A local resonance-based impact-resistant quasi-zero stiffness superstructure device

Abstract

This invention discloses a localized resonance-based impact-resistant quasi-zero stiffness superstructure device, comprising a mass unit, pendulums, a connecting shaft, and connecting rods. The mass unit has grooves in the center of its upper, lower, left, and right surfaces, and two cross-arranged connecting rods are installed in these grooves. The connecting rods are hinged to the mass unit via connecting shafts installed in connecting holes, forming an assembly with quasi-zero stiffness characteristics. Two parallel pendulums are hinged to the grooves on the front of each mass unit. The pendulums can swing left and right or vibrate perpendicular to the plane of the device, forming a localized resonance assembly. The assemblies are interconnected to form a localized resonance-based impact-resistant quasi-zero stiffness superstructure. This invention's device has a certain degree of versatility and can meet the impact resistance requirements of various structures and devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of artificial mechanical superstructure and supermaterial technology, and particularly relates to a local resonance type anti-impact quasi-zero stiffness mechanical superstructure device. BACKGROUND

[0002] Mechanical superstructure and supermaterial is a kind of periodic artificial material with mechanical properties beyond natural materials, which can exhibit new wave mechanical properties such as band gap, negative refraction and wave invisibility. Among them, the band gap property is one of the most widely used properties, and waves and vibrations cannot propagate in the frequency range of the forbidden band, so mechanical superstructure and supermaterial can be used in vibration isolation and noise reduction, impact resistance and other fields.

[0003] Impact brings convenience to people in information transmission, production and processing, but also brings adverse effects such as structural vibration and deformation, noise pollution. Impact damage is a common form of damage in engineering structures, which mainly causes the failure of engineering structures or the malfunction of instruments caused by waves induced by impact. Common impact damages include precision instrument failure, car collision, gun shooting and other forms. How to better prevent impact damage and stop the propagation of impact energy to protect engineering structures and maintain the normal operation of instruments and equipment has wide engineering value.

[0004] The quasi-zero stiffness device can obtain high static and low dynamic stiffness characteristics. High static stiffness enables the structure to maintain high carrying capacity, and low dynamic stiffness enables the structure to maintain very low natural frequency. This kind of device used in impact protection engineering not only can maintain high structural strength and stability, but also has a wide low-frequency band gap, which can prevent the propagation of low-frequency vibration and wave caused by impact. The local resonance characteristic utilizes the resonance frequency of the resonance unit close to the frequency of elastic wave to couple with it for energy dissipation, thereby preventing the propagation of elastic wave. Superimposing two excellent performances can achieve better impact resistance effect, which has good practical value for impact protection of engineering structures. SUMMARY

[0005] The purpose of the present application is to overcome the deficiencies in the prior art, and since the impact protection of engineering structures requires a novel design concept and excellent overall performance, the present application combines the quasi-zero stiffness characteristics and the local resonance mechanism of two novel design concepts to design a local resonance type anti-impact quasi-zero stiffness mechanical superstructure device. It can effectively resist in-plane and out-of-plane impact, and has wide engineering application value.

[0006] The purpose of the present application is achieved by the following technical solutions:

[0007] The application discloses a kind of local resonance form impact resistance quasi-zero stiffness superstructure, including mass unit and connecting rod, further including pendulum and connecting shaft, the mass unit is cuboid structure, middle of six surfaces of the mass unit is equipped with rectangular groove passing through surface, wherein the rectangular groove on left and right two surfaces is perpendicular to the rectangular groove on front and back surface;Each side wall of the rectangular groove is equipped with circular through hole;The cross section of the connecting rod is rectangular, and the two ends of the connecting rod are symmetrically provided with connecting hole matched with the circular through hole;The pendulum is composed of two parts of pendulum rod and pendulum ball, one end of the pendulum rod is provided with connecting hole, and the other end is provided with pendulum ball;The cross section of the connecting shaft is circular, and includes two kinds of long and short types;Two pendulums are hinged in the rectangular groove of the front surface of the mass unit, and two connecting rods are movably connected in the rectangular grooves of the upper, lower, left and right four surfaces of the mass unit through the connecting shaft, connecting hole and circular through hole;Two mutually intersecting connecting rods are used to connect two mass units.

[0008] Further, the connecting rod includes vertical connecting rod and horizontal connecting rod, the horizontal connecting rod is used for connecting the mass units in X, Y plane, and the vertical connecting rod is used for connecting the mass units in Z direction.

[0009] Further, one end of the pendulum rod is provided with a circular connecting hole, and the pendulum is installed in the rectangular groove through the circular connecting hole and the connecting shaft.

[0010] Further, the mass units are connected by two intersecting connecting rods through the connecting shaft, and the connecting part can only rotate around one rotation degree of freedom, so as to form quasi-zero stiffness characteristics.

