Selective mode excitation in elastic waveguides by piezoceramic actuators

et al. 2010

Smart Mater. Struct.

The article describes an omni-directional multi-element transducer for selective Lamb wave mode excitation. It is composed of several coaxial ring-shaped piezoelectric elements actuated by n-cycled sinusoidal tonebursts. Mode selection is achieved by a special choice of the time delays and the amplitudes of the input driving signals. The method for the determination of these parameters is based on strict analytical considerations. In the limiting case of the infinite number of cycles and with a sufficient number of actuators it allows to generate only a single required mode, and to completely eliminate undesirable ones. It is shown that within the range of applicability of the simplest model for the piezoelectric elements, i.e. when the actuating force can be replaced by the concentrated forces applied at the locations of the edges of an element, no time delays are needed, and the required mode of excitation is achieved only by an approprite choice of the amplitudes of the input signals.

“…with a given central circular frequency ω c = 2π/T have the frequency spectraŝ 11) and clearly hold the specified property.…”

Section: Statement Of the Problemmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Selective Lamb mode excitation by piezoelectric coaxial ring actuators

et al. 2010

Smart Mater. Struct.

“…Algorithms for selective mode excitation in a layer as well as for body wave radiation directed to required zones in a half-space have also been elaborated and implemented in computer code. In detail these results are described in [8,9,10].…”

mentioning

confidence: 95%

“…The analysis of contact interaction between a surface-bonded piezoelectric actuator and an elastic half-space was carried out, for example, in [5,6]. The case of a waveguide of finite thickness was considered in [7] and in the authors' articles [8,9,10]. A detailed recent survey of the results obtained in the field can be found in [11].…”

mentioning

confidence: 99%

“…A detailed recent survey of the results obtained in the field can be found in [11]. The presented coupled models developed in [8,9,10] use the full system of elastodynamic equations for the substrate, while the longitudinal deformation of piezoelectric strips obey the equations derived under the assumptions similar to the ones used in Kirchhoff's plate theory. At that, no any preliminary assumptions on the form of contact stresses under the actuators are made.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Resonance excitation and mode selection in smart structures with piezoelectric patch actuators

Proc Appl Math and Mech

et al. 2008

A system of piezoelectric flexible patch actuators bonded to an elastic layered substrate is considered. An integral equation based model for the smart structure under consideration has been developing. The rigorous solution to the patch-substrate dynamic contact problem extends the range of the model's utility far beyond the bounds of conventional simplified models that rely on plate, beam or shell equations for the waveguide part. The developed approach provides the possibility to reveal the effects of resonance energy radiation associated with higher modes that would be inaccessible using models accounting for the fundamental modes only. Algorithms that correctly account for the mutual wave interaction among the actuators via the host medium, for selective mode excitation in a layer as well as for body waves directed to required zones in a half-space, have also been elaborated and implemented in computer code. Electromechanical systems with distributed piezoelectric actuators and sensors in the form of flexible patches bonded to or embedded in elastic waveguide structures serve as a basis for modern material systems with intelligence and life features integrated in the microstructure that are referred to as smart materials and smart structures. They find a wide variety of applications in ultrasonic non-destructive evaluation and structural health monitoring, e.g. shell structures in aerospace units, active systems of vibration damping, precision mechanical positioning gears, ultrasonic surface wave motors etc.We consider elastodynamic behavior of substructures (layers or half-spaces) with sets of thin and flexible piezoelectric strip actuators bonded to their surface (typical configurations are shown in Fig. 1). The longitudinal deformation of the piezoelectric strips in response to a transverse electromagnetic field causes contact shear tractions generating a 2D in-plane harmonic wave field u(x, z)e −iωt in the waveguide. Conventionally, such piezoelectrically excited devices are simulated using simplified mathematical models with mechanical elements (elastic waveguides) described by beam, plate or shell equations and actuating contact forces replaced by concentrated bending moments applied at the points of patch edges (pin-force models; see, for example, surveys in [1, 2]). However, these models may be used in a low-frequency range only, first of all, because they do not account for the higher normal modes inherent to elastic layer waveguides. For instance, the comparison of the dispersion curves for an elastic layer and a Kirchhoff's plate are shown in Fig. 2). Here and in the numerical examples below ω = 2πf h/v s is a dimensionless angular frequency composed of the dimensional frequency f , waveguide's thickness h and S-wave velocity v s . The dimensionless parameters are introduced so that h = 1, v s = 1 and the material density ρ = 1; the Poisson's ratio ν = 0.3.The wave numbers ξ n of two plate traveling waves (bending and longitudinal) given in Fig. 2 by the dashed lines coincide with the wave number...

Integral equation based modeling of the interaction between piezoelectric patch actuators and an elastic substrate

et al. 2007

Smart Mater. Struct.

An integral equation based model for a system of piezoelectric flexible patch actuators bonded to an elastic substrate (layer or half-space) is developed. The rigorous solution to the patch-substrate dynamic contact problem extends the range of the model's utility far beyond the bounds of conventional models that rely on simplified plate, beam or shell equations for the waveguide part. The proposed approach provides the possibility to reveal the effects of resonance energy radiation associated with higher modes that would be inaccessible using models accounting for the fundamental modes only. Algorithms that correctly account for the mutual wave interaction among the actuators via the host medium, for selective mode excitation in a layer as well as for body waves directed to required zones in a half-space, have also been derived and implemented in computer code.