Patent ID: 8831895

Claim:
A method for detecting and evaluating structural defects, comprising the steps of: storing baseline data associated with a structure, the baseline data representative of sensed ultrasonic waves that were transmitting into the structure with no defects; transmitting ultrasonic waves into the structure from a plurality of actuators that are coupled to the structure; sensing, with a plurality of sensors that are coupled to the structure and spaced apart from the actuators, the ultrasonic waves transmitted into the structure from the plurality of actuators, to thereby generate and supply sensor data; calculating signal difference coefficients from the baseline data and the sensor data; and spatially mapping the calculated signal difference coefficients to detect one or more structural defects in the structure, wherein the signal difference coefficients (SDCs) are calculated using the following equation: SDC ij = ∑ k = 1 K ⁢ ( X e ⁢ ⁢ 0 ⁢ ⁢ k - μ x e ⁢ ⁢ 0 ) ⁢ ( X ek - μ x e ) ∑ k = 1 K ⁢ ( X e ⁢ ⁢ 0 ⁢ ⁢ k - μ x e ⁢ ⁢ 0 ) 2 ⁢ ∑ k = 1 K ⁢ ( X ek - μ x e ) 2 , wherein: X e0k , X ek are envelopes associated with the baseline data and sensor data, respectively, μ xe0 , μ xe are mean values of the baseline data and sensor data, respectively, and i and j are indices associated with a particular actuator and sensor, respectively.