9 research outputs found
Preliminary Assessment Of A Wave Energy Conversion Principle, Using Fully Enclosed Multi-Axis Inertial Reaction Mechanisms
Low-frequency wide band-gap elastic/acoustic meta-materials using the K-damping concept
The terms "acoustic/elastic meta-materials" describe a class of periodic
structures with unit cells exhibiting local resonance. This localized resonant
structure has been shown to result in negative effective stiffness and/or mass
at frequency ranges close to these local resonances. As a result, these
structures present unusual wave propagation properties at wavelengths well
below the regime corresponding to band-gap generation based on spatial
periodicity, (i.e. "Bragg scattering"). Therefore, acoustic/elastic
meta-materials can lead to applications, especially suitable in the
low-frequency range. However, low frequency range applications of such
meta-materials require very heavy internal moving masses, as well as additional
constraints at the amplitudes of the internally oscillating locally resonating
structures, which may prohibit their practical implementation. In order to
resolve this disadvantage, the K-Damping concept will be analyzed. According to
this concept, the acoustic/elastic meta-materials are designed to include
negative stiffness elements instead or in addition to the internally resonating
added masses. This concept removes the need for the heavy locally added heavy
masses, while it simultaneously exploits the negative stiffness damping
phenomenon. Application of both Bloch's theory and the classical modal analysis
at the one-dimensional mass-in-mass lattice is analyzed and corresponding
dispersion relations are derived. The results indicate significant advantages
over the conventional mass-in-a mass lattice, such as broader band-gaps and
increased damping ratio and reveal significant potential in the proposed
solution. Preliminary feasibility analysis for seismic meta-structures and low
frequency acoustic isolation-damping confirm the strong potential and
applicability of this concept.Comment: Keywords: Acoustic meta-materials, elastic meta-materials,
low-frequency vibration absorption, seismic meta-structures, noise absorptio
Low-frequency wide band-gap elastic/acoustic metamaterials using the K-damping concept
The terms “acoustic/elastic meta-materials” describe a class of periodic structures with unit cells exhibiting local resonance. This localized resonant structure has been shown to result in negative effective stiffness and/or mass at frequency ranges close to these local resonances. As a result, these structures present unusual wave propagation properties at wavelengths well below the regime corresponding to band-gap generation based on spatial periodicity, (i.e. “Bragg scattering”). Therefore, acoustic/elastic meta-materials can lead to applications, especially suitable in the low-frequency range.
However, low frequency range applications of such meta-materials require very heavy internal moving masses, as well as additional constraints at the amplitudes of the internally oscillating locally resonating structures, which may prohibit their practical implementation.
In order to resolve this disadvantage, the KDamping concept will be analyzed. According to this concept, the acoustic/elastic meta-materials are designed to include negative stiffness elements instead or in addition to the internally resonating added masses. This concept removes the need for the heavy locally added heavy masses, while it simultaneously exploits the negative stiffness damping phenomenon.
Application of both Bloch’s theory and the classical modal analysis at the one-dimensional mass-in-mass lattice is analyzed and corresponding dispersion relations are derived. The results indicate significant advantages over the conventional mass-in-a mass lattice, such as broader band-gaps and increased damping ratio and reveal significant potential in the proposed solution. Preliminary
feasibility analysis for seismic meta-structures and low frequency acoustic isolation-damping confirm the strong potential and applicability of this concept
Fully enclosed multi-axis inertial reaction mechanisms for wave energy conversion
This paper introduces a novel concept for wave energy conversion, using fully enclosed appropriate internal body configurations, which provide inertial reaction against the motion of an external vessel. In this way, reliability, robustness and survivability under extreme weather conditions – a fundamental prerequisite for wave energy converters – can be achieved. Acting under the excitation of the waves, the external vessel is subjected to a simultaneous surge and pitch motion in all directions, ensuring maximum wave energy capture in comparison to other wave energy converters like point heave absorbers. The internal body is suspended from the external vessel body in such an appropriate geometrical configuration, that a symmetric four-bar mechanism is essentially formed. The main advantage of this suspension geometry is that a linear trajectory results for the centre of the mass of the suspended body with respect to the external vessel, enabling the introduction of a quite simple form of a Power Take Off (PTO) design. Thus, because of this simplicity and symmetry of the suspension geometry and of the PTO mechanism, the fundamental restrictions of other linear, pendulum or gyroscopic variants on inertial reacting bodies are significantly removed
Analysis and evaluation of energy converters based on multi-axis inertial reaction mechanisms
Implementation assessment of a Wave Energy Converter, based on fully enclosed multi-axis inertial reaction mechanisms
Low-frequency wide band-gap elastic/acoustic metamaterials using the K-damping concept
The terms “acoustic/elastic meta-materials” describe a class of periodic structures with unit cells exhibiting local resonance. This localized resonant structure has been shown to result in negative effective stiffness and/or mass at frequency ranges close to these local resonances. As a result, these structures present unusual wave propagation properties at wavelengths well below the regime corresponding to band-gap generation based on spatial periodicity, (i.e. “Bragg scattering”). Therefore, acoustic/elastic meta-materials can lead to applications, especially suitable in the low-frequency range.
However, low frequency range applications of such meta-materials require very heavy internal moving masses, as well as additional constraints at the amplitudes of the internally oscillating locally resonating structures, which may prohibit their practical implementation.
In order to resolve this disadvantage, the KDamping concept will be analyzed. According to this concept, the acoustic/elastic meta-materials are designed to include negative stiffness elements instead or in addition to the internally resonating added masses. This concept removes the need for the heavy locally added heavy masses, while it simultaneously exploits the negative stiffness damping phenomenon.
Application of both Bloch’s theory and the classical modal analysis at the one-dimensional mass-in-mass lattice is analyzed and corresponding dispersion relations are derived. The results indicate significant advantages over the conventional mass-in-a mass lattice, such as broader band-gaps and increased damping ratio and reveal significant potential in the proposed solution. Preliminary
feasibility analysis for seismic meta-structures and low frequency acoustic isolation-damping confirm the strong potential and applicability of this concept
Low-frequency wide band-gap elastic/acoustic metamaterials using the K-damping concept
The terms “acoustic/elastic meta-materials” describe a class of periodic structures with unit cells exhibiting local resonance. This localized resonant structure has been shown to result in negative effective stiffness and/or mass at frequency ranges close to these local resonances. As a result, these structures present unusual wave propagation properties at wavelengths well below the regime corresponding to band-gap generation based on spatial periodicity, (i.e. “Bragg scattering”). Therefore, acoustic/elastic meta-materials can lead to applications, especially suitable in the low-frequency range.However, low frequency range applications of such meta-materials require very heavy internal moving masses, as well as additional constraints at the amplitudes of the internally oscillating locally resonating structures, which may prohibit their practical implementation. In order to resolve this disadvantage, the KDamping concept will be analyzed. According to this concept, the acoustic/elastic meta-materials are designed to include negative stiffness elements instead or in addition to the internally resonating added masses. This concept removes the need for the heavy locally added heavy masses, while it simultaneously exploits the negative stiffness damping phenomenon. Application of both Bloch’s theory and the classical modal analysis at the one-dimensional mass-in-mass lattice is analyzed and corresponding dispersion relations are derived. The results indicate significant advantages over the conventional mass-in-a mass lattice, such as broader band-gaps and increased damping ratio and reveal significant potential in the proposed solution. Preliminary feasibility analysis for seismic meta-structures and low frequency acoustic isolation-damping confirm the strong potential and applicability of this concept