Optimal nondestructive test design for maximum sensitivity and minimal redundancy for applications in material characterization

An approach to nondestructive test (NDT) design for material characterization and damage identification in structural components, and more generally in solid continua, is presented and numerically tested. The proposed NDT design approach is based on maximizing a measure of the sensitivity of the test responses to changes in the material properties of the structure while also maximizing a measure of the difference in the response components. As such, the optimally designed NDT provides significant improvement in the ability to solve subsequent inverse characterization problems by extracting the maximum amount of non-redundant information from the system to increase the inverse solution observability. The NDT design approach is theoretically able to include any and all possible design aspects, such as the placement of sensors and actuators and determination of actuation frequency, among others. Through simulated test problems based on the characterization of damage in aluminum structural components utilizing steady-state dynamic surface excitation and localized measurements of displacement, the proposed NDT design approach is shown to provide NDT designs with significantly higher measurement sensitivity as well as lower information redundancy when compared to alternate test approaches. More importantly, the optimized NDT methods are shown to provide consistent and significant improvement in the ability to accurately inversely characterize variations in the Young's modulus distributions for the simulated test cases considered. (paper)