582 results about "Low frequency vibration" patented technology

The invention provides an unmanned aerial vehicle multi-dimensional information fusion method and system based on acousto-optic-electric composite detection. According to the method, acoustic frequency band signals, visible light image sequences and electromagnetic field intensity change data are collected, acoustic characteristic flow, optical characteristic flow and electrical characteristic flow are generated, and based on the time deviation between a low-frequency vibration mode and transient electromagnetic pulses, multi-channel dynamic calibration is carried out on an image distortion area in the optical characteristic flow. The method comprises the following steps: acquiring an acoustic feature flow, an optical feature flow and an electrical feature flow, correcting space-time coordinate parameters of the acoustic feature flow, the optical feature flow and the electrical feature flow, generating a calibration feature flow, carrying out anti-interference fusion processing on the calibration feature flow, extracting multi-dimensional coupling features, inputting the multi-dimensional coupling features into an unmanned aerial vehicle flight path planning model, and generating a three-dimensional space situation model; according to the invention, the physical space-time consistency alignment and noise suppression of the multi-modal data are realized, and the obstacle positioning precision and the dynamic trajectory prediction real-time performance are significantly improved.

The invention relates to a low-frequency vibration isolator with a wide quasi-zero stiffness interval. The low-frequency vibration isolator comprises a bearing platform, a base, a first negative stiffness assembly, a second negative stiffness assembly and a linear vibration isolation assembly. The bearing platform and the base are arranged in parallel and are both provided with bolt holes and limiting holes; a linear vibration isolation assembly is installed between the bearing platform and the base. The first negative stiffness assemblies are symmetrically distributed with the center point connecting line of the bearing platform and the base as the symmetry axis. The top of the first negative stiffness assembly is connected with the bearing platform, and the bottom of the first negative stiffness assembly is connected with the base. The two ends of the second negative stiffness assembly are connected with the two first negative stiffness assemblies correspondingly. The low-frequency vibration isolator has the characteristics of high static rigidity and low dynamic rigidity, the contradiction between the bearing capacity and the vibration isolation performance of a linear vibration isolation system is effectively solved, and the effective low-frequency vibration isolation effect on a vibration-isolated object is achieved while the bearing capacity of the vibration isolator is guaranteed.

The invention discloses a self-adaptive noise reduction method for a positive pressure type air respirator based on airflow spectrum characteristics, and relates to the technical field of positive pressure type air respirators.The self-adaptive noise reduction method comprises the steps that a respirator air path pressure signal and an environment noise signal are synchronously collected through an airflow sensor and a microphone array; performing time-frequency analysis on the collected signals, and extracting airflow spectrum features; and establishing a mapping relation between the working state of the breathing machine and the noise spectrum based on the historical record according to the mapping relation between the working state of the breathing machine and the noise spectrum. Through real-time acquisition and analysis of airflow frequency spectrum characteristics, accurate identification of useful airflow signals and environmental noise signals, dynamic adjustment of noise reduction parameters, effective suppression of high-frequency noise and low-frequency vibration, and improvement of noise reduction effect, compared with a traditional fixed frequency band filtering or passive sound insulation material, the method can better cope with a non-stationary noise environment, and has good application prospects. The noise reduction strategy is adjusted in real time, clear auditory information is provided in a complex noise environment, and therefore the auditory perception ability of firemen is improved.

The invention discloses a gravimeter active vibration isolation control method, and belongs to the technical field of gravimeter active vibration isolation, and the control method comprises the steps: S1, presetting a three-axis acceleration sensor and a gravimeter bearing platform, and detecting a space vibration signal of the gravimeter bearing platform in real time through the three-axis acceleration sensor; s2, the signal processing unit performs frequency domain decomposition on the space vibration signal; s3, establishing a feedforward control unit, a feedback control unit and a synthesis unit; s4, a multi-degree-of-freedom actuator is preset, and reverse compensation force is applied in the X-axis direction, the Y-axis direction and the Z-axis direction through the multi-degree-of-freedom actuator according to the composite control signal; and S5, the preset state monitoring unit samples the vibration suppression rates in three continuous sampling periods. The high and low frequency vibration components are dynamically divided according to the frequency-band energy accumulation proportion, the vibration interference model is established in combination with the high and low frequency vibration components, and compensation failure caused by model mismatch under complex working conditions is avoided.

