20 results about "Flexural waves" patented technology

The invention discloses an acoustic black hole structure and a vibration damping device.The acoustic black hole structure comprises an acoustic black hole body and a damping layer, the acoustic black hole body is provided with a uniform thickness area and an acoustic black hole area, the acoustic black hole area is provided with a plurality of grooves, the grooves are distributed from the first end to the second end of the acoustic black hole area, and the damping layer is arranged between the first end and the second end of the acoustic black hole area. The depths of the grooves are gradually increased in the direction from the first end to the second end, and the damping layer is arranged in the acoustic black hole area. By machining the groove in the acoustic black hole area, the local bending rigidity of the acoustic black hole body is changed, the bending wave speed of the acoustic black hole body is reduced, the acoustic black hole effect is achieved, due to the arrangement of the groove, the local resonance effect can be utilized, and then structural vibration suppression in the low-frequency range is achieved; the problem that a traditional acoustic black hole structure is poor in low-frequency-band vibration reduction effect is solved, in addition, thickness cutting of an acoustic black hole area of an original structure is avoided, and the manufacturing difficulty and the requirement for the precision of machining equipment are lowered.

Disclosed are systems for absorbing and / or isolating vibrations and / or flexural waves acting upon a structure using scatterers. In one example, a system for absorbing a flexural wave acting upon a structure includes a pair of scatterers adhered to the structure using an adhesive having a property that is based on a reduction of the flexural wave at a peak frequency by the pair of scatterers.

The application discloses a steel-concrete composite beam crack discrimination method based on bending wave structural sound intensity aggregation degree testing, which comprises the following steps: dividing a to-be-tested plate into a series of scanning areas, setting a scanning path, and calculating the bending wave structural sound intensity aggregation degree; traversing the plate according to a scanning algorithm and calculating the bending wave structural sound intensity aggregation degrees of all areas; calculating the bending wave structural sound intensity aggregation degrees of all areas of the steel-concrete composite beam plate in a service period; comparing the bending wave structural sound intensity aggregation degree spectrum peak values, and if the difference between the bending wave structural sound intensity aggregation degree spectrum peak values of a scanning area of the two exceeds a preset threshold value, it is determined that the scanning area of the steel-concrete composite beam plate in the service period has cracks. The application combines the characteristics that the bending wave signal is easy to test, adopts the bending wave structural sound intensity testing technology and the structural sound intensity aggregation degree scanning algorithm, and can realize efficient discrimination and positioning of the steel-concrete composite beam cracks, and has great theoretical significance and engineering value for damage identification of the bridge.

The invention provides an additional locally slotted acoustic black hole board, which is mounted on a main board to be damped and comprises a black hole board main body and a damping layer, the black hole board main body is fixed on the main board to be damped and comprises a uniform thickness area and one or more acoustic black hole areas, one or more weight reduction grooves are formed in the uniform thickness area, and the damping layer is arranged on the damping layer. And a damping layer is arranged on the acoustic black hole area. According to the additional type locally-slotted acoustic black hole plate, by forming the weight reducing grooves in the non-key area of an original additional acoustic black hole plate structure, redundant materials are removed, the weight reduction of an additional structure is achieved, meanwhile, the local resonance vibration reduction effect and the energy gathering capacity of the acoustic black hole effect on bending waves are kept, and the acoustic black hole plate has the advantages of being simple in structure and convenient to use. Finally, broadband vibration control of the mainboard is achieved under the low additional mass, the overall structure meets the requirement for light weight, and the structure is particularly suitable for a plate-shaped system sensitive to the additional mass.

This bending wave speaker comprises a diaphragm and an actuator that is disposed on the diaphragm and vibrates the diaphragm. The shape of the diaphragm is a parallelogram or an ellipse. When the diaphragm is a parallelogram, the ratio of the length of a first side, which is the longest side of the parallelogram, to the length in a direction perpendicular to the first side is an irrational number. When the diaphragm is an ellipse, the ratio of the major axis to the minor axis of the ellipse is an irrational number.

