The Elastic Wave Propagation in Rectangular Waveguide Structure: Determination of Dispersion Curves and Their Application in Nondestructive Techniques

Abstract

The use of mechanic waves for assessing structural integrity is a well-known non-destructive technique (NDT). The ultrasound applied in the guided wave in particular requires significant effort in order to understand the complexities of the propagation so as to develop new methods in damage detection, in this case, knowing the interaction between the wave propagation and the geometry of the waveguides is mandatory. In the present work, the wave propagation in rectangular steel rod is presented. In this study, the section dimensions were fixed as 5 × 15 [mm], a typical element of the flexible riser structural amour commonly used in the offshore oil industry. The studies here presented were restricted to [0, 100 KHz] frequencies. This frequency interval is in the range of commercial waveguide equipment commonly applied in ducts in NDT applications. The computation of the dispersion curves is performed by using three different methodologies: (i) analytical solutions, (ii) a method that combines analytical approaches with finite element methods (SAFE), and (iii) experimental method that extracted information from the rod using laser vibrometers and piezoelectric actuators. Finally, two applications based on the dispersion curves determined in the rectangular waveguide are presented to illustrate the possibilities of the curve dispersion knowledge related to the specific geometry in the development and application linked to NDT. The first application consists on showing the possibilities of the techniques that use a fiber grating Bragg cell (FGB) to measure the wave displacement and the second application involves the simulation of pre-fissured prismatic waveguide aimed at searching to induce three characteristic acoustic events. The model was built combining the finite element method and a version of the discrete element method.

Correlation of Vulnerability and Conservation Between Artistic Assets and Structural Elements: Campaign of Thermographic Surveys on the Frescoes of the Templar Church of San Bevignate

“…New technologies allow to conduct experimental investigations without harming the architectural quality of constructions, such innovations are exactly fitting with the disciplines inherent the heritage architectures [14,15]. Among the important factors influencing the seismic response of Heritage buildings, the masonry quality and the knowledge of its processes of stratification are certainly enclosed.…”

Feasibility of a Thermography Nondestructive Technique for Determining the Quality of Historical Frescoed Masonries: Applications on the Templar Church of San Bevignate

“…New technologies make it possible to intensify the experimental investigations without harming the architectural quality of buildings, such innovation is exactly fitting with the discipline inherent the heritage architectures [14][15][16][17]. Among the important factors influencing the seismic response of Heritage buildings, the masonry quality and the knowledge of its processes of transformation and stratification are certainly included.…”

Recording of Long Low-Amplitude Bulk Elastic Waves in Transparent Solid Waveguides by Digital and Classical Holography

“…Among these applications is the recording of elastic waves of different types in solids, in particular, shock and strain solitary waves (solitons) in solid waveguides. Linear elastic waves are widely used for the non-destructive analysis of internal structure and integrity of constructional elements [37]. Nonlinear elastic waves can be applied for the investigation of the nonlinearly elastic and viscoelastic properties of materials [38][39][40].…”