The invention relates to the technical field of vibration control, and discloses a quasi-zero stiffness vibration isolator imitating an insect jumping foot structure, which comprises a base and a bearing table between which a vertical spring is arranged, the two sets of connecting rod mechanisms are arranged between the base and the bearing table, each set of connecting rod mechanism comprises two lower connecting rods, two upper connecting rods and two middle connecting rods, the two lower connecting rods are hinged to the top face of the base, the two upper connecting rods are hinged to the bottom face of the bearing table, and the two middle connecting rods are distributed in an X shape; two ends of the two middle connecting rods are respectively hinged with the lower connecting rod and the upper connecting rod; the transverse springs are arranged at the hinged positions of the two lower connecting rods and the two middle connecting rods and the hinged positions of the two upper connecting rods and the two middle connecting rods correspondingly. The vibration isolator is simple in structure, small in transverse size, convenient to assemble and disassemble and easy to adjust, quasi-zero-stiffness vibration isolation is achieved through the special mechanical property of the overall structure, vibration energy can be efficiently absorbed, and the vibration isolator has wide application prospects in the field of low-frequency vibration control.

The invention belongs to the technical field of equipment management, and particularly discloses a conveyor line motor residual life prediction method and system based on health indicators, and the method comprises the following steps: obtaining a low-frequency vibration signal of a motor; calculating a time domain feature sequence and a probability density function feature sequence; dividing a motor by using a K-means clustering algorithm to obtain a plurality of equipment groups; establishing a health index sub-model for the motors in the equipment group; performing mutual testing on the health index sub-models in the equipment group, performing smoothing processing and trend screening on health index testing results of all motors, and performing similarity integration to obtain a health index sequence; and predicting the residual life of the motor by using the health index model. According to the method, a composite feature extraction system and a dynamic integrated modeling framework oriented to a low-frequency sampling scene are constructed, the feature representation capability of field data can be improved, and the technical problem of high equipment group degradation isomerism is solved.

The invention relates to a robot multi-frequency vibration composite suppression method and system based on inertia disturbance analysis. The method comprises the steps of obtaining dynamic operation data in the operation process of a robot; the operation data are input into an inertia disturbance analysis module, and a low-frequency vibration source caused by a mechanical structure and a high-frequency vibration source caused by a driving system can be accurately recognized; a disturbance frequency distribution diagram is generated, according to the distribution diagram, a self-adaptive filtering algorithm is adopted to suppress a high-frequency vibration source, a compensation algorithm based on model prediction control is adopted to suppress a low-frequency vibration source, the two strategies are cooperatively processed to generate a comprehensive control instruction, the advantages of the two algorithms are fully played, and effective composite suppression of multi-frequency vibration is achieved.

The invention relates to a multi-machine cooperative dynamic balance driving method, system and device for a spiral lifting machine, and the method comprises the steps: carrying out the compensation of the time lag of an actuator through employing a non-linear state observation and time lag compensation combined method, and obtaining a feedforward control quantity; performing Lyapunov stability feedback processing on the vibration acceleration signal to obtain a vibration suppression control quantity; designing a multi-section S-shaped speed curve, and calculating a closed-loop feedback control quantity by adopting PID (Proportion Integration Differentiation) combined with a robust control algorithm; and according to the feedforward control quantity, the vibration suppression control quantity and the closed-loop feedback control quantity, multi-machine cooperative dynamic balance driving of the spiral lifting machine is carried out. According to the invention, a non-linear state observation and time delay compensation technology is adopted, so that the synchronization error is reduced to a millisecond level; the low-frequency vibration amplitude is reduced through dynamic feedback control designed based on the Lyapunov theory; the hydraulic impact is obviously reduced by adopting a multi-section S-shaped speed curve; external disturbance is observed in real time through Kalman filtering, feed-forward compensation is carried out, and the robustness of the system is greatly enhanced.

A power transmission line vibration energy collection device based on a triboelectricity-electromagnetic effect belongs to the technical field of power transmission line self-powered equipment, and comprises a shell, a wire clamp device, a triboelectricity unit, a vibrator structure and a cantilever beam structure, and can collect multi-frequency and multi-amplitude vibration energy of a power transmission line in the vertical direction. And the cantilever beam-magnetic coupling structure is adopted to improve the low-order modal frequency, so that the vibration frequency response range of the self-powered device is widened, and the self-powered device has the following advantages that 1, efficient low-frequency energy collection is realized, and the vibrator structure can effectively collect low-frequency vibration energy by virtue of the gravity of the vibrator structure and the action of the supporting spring; 2, the fatigue resistance is excellent, and the cantilever beam does not directly participate in excitation of the triboelectric energy harvesting unit, so that the risk of fatigue fracture of the cantilever beam is effectively reduced; and 3, the energy collection capability of the device is improved, and friction electricity energy harvesting and electromagnetic energy harvesting are combined, so that the collection efficiency of high-frequency excitation energy can be further improved.

