title: A sparse digital signal model for ultrasonic nondestructive evaluation of layered materials.
abstract: Signal modeling has been proven to be an useful tool to characterize damaged materials under ultrasonic nondestructive evaluation (NDE). In this paper, we introduce a novel digital signal model for ultrasonic NDE of multilayered materials. This model borrows concepts from lattice filter theory, and bridges them to the physics involved in the wave-material interactions. In particular, the proposed theoretical framework shows that any multilayered material can be characterized by a transfer function with sparse coefficients. The filter coefficients are linked to the physical properties of the material and are analytically obtained from them, whereas a sparse distribution naturally arises and does not rely on heuristic approaches. The developed model is first validated with experimental measurements obtained from multilayered media consisting of homogeneous solids. Then, the sparse structure of the obtained digital filter is exploited through a model-based inverse problem for damage identification in a carbon fiber-reinforced polymer (CFRP) plate.
authors.affiliation: Dpt. of Structural Mechanics, University of Granada, Politécnico de Fuentenueva, 18071 Granada, Spain. Electronic address: nbochud@ugr.es.
authors.forename: N
authors.initials: N
authors.lastname: Bochud
authors.affiliation: Dpt. of Signal Theory, Networking and Communications, and CITIC, University of Granada, Campus de Fuentenueva, 18071 Granada, Spain. Electronic address: amgg@ugr.es.
authors.forename: A M
authors.initials: AM
authors.lastname: Gomez
authors.affiliation: Dpt. of Structural Mechanics, University of Granada, Politécnico de Fuentenueva, 18071 Granada, Spain. Electronic address: grus@ugr.es.
authors.forename: G
authors.initials: G
authors.lastname: Rus
authors.affiliation: Dpt. of Signal Theory, Networking and Communications, and CITIC, University of Granada, Campus de Fuentenueva, 18071 Granada, Spain. Electronic address: amp@ugr.es.
authors.forename: A M
authors.initials: AM
authors.lastname: Peinado
keywords: All-pole filter; Composites; Nondestructive evaluation; Signal modeling; Sparsity