The application discloses a lightweight high-rigidity sandwich superstructure plate with an ultralow frequency band gap and an assembling method. The structural plate comprises a plurality of frame units arranged in a rectangular array, wherein each frame unit comprises a support frame, a base plate and a quasi-zero stiffness-inertial amplification coupled resonant unit, the support frame is connected between two base plates, and the quasi-zero stiffness-inertial amplification coupled resonant unit is arranged on the support frame and comprises a lever, a quasi-zero stiffness resonator and a mass block, the lever is hinged to the support frame, the quasi-zero stiffness resonator is located below one end of the lever and comprises a support piece, two positive stiffness elements, two negative stiffness elements and a connecting plate, the support piece is connected to the base plate, the two positive stiffness elements are vertically and symmetrically arranged at two ends of the support plate, the two negative stiffness elements are respectively connected to the inner sides of one end of the two positive stiffness elements, the mass block is connected to the other end of the lever, and the connecting plate is connected between the two negative stiffness elements, so that active control of bending wave vibration in an ultralow frequency range in engineering can be realized.

The invention relates to the technical field of mechanical structure vibration reduction and noise reduction, in particular to a low-frequency vibration isolation axial functional gradient porous beam structure and an analysis method, the structure is composed of a uniform beam area and a gradient porous beam area, the porosity in the uniform beam area section is 0, and the porosity of the gradient porous beam area section is distributed along the axial power law. The structure that the porosity changes in the axial direction in a gradient mode is adopted, the gradient change of the material characteristics (density and Young modulus) of the beam in the axial direction is achieved through the pores with the gradient change, and the energy gathering effect can be achieved through the characteristic that the impedance changes in the axial direction in a gradient mode. As vibration bending waves spread in a porous area, vibration energy is further dissipated and blocked, so that the efficient vibration reduction and isolation effect is achieved, and the situation that the weight and cost of the structure are increased due to the fact that a traditional acoustic black hole beam structure needs to be additionally laid with a viscoelastic damping material for energy absorption is avoided; and the problems of safety and use limitation caused by a gradually thinned appearance structure and the like are solved.

The application makes in-depth research on the field of sound wave front regulation in three-dimensional cases. A special acoustic lens is constructed by using a metasurface, so that the required target sound field is obtained, and the sound focusing, sound splitting and sound invisibility phenomena are realized. The research on acoustic lens is a challenging and innovative field. In the past, the research on acoustic lens was hindered by many factors such as too large material structure, complex transmission wave phase regulation and the like. The application designs a high-transmittance curved waveguide structure, and the length of the straight pipe at the neck of the curved waveguide can be adjusted to realize accurate control of the phase of the transmitted wave, and a complex internal structure is not needed. At the same time, the phase shift in the whole 2pi range can be realized by 8 basic units. Based on this, according to the theoretical calculation results, the 8 basic units are freely combined to construct a specific metasurface, so that effects such as sound focusing, acoustic lens, invisibility cloak and the like can be realized.

The invention provides an acoustic black hole structure and an acoustic black hole assembly, and belongs to the technical field of vibration noise control. The acoustic black hole structure comprises a substrate; the at least one acoustic black hole plate is located on the substrate, the acoustic black hole plate is constructed to be of an integrated gradually-shrinking structure in the thickness direction and is provided with a first surface and a second surface which face each other in the thickness direction, the sectional area of the first surface is smaller than that of the second surface, the first surface abuts against the substrate, and the second surface abuts against the substrate; a plane, which is orthogonal to the thickness direction, of the substrate is taken as a projection plane, and the projection of the second surface coincides with the projection of the substrate in the projection along the thickness direction; the damping layer is arranged on the second surface, provided with the two opposite ends in the first direction, of the acoustic black hole plate; the acoustic black hole plate is made of nonmetal. Through the combination of a non-metal material and the structure, bending waves are captured, mechanical vibration is dissipated through the arranged damping layer, and effective absorption of the bending waves in a wide frequency range is achieved.