The invention discloses a spiral air duct predictive operation and maintenance method and system based on digital twinning, and relates to the technical field of air duct system state monitoring and operation and maintenance, and the method comprises the following steps: deploying a high-frequency acoustic emission AE sensor and a low-frequency vibration acceleration sensor at key nodes of a spiral air duct, and taking a fan start-stop signal and operation power as working condition labels; a high-frequency acquisition mode is automatically triggered, noise reduction processing is carried out, and a multi-mode acoustic vibration original signal data set which is provided with a time sequence and a working condition label and is subjected to preliminary noise reduction is output; the high-frequency acoustic emission AE sensor and the low-frequency vibration acceleration sensor are arranged in the spiral duct, the health state of the thin-wall structure is monitored in real time through the high-frequency acoustic emission technology, weak early-stage fault signals in the duct can be accurately captured and early warning can be given out in the fault germination stage of fretting wear, sealant aging and the like of the spiral duct, and the fault early-warning effect is achieved. Real-time monitoring, early warning and accurate operation and maintenance of the spiral air pipe are achieved.

The invention belongs to the technical field of low-frequency vibration control, and provides a low-frequency tuned mass damping device for reversely stretching a compression spring in order to solve the problem that a traditional tuned mass damper is limited in use of a vertical space due to too large net deformation of the spring under the low-frequency condition. According to the device, large compression deformation and reverse tensile deformation of the spring are fully realized in a limited vertical space in a manner of performing super-compression-reverse tensile treatment on the compression spring, relatively low rigidity required by a vibration system is achieved, low-frequency tuning can be realized in the limited vertical space of a bridge girder, and the rigidity of the vibration system is improved. The frequency application range of the tuned mass device is greatly expanded; and meanwhile, the problems that the stability problem is caused when a traditional compression spring mass body is arranged on the spring and the damping is too high and unstable due to the fact that a guide component is added are solved. The device is simple in structure, low in damping, low in space requirement and good in stability, and can be applied to vertical, lateral and torsional multi-type low-frequency vibration control of various engineering structures.

The invention relates to the field of vehicles, and provides a local resonance damping design method and electronic equipment. The method comprises the following steps: S1, determining the resonant frequency and position of a vehicle body by analyzing the sound and vibration characteristics of the vehicle body; s2, setting an optimization constraint and an optimization target based on the determined resonant frequency, and performing optimization design on a damping structure of local resonance through first simulation software to obtain an optimized damping structure corresponding to the resonant frequency; the design parameters of the optimized damping structure at least comprise modal parameters, three-dimensional data and material parameters; s3, calculating a resonance band gap of the damping structure by using second simulation software according to the design parameters of the damping structure; s4, according to the resonance frequency of the vehicle body and the resonance band gap of the damping structure, optimization design is conducted on the damping layer; and S5, arranging the optimized damping structure and damping layer according to the analyzed vibration transmission steps. The control efficiency of low-frequency vibration can be improved, and the driving comfort of a user is guaranteed.

The invention discloses a transformer self-adaptive vibration reduction system based on a magnetorheological damper and a multi-mode cooperative control method, which are used for solving the problems of insufficient low-frequency vibration suppression and poor environmental tolerance in the prior art. The vibration reduction system comprises a sensor module, a control unit, an execution mechanism and an energy recovery module. The sensor module monitors vibration signals of a transformer iron core and a winding in real time; the control unit converts the vibration signal into a magnetic field intensity adjusting instruction in real time, and the damping force accurately matches the target demand by actively compensating disturbance and dynamically optimizing parameters; the execution mechanism comprises a dual-channel magnetorheological damper, the energy recovery module comprises a friction nanometer generator TENG and a super capacitor, the output voltage of the TENG is stored in the super capacitor after DC-DC conversion, and energy closed-loop utilization is achieved. The problems that a traditional vibration reduction device is insufficient in low-frequency suppression, prone to corrosion and high in energy consumption are solved through multi-frequency-band vibration suppression, environment self-adaption design and the self-power-supply technology.

