Periodic arrays of negative capacitance shunted piezoelectric patches are employed to control the band gaps of phononic beams.The location and the extent of induced band gap depend on the mismatch in impedance generat...Periodic arrays of negative capacitance shunted piezoelectric patches are employed to control the band gaps of phononic beams.The location and the extent of induced band gap depend on the mismatch in impedance generated by each patch.The total impedance mismatch is determined by the added mass and stiffness of each patch as well as the shunting electrical impedance.Therefore,the band gap of the shunted phononic beam can be actively tuned by appropriately selecting the value of negative capacitance.The control of the band gap of phononic beam with negative capacitive shunt is demonstrated numerically by employing transfer matrix method.The result reveals that using negative capacitive shunt to tune the band gap is effective.展开更多
In this paper,modified two-dimensional periodic lattice materials with local resonance phononic bandgaps are designed and investigated.The design concept isto introduce some auxiliary structures into conventional peri...In this paper,modified two-dimensional periodic lattice materials with local resonance phononic bandgaps are designed and investigated.The design concept isto introduce some auxiliary structures into conventional periodic lattice materials.Elastic wave propagation in this kindof modified two-dimensional lattice materials is studied using a combination of Bloch's theorem with finite elementmethod.The calculated frequency band structures of illustrative modified square lattice materials reveal the existenceof frequency band gaps in the low frequency region due tothe introduction of the auxiliary structures.The mechanismunderlying the occurrence of these frequency band gaps isthoroughly discussed and natural resonances of the auxiliarystructures are validated to be the origin.The effect of geometric parameters of the auxiliary structures on the width ofthe local resonance phononic band gaps is explored.Finally,a conceptual broadband vibration-insulating structure basedon the modified lattice materials is designed and its capability is demonstrated.The present work is anticipated to beuseful in designing structures which can insulate mechanicalvibrations within desired frequency ranges.展开更多
Absolute phononic band gaps can be substantially improved in two-dimensional lattices by using a symmetry reduction approach.In this paper,the propagation of elastic waves in a two-dimensional hybrid triangular lattic...Absolute phononic band gaps can be substantially improved in two-dimensional lattices by using a symmetry reduction approach.In this paper,the propagation of elastic waves in a two-dimensional hybrid triangular lattice structure consisting of stainless steel cylinders in air is investigated theoretically.The band structure is calculated with the plane wave expansion (PWE)method.The hybrid triangular Bravais lattice is formed by two kinds of triangular lattices. Different from ordinary triangular lattices,the band gap opens at low frequency(between the first and the second bands)regime because of lifting the bands degeneracy at high symmetry points of the Brillouin zone.The location and width of the band gaps can be tuned by the position of the additional rods.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.50875255 and 10902123)
文摘Periodic arrays of negative capacitance shunted piezoelectric patches are employed to control the band gaps of phononic beams.The location and the extent of induced band gap depend on the mismatch in impedance generated by each patch.The total impedance mismatch is determined by the added mass and stiffness of each patch as well as the shunting electrical impedance.Therefore,the band gap of the shunted phononic beam can be actively tuned by appropriately selecting the value of negative capacitance.The control of the band gap of phononic beam with negative capacitive shunt is demonstrated numerically by employing transfer matrix method.The result reveals that using negative capacitive shunt to tune the band gap is effective.
基金supported by the National Natural Science Foundation of China (90916007)
文摘In this paper,modified two-dimensional periodic lattice materials with local resonance phononic bandgaps are designed and investigated.The design concept isto introduce some auxiliary structures into conventional periodic lattice materials.Elastic wave propagation in this kindof modified two-dimensional lattice materials is studied using a combination of Bloch's theorem with finite elementmethod.The calculated frequency band structures of illustrative modified square lattice materials reveal the existenceof frequency band gaps in the low frequency region due tothe introduction of the auxiliary structures.The mechanismunderlying the occurrence of these frequency band gaps isthoroughly discussed and natural resonances of the auxiliarystructures are validated to be the origin.The effect of geometric parameters of the auxiliary structures on the width ofthe local resonance phononic band gaps is explored.Finally,a conceptual broadband vibration-insulating structure basedon the modified lattice materials is designed and its capability is demonstrated.The present work is anticipated to beuseful in designing structures which can insulate mechanicalvibrations within desired frequency ranges.
基金supported by the National Natural Science Foundation of China(No.10632020).
文摘Absolute phononic band gaps can be substantially improved in two-dimensional lattices by using a symmetry reduction approach.In this paper,the propagation of elastic waves in a two-dimensional hybrid triangular lattice structure consisting of stainless steel cylinders in air is investigated theoretically.The band structure is calculated with the plane wave expansion (PWE)method.The hybrid triangular Bravais lattice is formed by two kinds of triangular lattices. Different from ordinary triangular lattices,the band gap opens at low frequency(between the first and the second bands)regime because of lifting the bands degeneracy at high symmetry points of the Brillouin zone.The location and width of the band gaps can be tuned by the position of the additional rods.
