used to compute the equivalent spring stiffness values. A model for a damaged beam element was then constructed by combining these spring stiffness values with the stiffness terms for an undamaged beam of similar cross section. The resulting element could then be used as a part of either finite element analysis or structural dynamic modification routines.
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