The invention relates to the technical field of generator exhaust, and discloses a generator outlet exhaust pipe structure which comprises a connector and a vertical exhaust pipe, the bottom end of the connector is directly connected with the air outlet end of a generator, and the connector and the vertical exhaust pipe are connected through a metal bellow expansion joint. A vibration reduction component is arranged on the outer wall of the vertical exhaust pipe, and a temperature control component is arranged in the vertical exhaust pipe; the vibration reduction component comprises a fixed frame and a sliding frame, the fixed frame is connected with a wall and other fixed structures, thick springs and thin springs are used for forming a composite vibration reduction spring structure, and when the vertical exhaust pipe is subjected to low-frequency vibration, the displacement of the exhaust pipe is small, and at the moment, only the thin springs deform; when the vibration frequency rises and the displacement amount is too large, the thick spring starts to be connected with the thin spring in parallel for bearing, the variable stiffness characteristic is formed, the good vibration reduction effect is achieved, and meanwhile the damper works to absorb kinetic energy of vibration.

The invention discloses a digital stethoscope system based on a piezoelectric film, and relates to the technical field of medical electronics and biomedical engineering. An existing digital stethoscope based on a piezoelectric film has the challenges of signal noise and interference, limitation of a signal processing algorithm, nonlinear response and time migration, insufficient diagnosis accuracy and automation and the like. A piezoelectric film and microphone dual audio acquisition mode is fused, various physiological signals such as low-frequency vibration and high-quality heart and lung sound are captured, and background noise is removed through a self-adaptive filter and a frequency spectrum subtraction technology; an MFCC feature extraction and dynamic time warping algorithm is utilized to carry out fine feature analysis and time axis alignment on the preprocessed audio signal, and high-precision matching with a storage template is realized; different physiological states are accurately distinguished through intelligent feature processing, real-time and visual diagnosis feedback is achieved through wireless transmission and state indication, and the reliability and efficiency of medical detection are improved.

The utility model provides a local resonance type phononic crystal primitive cell which comprises a silicon rubber base body serving as an outer ring, a steel scatterer is arranged in an inner cavity of the silicon rubber base body, and the steel scatterer and the silicon rubber base body are connected and fixed through a soft material wrapping layer. The four spring mass subsystems are nested in the steel scattering body; a soft material wrapping layer is arranged on the side wall of the inner cavity of the silicone rubber base body. According to the utility model, a plurality of complete and directional band gaps in a low-frequency range can be effectively formed, and low-frequency elastic waves are effectively inhibited; the hollow and height difference design is adopted among the external silicon rubber base body, the steel scatterer and the spring mass subsystem, so that the vibration damping material has a sufficient deformation space to play a vibration damping role; the steel scatterer, the spring mass subsystem and other structures ensure that the anti-vibration pad has an enough supporting effect, band gap regulation and control of the local resonance type photonic crystal can be effectively achieved through material selection flexibility, and low-frequency vibration control of different frequency bands is achieved.

The invention provides a self-powered vibration sensor based on multi-mode energy capture, and the sensor comprises a multi-mode vibration energy capture unit which comprises a piezoelectric ceramic piece and an electromagnetic induction coil-permanent magnet assembly, and the piezoelectric ceramic piece and the electromagnetic induction coil-permanent magnet assembly are installed on the surface of equipment in parallel, the piezoelectric ceramic is used for capturing 100-200Hz high-frequency vibration energy; the electromagnetic induction coil-permanent magnet assembly is used for capturing low-frequency vibration energy of 5-50 Hz; the energy acquisition power supply management circuit comprises a double-path rectification filter circuit, a first bidirectional DC-DC converter and a super capacitor / lithium battery hybrid energy storage unit; the first bidirectional DC-DC converter is connected with the two-way rectification filter circuit and the super capacitor / lithium battery hybrid energy storage unit at the same time, and is used for controlling charging and discharging of the super capacitor / lithium battery hybrid energy storage unit based on a preset dynamic impedance matching network and an energy priority scheduling strategy.

