Inspection of anisotropic composites using ultrasonic phased arrays

An approach, referred to as Velocity Variation Compensation (VVC), used to improve the inspection sensitivity of composites utilizing an ultrasonic phased array technique is described. This approach uses an ultrasonic immersion through-transmission technique to measure the velocity variation within an anisotropic composite material as the incident angle varies. Delay laws for phased array inspection were then modified using the measured velocity, and applied to a 5 MHz 32 elements phased array probe. Both methods were performed on the same sample, and the results showed that the detectability of defects was significantly increased.