Guided waves in plates with linear variation of thickness

Abstract

Guided waves represent promising non-destructive evaluation (NDE) techniques. Their advantage of long distance propagation is however hampered by complex wave scattering at each discontinuity along the investigated structure. These scattered waves can be used to locate and size possible defects. Theoretical investigation is a prerequisite step in the development of a NDE technique. Planar metallic structures with localized thickness variation imposed by design represent possible new industrial structures that could be tested using guided waves. The waves scattered at the region of variable thickness must be theoretically predicted and experimentally measured before any defect could be detected. Very few authors have investigated waveguides with continuous variation of thickness. Our previous numerical and experimental studies have proven the complexity of the scattering phenomenon in such cases. Among other remarks is the curved shape of the wave front. The present work investigates properties of the waves in the linear thickness variation region of the waveguide. A plain strain model is theoretically investigated and numerically tested using specialized finite elements based algorithms. Specific properties such as stress and displacements fields are determined by numerical simulation at several frequencies and slope angles.

Localization of defects in irregular waveguides by dispersion compensation and pulse compression

“…(1) is acceptable for the computation of its group delay. [11][12][13] Obviously, this requires that the GW considered in each segment for the computation of the group delay is generated by the incoming wave that has been considered in the previous segment of waveguide.…”

Study of the impact of truncations on wedge waves by using the laser ultrasound technique

“…HladkyHennion and co-workers [8,9] studied the propagation of acoustic waves in waveguides and in immersed waveguides by using the finite element method (FEM). Predoi et al [10] investigated the properties of the waves in the linear thickness variation region of waveguides. Further, the stress and displacements fields were determined by numerical simulation at several frequencies and slope angles.…”

Theoretical and experimental analysis of guided wave propagation in plate-like structures with sinusoidal thickness variations

“…In the literature the problem of wave propagation in structures with non-uniform geometry has been considered by many researchers ( [10][11][12][13][14][15][16][17][18]). The ultrasonic mode conversion phenomena under waveguide thickness variation employing the hybrid boundary element method was considered by Cho [10].…”

“…The ultrasonic mode conversion phenomena under waveguide thickness variation employing the hybrid boundary element method was considered by Cho [10]. The influence of the local thickness of the waveguide and the slope of the tapered plate on the modal conversion was investigated by Predoi et al [11]. The behavior of guided waves in specimens with Gaussian variation of their section, located between two areas of constant thickness was analyzed by Marical et al [12].…”