The invention relates to the field of buried facility monitoring, and discloses a piezoelectric cantilever vibration sensing and super capacitor self-powered energy closed-loop operation method and system, and the method comprises the steps: building a star array composed of a master pile and a slave pile, and configuring a TDMA time slot and an uplink message length; the slave pile collects a vibration signal through a piezoelectric cantilever, the vibration signal is rectified by a piezoelectric rectification energy taking module and then charges a super capacitor, and the voltage state of the two ends of the super capacitor is obtained; when the voltage state reaches a preset upper threshold, the boosting module supplies power to the processing circuit and the transmitting circuit of the slave pile, and the processing circuit generates a four-byte feature code; the slave piles send four-byte feature codes in a magnetic induction link according to TDMA time slots, the master pile receives and aggregates the four-byte feature codes sent by the multiple slave piles, completes positioning and fusion according to the arrival time difference, and returns the four-byte feature codes to the platform through LoRa and 4G, and the platform completes storage and output according to the four-byte feature codes and a positioning result. According to the invention, end-side cloud connection and replicable deployment can be realized, and low-frequency vibration acquisition and buried communication are adapted.

The utility model relates to the technical field of vehicle signal devices, and provides a vehicle-mounted loudspeaker mounting structure and a vehicle. The vehicle-mounted loudspeaker mounting structure is used for mounting a vehicle-mounted loudspeaker on a vehicle body and comprises a mounting base body provided with the vehicle-mounted loudspeaker, a connecting assembly and a damping assembly. The connecting assembly comprises a connecting piece for connecting the mounting base body and a vehicle body; the damping assembly comprises a damping bush arranged on the connecting piece in a sleeving mode and a supporting bush located between the damping bush and the connecting piece. The vehicle-mounted loudspeaker mounting structure not only has better structural stability and is beneficial to ensuring the mounting reliability of the vehicle-mounted loudspeaker, but also can absorb high and low frequency vibration generated when the vehicle-mounted loudspeaker works and reduce adverse effects caused by vibration of the vehicle-mounted loudspeaker, thereby being beneficial to improving the driving comfort and the driving safety coefficient.

A high-vibration-resistance AGM battery shell structure comprises a battery groove body, the battery groove body is of a cuboid structure with an opening in the upper portion, a groove body inner cavity is composed of a bottom plate and side plates erected on the bottom plate, and the side plates comprise the front side plate and the rear side plate which are arranged in the length direction and the left side plate and the right side plate which are arranged in the width direction; an inner cavity of the tank body is divided into a plurality of unit cells which are the same in size and are used for assembling a plate group of the storage battery by partition walls; reinforcing frames are arranged on the peripheries of the outer side faces of the front side plate, the rear side plate, the left side plate and the right side plate, and honeycomb grids fully covered in the reinforcing frames form a honeycomb structure. Each honeycomb lattice comprises a hexagonal pyramid frustum structure, the lattice bottom is closed, and the lattice opening is open. By designing the battery jar body with the honeycomb structure, low-frequency vibration energy in the running process of a vehicle can be effectively absorbed, various stresses under the low-frequency vibration condition can be dispersed, and resonance can be reduced, so that the vibration resistance of the storage battery can be improved, and a pole group in the storage battery can be effectively prevented from being damaged by vibration.

The invention discloses an electromagnetic energy collection device based on multi-stage gear clutch transmission, and belongs to the technical field of new energy collection, and the device comprises a gear set which is used for converting external axial excitation into rotation kinetic energy and accelerating the rotation frequency; a power generation module; the device comprises a magnet flywheel meshed with a gear set and multiple sets of magnet-coil pairing units, magnets are fixedly installed on the magnet flywheel, the magnet flywheel is driven by the gear set to rotate, the magnets rotate, the coils cut magnetic induction lines generated by the magnets, and rotation kinetic energy is converted into electric energy; the elastic reset system is used for realizing separation and reunion of a gear set and the power generation module through an elastic reset gear set, so that continuous power generation is realized; by means of multi-stage gear acceleration and a gear-sliding groove one-way torque coupling mechanism, efficient and continuous conversion from axial low-frequency vibration energy to electric energy is achieved, and the device is small in overall size and suitable for the fields such as bridges and industrial equipment which have strict requirements for low-frequency energy collection.

