Measurement of stiffness coefficients of anisotropic materials from pointlike generation and detection of acoustic waves

Abstract

Threedimensional acoustic scattering of a sourcegenerated field from a cylindrical island

Tomographic Reconstruction of Elastic Constants in Composite Materials Using Numerical and Experimental Laser Ultrasonic Data

“…Each TOF measurement contributes in correcting many pixels lying on the path. It is quite different from the elastic constants determination from the phase or group velocities in the carefully chosen few directions along the desired symmetric or nonsymmetric directions in a homogeneous composite material [16][17][18][19][20][21][22][23][24]. In contrast, the tomography needs the scanning of the specimen from the possible views in order to reconstruct inhomogeneities and defects present in the specimen.…”

Acoustic waves generated by a line source in a viscoelastic anisotropic medium

“…The dependence with the frequency of the associated velocities provokes the smoothing of the wave forms, compared with those obtained in a purely elastic medium. 12,3 These blurred signals can be seen as consequences of chromatic aberrations subsequent to the distortion of the refraction curves with frequency.…”

“…[1][2][3] In this method, a laser beam is focused on a specimen in order to produce a line or pointlike acoustic source. At the high-power level, the laser operates in the ablation regime by vaporizing a small amount of surface material which, in turn, generates acoustic waves.…”

Measurement by Laser Generated Ultrasound of the Stiffness Tensor of an Anisotropic Material at Elevated Temperatures

“…This algorithm is consistent for the problem since owing to acoustic energy focusing, several velocities must be taken into account for one mode in a given direction [6]. Former approaches [9] have been developed for this identification problem for which such multiple contributions could not be introduced in the inversion algorithm.…”

“…A signal processing method has first been developed which has shown efficiency for measuring velocities of longitudinal and transverse mode generated through an elastic medium [6]. Owing to the viscosity of the matrix, the composite shows a viscoelastic behavior and waveforms are smoothed.…”