The invention discloses a topological metamaterial for sheet bending wave isolation and a design method of the topological metamaterial. The topological metamaterial is composed of basic unit cells (1) and sheets (2). Each basic unit cell (1) comprises a regular hexagon area (1-1) and a regular triangle stand column (1-2) which are arranged on a thin plate. A topological common unit cell (3) is obtained by clockwise rotating for 0-30 degrees along the plane normal of the thin plate, and a topological non-common unit cell (4) is obtained by anticlockwise rotating for 0-30 degrees along the plane normal of the thin plate; the topological common unit cells (3) and the topological non-common unit cells (4) are alternately arranged on the thin plate (2) to form a topological metamaterial structure; the topological metamaterials arranged alternately can generate total reflection on incident thin plate bending waves, so that effective isolation of the thin plate bending waves is realized. The system has the advantages of simple design, remarkable vibration isolation effect, high expandability and the like, and is suitable for the fields of vibration prevention of building structures, vibration isolation of precise instruments, interference resistance of aerospace vehicle structures and the like.

This invention discloses a multi-directional local resonance module and its vibration-damping and isolation metamaterial tubular structure. The multi-directional local resonance module includes a matrix, a multi-directional local resonator, and a bushing ring. The multi-directional local resonator includes a triaxially adjustable elastic structure and a mass. The vibration-damping and isolation metamaterial tubular structure is composed of several multi-directional local resonance modules. The triaxially adjustable elastic structure is circumferentially distributed around the cylindrical mass and connects the mass to the bushing ring. The multi-directional local resonance modules are installed on beam or tubular matrix structures at predetermined positions via the bushing ring. This invention, through parameter design and combination design of the multi-directional local resonance modules, can achieve low-frequency, broadband, and efficient suppression of longitudinal and bending wave propagation in beam or tubular structures based on multi-directional local resonance modules, giving them strong multi-dimensional low-frequency vibration reduction and isolation capabilities in the target frequency band, and is easy to install and process.

System, methods, and other embodiments described herein relate to a high-Q resonant state embedded system in a continuous body. In one embodiment, a system includes a longitudinally extending body that is subject to a flexural wave. The longitudinally extending body is attached to a fixed structure at a first end. The system also includes a mechanical resonator coupled to a surface of the longitudinally extending body along a length dimension of the longitudinally extending body. The mechanical resonator is located at a distance away from a second end of the longitudinally extending body to exhibit an infinite Q factor based on physical properties of the mechanical resonator.

The invention relates to a combined adjustable acoustic black hole which is characterized in that the combined adjustable acoustic black hole comprises a mounting base, a plurality of acoustic black hole units and dampers, each acoustic black hole unit comprises a platform part and an energy dissipation part, the platform part and the energy dissipation part are integrally formed, and the thickness of the energy dissipation part extends outwards from the front end connected with the platform part to the tail end to be gradually thinned; the platform part is fixedly connected with mounting lugs, and the acoustic black hole units are detachably mounted on the mounting seat through the mounting lugs. The invention further discloses a using method of the combined adjustable acoustic black hole. The acoustic black hole units are mounted on the mounting seat, so that vibration waves respectively enter each acoustic black hole unit for energy gathering and dissipation during propagation, and the situation that dissipation cannot be realized due to the fact that elastic waves are transmitted to another acoustic black hole unit from the tail end is prevented. The action frequency domain can be widened through the acoustic black hole units, and the purpose of more efficient bending wave energy gathering and dissipation is achieved.

The application discloses a casing well ultrasonic bending wave logging multi-mode signal separation method, which comprises the following steps: inputting original mixed casing well ultrasonic bending wave logging data and a related parameter file; simulating A0 mode waves in the instrument centering condition; adopting a variational mode decomposition algorithm to decompose the original mixed signal into a set of multiple scale intrinsic mode functions; taking the correlation coefficient of the reconstructed A0 mode wave and the simulated standard A0 mode wave as an inversion objective function; adopting a simulated annealing method to optimize the optimal decomposition layer number and the reconstruction vector in the inversion objective function; and calculating a reconstructed A0 mode wave A' based on the optimal decomposition layer number k and the reconstruction vector v obtained by optimizing the inversion objective function. o The application can realize adaptive decomposition of A0 and S0 mode waves of a single detector in a non-axisymmetric casing well measuring environment, and can provide accurate A0 mode waves for a method for calculating wave impedance of a post-casing medium based on A0 first wave attenuation information.