The invention relates to the technical field of waste battery recycling, in particular to a battery module lossless disassembling method based on low-temperature brittleness difference, which comprises the following steps: step 1, analyzing material brittleness and formulating a gradient cooling program; 2, local directional cooling and embrittlement control, wherein a low-temperature cooling medium is adopted to conduct directional spraying on the adhesive concentration area, and meanwhile the temperature of the metal current collector is maintained to be higher than the embrittlement temperature of the metal current collector through heat insulation protection; temperature distribution is monitored in real time, cooling parameters are dynamically adjusted, and it is ensured that a target material is completely embrittled; step 3, vibration separation and layered recovery: applying low-frequency vibration to the embrittled battery module to break the embrittled material layer; and sorting materials based on fragment size and density difference, and recovering the complete metal current collector. By means of the steps, it is guaranteed that materials are not damaged in the disassembling process, and lossless disassembling and efficient recycling of the battery module are achieved through accurate control and the efficient sorting process.

The invention discloses a quasi-zero stiffness electromagnetic-spring-rubber composite vibration isolator with a wide vibration isolation frequency band. The quasi-zero stiffness electromagnetic-spring-rubber composite vibration isolator comprises a vibration isolator shell. The electromagnetic structure core is installed in the vibration isolator shell and comprises a first coil, an annular permanent magnet, a third coil and a second coil which are sequentially arranged from top to bottom, the current direction of the first coil is the same as that of the second coil, and the current direction of the third coil is opposite to that of the second coil; the rubber-spring composite vibration isolation platform is mounted in the vibration isolator shell, and the rubber-spring composite vibration isolation platform is mounted in the vibration isolator shell; high linear positive stiffness provided for the rubber-spring composite vibration isolation platform through an electromagnetic structure core is combined with linear negative stiffness provided for the rubber-spring composite vibration isolation platform, a quasi-zero-stiffness platform with small stiffness and large range is achieved, low-frequency vibration with large amplitude can be isolated, the rubber vibration isolation platform is combined, and the vibration isolation performance of the rubber-spring composite vibration isolation platform is improved. And vibration isolation of a wide vibration isolation frequency band is realized.

The invention discloses a foldable piezoelectric vibration energy collector, and the collector comprises a cantilever beam which is provided with a fixed end at one end and a free end at the other end; the mass block is located below the cantilever beam, fixedly connected with the free end and used for adjusting the resonant frequency of the cantilever beam; the piezoelectric element is arranged on the cantilever beam; when the cantilever beam vibrates in the vertical direction, the piezoelectric element generates electric energy; the electric energy collecting element is electrically connected with the piezoelectric element and is used for collecting the electric energy; wherein the piezoelectric element comprises a plurality of piezoelectric layers, the plurality of piezoelectric layers are distributed at intervals in the vertical direction and are arranged in parallel, and every two adjacent piezoelectric layers are fixedly connected. Under the condition that a larger mass block or a longer cantilever beam does not need to be arranged, the energy conversion efficiency of the piezoelectric vibration energy collector in an ultralow-frequency vibration environment can be improved, and the miniaturization and wearable requirements of devices or electronic equipment can be met.

The invention relates to the technical field of shock absorption, and discloses a frequency self-adaptive shock absorber which comprises a cylinder body, a piston assembly and a frequency response structure. The piston assembly comprises a piston body and a piston rod. The frequency response structure is integrated in the piston rod and comprises a communicating channel, a mounting hole, an adjusting rod, an elastic piece and a plunger sleeve, the plunger sleeve is arranged in the communicating channel, a conical convex part is arranged at one end of the adjusting rod, an overflowing gap is formed between the peripheral face of the conical convex part and a port of the plunger sleeve, and the elastic piece is connected with the end, deviating from the plunger sleeve, of the adjusting rod. The frequency response structure is integrated in the piston rod, the elastic piece made of the nonlinear elastic material is used for sensing the oil pressure frequency change, the adjusting rod is driven to move in combination with the oil pressure, the damping force can be reduced at high frequency and increased at low frequency, and self-adaptive adjustment of the damping force of the shock absorber under high and low frequency vibration road conditions is achieved. According to the design, a complex frequency control valve does not need to be additionally arranged, and the cost, the structural complexity and the overall size of the damper can be remarkably reduced.

