Quantitative nondestructive evaluation

Quantitative Nondestructive Evaluation (QNDE) provides techniques to assess deterioration of a material or a structure, and to detect and characterize discrete ¯aws. It plays, therefore, an important role in the prevention of failure. QNDE techniques are used in processing, manufacturing and for in-service inspection. QNDE is particularly important for the in-service inspection of high-cost and critical load-bearing structures whose failure could have tragic consequences. In this paper, we brie¯y review the most important techniques, and then we focus the discussion on quantitative ultrasonics, particularly for crack detection and for the determination of elastic constants. The important role of measurement models is emphasized. New techniques in quantitative ultrasonics are discussed, including laser-based ultrasonics and acoustic microscopy. The possible applications of neural networks are indicated. Attention is also devoted to the probability of detection concept and its relation to probabilistic fatigue methods and fatigue reliability