Disclosed are systems and devices for absorbing flexural waves. In one example, a pair of scatterers for absorbing a flexural wave acting on a structure includes a monopole scatterer and a dipole scatterer configured to be mounted to the structure at the same location.

The invention provides an additional local slotted acoustic black hole beam, which is mounted on a structure to be damped, and comprises a black hole beam main body and a damping layer, the black hole beam main body is fixedly arranged on the structure to be damped, the black hole beam main body comprises a uniform thickness area and an acoustic black hole area which are connected with each other, one or more groups of weight reduction grooves are formed in the uniform thickness area, and the damping layer is arranged in the acoustic black hole area. The damping layer is disposed on the acoustic black hole area. According to the structure, the weight reduction grooves are formed in the non-key area of an original additional acoustic black hole beam structure, redundant materials are removed, light weight of the additional structure is achieved, meanwhile, the local resonance vibration reduction effect and the energy gathering capacity of the acoustic black hole effect on bending waves are kept, and finally broadband vibration control over the main beam is achieved under the low additional mass. And the whole structure meets the requirement for light weight, and is particularly suitable for a beam-shaped system sensitive to additional mass, and particularly suitable for vibration reduction of beam-shaped structures such as beam-shaped components in an automobile body and frame beams of aerospace vehicles.

The application discloses a honeycomb-shaped local area resonance topological insulator and an optimization design method thereof, comprising a honeycomb-shaped substrate with C-shaped openings, six pairs of oscillators with the same radius arranged on both sides of nodes, and a band gap inversion realized by changing the height difference of the oscillators, so as to construct a boundary state with different shapes. The topological transmission has backscattering suppression and channel defect immunity characteristics. Based on a particle swarm algorithm, key geometric parameters of a unit cell are optimized, and a topological insulator with a target band gap is customized. The honeycomb-shaped local area resonance topological insulator provides a new idea for flexural wave regulation, and auxiliary design is conducted in combination with a particle swarm optimization algorithm, so that the regulation range of the topological metamaterial on the flexural wave can be increased, and the vibration reduction effect can be improved.

Disclosed are systems that utilize metamaterials to improve the acoustic performance of a panel, such as a glass panel used in automotive applications. In one example, the system may include a panel having an exterior edge and a metamaterial attached adjacent to the exterior edge of the panel. The metamaterial is configured to minimize the reflection coefficient of flexural waves acting upon the panel.

Disclosed are systems and devices for absorbing flexural waves using monopole and dipole resonance. In one example, a system includes a monopole scatterer coupled to a first side of a structure at a first location and a dipole scatterer coupled to a second side of the structure at a second location that at least partially overlaps the first location. At least one of the monopole scatterer and the dipole scatterer includes a lever.

The application belongs to the field of polar acoustic measurement, and relates to a method for estimating ice layer sound velocity and thickness by using air wave and ice layer bending wave, comprising the following steps: collecting a broadband pulse sound signal by using a sensor fixed on an ice surface; recording the distance between an explosion device and the ice surface sensor; performing time-frequency analysis on the broadband pulse signal collected by the ice surface sensor; obtaining a time-frequency spectrum of the signal through the time-frequency analysis, calculating the propagation speed of the air wave, converting the time-frequency spectrum into a group velocity spectrum, and extracting a group velocity dispersion curve of the bending wave; initializing the ice layer longitudinal wave velocity, the ice layer transverse wave velocity, the ice layer thickness and the seawater sound velocity; calculating an expected group velocity curve according to an acoustic propagation model, and constructing a cost function; and optimizing the cost function by using a particle swarm algorithm, and outputting a final parameter estimation value. The application can be implemented by using only a single sensor, and does not require that a transmitting device and a receiving device be synchronized; and the ice layer sound velocity and thickness can be inverted by using the relationship between the group velocity and the acoustic parameters.