A fixed-wing aircraft flutter excitation and testing system and method. The fixed-wing aircraft flutter excitation and testing system comprises an excitation apparatus and a testing system; the excitation apparatus comprises miniature excitation rockets arranged at excitation points of wingtips of elastic structures on an aircraft, and an ignition control system electrically connected to the miniature excitation rockets; the testing system comprises an airborne signal acquisition subsystem and a vibration signal acquisition subsystem; the airborne signal acquisition subsystem comprises a data acquisition recorder and a GPS antenna, and is used for recording flight state parameters and GPS time of the aircraft; and the vibration signal acquisition subsystem comprises low-frequency vibration acceleration sensors arranged at testing points of rigid planes of the elastic structures on the aircraft, and a data acquisition recorder. According to the fixed-wing aircraft flutter excitation and testing system and method, various flutter modes can be accurately, conveniently and efficiently obtained by means of the excitation apparatus, and flight state parameters and vibration parameters required for flutter analysis are obtained by means of the testing system.

The invention belongs to the technical field of vibration isolation, and particularly relates to a quasi-zero stiffness metamaterial sandwich structure, a vibration isolation device and a manufacturing method. The quasi-zero stiffness metamaterial sandwich structure is formed by periodically arranging unit cells in the horizontal direction, and each unit cell comprises an upper panel, a lower panel, a QZS resonator core body and a vertical supporting column; the QZS resonator core comprises a central mass block, QZS resonator units are arranged on the upper portion and the lower portion of the central mass block in a mirroring mode, each QZS resonator unit is composed of two quasi-zero-stiffness unit cells which are arranged in a crossed mode, and each quasi-zero-stiffness unit cell is composed of a negative-stiffness component comprising a horizontal curved beam and a positive-stiffness component comprising an oblique straight beam. According to the sandwich structure, the quasi-zero-stiffness resonator of a novel structure serves as a core body, wider application in the ultra-low frequency vibration reduction field can be achieved, the band gap is adjustable, and the problems that a traditional metal base material structure is high in band gap frequency and limited in application field can be solved.

The invention discloses a physical information network-based local resonance topology metamaterial reverse design method, and relates to the field of design, optimization and application of elastic metamaterials, and the method comprises the steps: designing a unit cell structure based on a local resonance principle, and building a frequency dispersion relation data set of the unit cell structure; establishing a finite element equivalent model, and calculating the local resonance frequency of an oscillator in the unit cell structure; constructing a physical information neural network based on the unit cell structure and the finite element equivalent model, and constructing a topological metamaterial reverse design model by using the physical information neural network; and on the basis of sample data in the data set, constructing low-frequency broadband target frequency dispersion characteristics by performing linear transformation on the frequency dispersion relationship, and importing the target frequency dispersion characteristics into the reverse design model to realize topological metamaterial structure design. Through an innovative reverse design method, vibration control of a specific target frequency band in a low-frequency range can be realized, and the method is particularly suitable for low and medium frequency vibration suppression requirements of high-precision equipment such as a precision instrument working platform and a precision equipment vibration isolation base.

The invention discloses a cold atom interference type low-frequency vibration measurement device and a measurement method, and solves the problems that the existing cold atom interference gravimeter measurement equipment is limited by the performance of a vibration sensor, the compensation precision is insufficient, timing calibration is needed, and the measurement precision is low. And measurement errors generated by gravity and ultralow-frequency vibration cannot be effectively separated from a measurement result of the cold atom interference gravimeter, namely, decoupling of two measurement parameters is realized, and cold atom interference measurement of low-frequency vibration is realized. The measuring device comprises a Raman laser output system, a vacuum cavity, a sensitive axis converter and a vibration detection reflecting mirror, the Raman laser output system outputs two pieces of Raman laser which have the same polarization state and are both circular polarization states; the low-frequency vibration is transmitted to the liquid crystal phase modulator through the vacuum cavity for polarization state conversion, and then is reflected to the liquid crystal phase modulator or the vibration detection reflector through the polarization splitting prism, so that the interference type low-frequency vibration of the cold atoms is measured, and decoupling of the two is realized.

Anti-vibration units are provided for vibration suppression in multiple directions. The anti-vibration units may have an X-shaped structure as part of its support structure. The anti-vibration units can work for ultra-low frequency vibration isolation in three directions in a passive manner. The anti-vibration units can achieve a flexible nonlinear stiffness, which contains zero or quasi-zero stiffness, negative stiffness and positive stiffness. A smooth multi-equilibria state is also achievable. Compared with traditional spring-mass-damper (SMD) and typical QZS systems, the provided anti-vibration units can have an enhanced QZS range of larger stroke with guaranteed loading capacity, and can also achieve a lower resonant frequency with a lower resonant peak. At least some embodiments of the anti-vibration units may include a new and innovative arrangement of components that enables a more compact design than typical anti-vibration systems.