Guided wave dispersion is commonly assessed by Fourier analysis of the field along a line, resulting in frequency-wave-number curves. In anisotropic plates, point source can generate multiple branches pertaining to same modal surface, which arise due angle between power flux and vector. We show that this phenomenon very particular near zero-group-velocity points occurs all directions independent degree anisotropy. Stationary phase accurately describe measurements on monocrystalline silicon...

Dispersion curves of elastic waveguides exhibit points where the group velocity vanishes while wavenumber remains finite. These are so-called zero-group-velocity (ZGV) points. As elastodynamic energy at these confined close to source, they practical interest for nondestructive testing and quantitative characterization structures. applications rely on correct prediction ZGV In this contribution, we first model resonances in anisotropic plates based appearance an additional modal solution. The...

Lamb waves are elastodynamic guided in plates and used for non-destructive evaluation, sensors, material characterization. These applications rely on the knowledge of dispersion characteristics, i.e., frequency-dependent wavenumbers. The interaction a plate with an adjacent fluid leads to nonlinear differential eigenvalue problem square root term describing exchange energy surrounding medium, e.g., via acoustic radiation. In this contribution, spectral collocation scheme is applied...

To produce sounds, we adjust the tension of our vocal folds to shape their properties and control pitch. This efficient mechanism offers inspiration for designing reconfigurable materials adaptable soft robots. However, understanding how flexible structures respond a significant static strain is not straightforward. complexity also limits precision medical imaging when applied tensioned organs like muscles, tendons, ligaments blood vessels among others. In this article, experimentally...

Electroelastic waves in piezoelectric media are widely used sensing and filtering applications. Despite extensive research, computing the guided wave dispersion remains challenging. This paper presents semi-analytical approaches based on spectral methods to efficiently reliably compute curves. We systematically assess impact of electrical boundary conditions a 128° Y-cut LiNbO3 wafer, examining open–open, open–shorted, shorted–shorted surface configurations. Multi-modal maps obtained from...

Layer thickness and the speed of sound are important parameters for nondestructive testing applications. If one is known, other can be determined by simple time-of-flight (TOF) measurement ultrasound. However, often these both unknown. In this contribution, we examine adapt ultrasonic imaging techniques using coded excitation signals to simultaneously measure homogeneous elastic plates unknown material. Good axial resolution required thin samples. We present a new approach transmission...

Elastic waves in anisotropic media can exhibit a power flux that is not collinear with the wave vector. This has notable consequences for guided plate. Through laser-ultrasonic experiments, we evidence remarkable phenomena due to slow single-crystal silicon wafer. Waves exhibiting orthogonal their vector are identified. A pulsed line source excites these reveals packet radiated parallel line. Furthermore, there exist precisely eight plane zero flux. These so-called zero-group-velocity modes...

Transit-time flow meters need to compensate for cross-sensitivity temperature. We show that Lamb wave-based setups are less affected by An optimality criterion is derived allows tune the meter into a zero local sensitivity For this end, flow-induced change in ultrasonic transit time revisited first. While wetted piston transducer directly sensitive propagation speed, of flight systems due beam displacement. Second, effect temperature incorporated analytically. It found temperature-dependent...

Properties of isotropic plates in terms material constants and thickness are characterized by making use dispersion characteristics propagating Lamb waves. A numerical model is inversely optimized order to match curves measured laser vibrometry. This kind characterization has gained interest recent research. Improvements accuracy efficiency the optimization process therefore important steps toward an industrial application this technique nondestructive testing online monitoring. For purpose,...

The acoustoelastic effect describes the change in propagation velocities of elastic waves due to mechanical prestress and is based on geometric material nonlinearity. Models describing heavily depend knowledge third order constants (TOEC). Established acquisition methods these rely measurement bulk speeds sound analytic calculations. In this contribution, we propose an alternative method by making use dispersive character guided plates. Uniaxial tensile stress applied homogeneous metallic...

Guided wave dispersion is commonly assessed by Fourier analysis of the field along a line, resulting in frequency-wavenumber curves. In anisotropic plates, point source can generate multiple branches pertaining to same modal surface, which arise due angle between power flux and vector. We show that this phenomenon particularly pronounced near zero-group-velocity points, entailing up six contributions given direction. Stationary phase points accurately describe measurements conducted on...

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We present a semi-analytical approach to compute quasi-guided elastic wave modes in horizontally layered structures radiating into unbounded fluid or solid media. This problem is of relevance, e.g., for the simulation guided ultrasound embedded plate seismic waves soil layers over an half-space. employ formulation describe layers, thus discretizing thickness direction by means finite elements. For free layer, this technique leads well-known quadratic eigenvalue mode shapes and corresponding...

Eigenvalues of parameter-dependent quadratic eigenvalue problems form eigencurves. The critical points on these curves, where the derivative vanishes, are practical interest. A particular example is found in dispersion curves elastic waveguides, such called zero-group-velocity (ZGV) points. Recently, it was revealed that problem computing ZGV can be modeled as a multiparameter (MEP), and several numerical methods were devised. Due to their complexity, feasible only for involving small...

Electroelastic waves in piezoelectric media are widely used sensing and filtering applications. Despite extensive research, computing the guided wave dispersion remains challenging. This paper presents semi-analytical approaches based on spectral methods to efficiently reliably compute curves. We systematically assess impact of electrical boundary conditions a 128{\deg} Y-cut LiNbO3 wafer, examining open-open, open-shorted shorted-shorted surfaces configurations. Multi-modal maps obtained...

Periodic cellular structures can exhibit metamaterial properties, such as phononic band gaps. In order to detect these frequency bands of strong wave attenuation experimentally, several devices for excitation and measurement be applied. this work, piezoelectric transducers are utilized excite two additively manufactured three-dimensional structures. For the transmission factor, we compare methods. First, transmitted waves measured with same kind transducer. Second, a laser Doppler vibrometer...

Elastic waves in anisotropic media can exhibit a power flux that is not collinear with the wave vector. This has notable consequences for guided plate. Through laser-ultrasonic experiments, we evidence remarkable phenomena due to slow single crystal silicon wafer. Waves exhibiting orthogonal their vector are identified. A pulsed line source excites these reveals packet radiated parallel line. Furthermore, there exist precisely eight plane zero flux. These so-called zero-group-velocity modes...

To produce sounds, we adjust the tension of our vocal folds to shape their properties and control pitch. This efficient mechanism offers inspiration for designing reconfigurable materials adaptable soft robots. However, understanding how flexible structures respond a significant static strain is not straightforward. complexity also limits precision medical imaging when applied tensioned organs like muscles, tendons, ligaments blood vessels among others. In this article, experimentally...

Objective - Shear wave elastography has enriched ultrasound medical imaging with quantitative measurements of tissue stiffness. However, this method still suffers from some limitations due to viscoelasticity, guiding geometry or static deformations. Approach To explore these limitations, a nearly-incompressible soft elastomer strip is chosen mimic the mechanical behavior an elongated tissue. A supersonic shear scanner measures propagation waves within strip. By repeating experiment on same...