[0011] Further, the mass of the pendulum is smaller than the mass of the mass unit, and the stiffness of the pendulum rod is smaller than the stiffness of the mass unit;The pendulum ball of each pendulum serves as a local oscillator of the mass unit, and when there is an impact load parallel to the direction of the pendulum rod, the pendulum ball can vibrate locally, so that the quasi-zero stiffness superstructure has local resonance characteristics, and can inhibit the propagation of impact with a Gaussian pulse frequency in the range of 400Hz to 1800Hz in the structure;When subjected to in-plane impact, the pendulum can also dissipate impact energy by left and right swinging, to avoid the harm caused by in-plane impact.

[0012] Further, the mass unit, the pendulum and the connecting rod are connected by the connecting shaft, the mass unit, the pendulum and the connecting rod are arranged in a square pattern in the plane, and two pendulums are installed on the front surface of each mass unit, so as to form a mechanical superstructure with quasi-zero stiffness characteristics and local resonance characteristics.

[0013] Compared with the prior art, the technical scheme of the application has the following beneficial effects:

[0014] 1. The local resonance form of the impact-resistant quasi-zero stiffness superstructure device of the application compared with the existing quasi-zero stiffness impact-resistant device, the design is simple, and there is no need to design complex positive stiffness and negative stiffness elements for quasi-zero stiffness characteristics; the structure is simple, easy to process, manufacture and assemble, and only the connecting shaft is needed to connect other elements.

[0015] 2. The device of the application is installed with two identical pendulums on the front of each mass unit, which are hinged together with the mass unit through a connecting shaft. When subjected to external impact, the pendulum can swing left and right, and also vibrate up and down along the axis direction of the pendulum rod. The left and right swing of the pendulum can effectively resist the influence of in-plane impact, and the up and down vibration of the pendulum can assist in resisting the influence of out-of-plane impact on the protected structural devices.

[0016] 3. The mass unit and connecting rod in the device of the application are hinged with a connecting shaft, which constrains three translational degrees of freedom and two rotational degrees of freedom of the mass unit, thereby realizing a zero rotational stiffness, and the overall structure constitutes an impact-resistant quasi-zero stiffness superstructure device.

[0017] 4. The device of the application is designed based on the local resonance mechanism, and can achieve good resistance effect to impact load. The device of the application can resist impact of different Gaussian pulse frequencies by adjusting the mass of the pendulum part of the pendulum or the stiffness of the pendulum rod.

[0018] 5. The device of the application can adjust the materials, shapes and sizes of the mass unit, connecting rod and pendulum to meet various impact-resistant requirements of actual engineering, and can also determine the position and structure unit cell number of the device of the application according to the possible impact source direction, size and possible impacted area. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 The structure schematic diagram of the local resonance form of the impact-resistant quasi-zero stiffness superstructure device of the embodiment of the application is provided.

[0020] Figure 2 The connection schematic diagram between adjacent mass units of the device of the embodiment of the application is provided.

[0021] Figure 3 The explosion structure schematic diagram between the single mass unit and each component of the device of the embodiment of the application is provided.

[0022] Figure 4 The time domain response diagram of the center position mass unit of the device of the embodiment of the application is provided.

[0023] Figure 5 The time domain response diagram of the mass unit near the center of the device of the embodiment of the application is provided.

[0024] Figure 6Time domain response diagram of a quality unit of a boundary position of the device of the embodiment of the present application.

[0025] Figure 7 Time domain response diagram of a quality unit of a boundary center position of the device of the embodiment of the present application.

[0026] Figures: 1-quality unit, 2-rocker, 3-pendulum ball, 4-elongated connecting shaft, 5-transverse connecting rod connecting hole, 6-vertical connecting rod connecting hole, 7-short thick connecting shaft, 8-vertical connecting rod, 9-transverse connecting rod, 10-connecting hole. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0028] The specific embodiments and features will be described in detail below in conjunction with the schematic diagrams in the examples, and the same or similar reference signs and names in the drawings represent structural elements with the same type of function or shape. The embodiments described by reference to the drawings are exemplary and are only used to explain the present application and cannot limit the scope of the present application.

[0029] The present application provides a local resonance type anti-impact quasi-zero stiffness superstructure device, which is composed of a quality unit and a connecting rod to have a quasi-zero stiffness component, and a rocker and a pendulum ball to have a local resonance component. The device is simple and compact, easy to manufacture and install, and can produce good attenuation effect on impact loads with high impact energy range, and can meet the anti-impact requirements of various engineering environments.

[0030] The implementation scheme of the local resonance type anti-impact quasi-zero stiffness superstructure device of the embodiment of the present application is as follows: the quality units distributed at the four corners of the device are constrained in the form of fixed ends, an impact load perpendicular to the plane of the device is applied near one corner to make it vibrate, and the signals of the impact wave are detected at different positions of the superstructure of the present application. Due to the quasi-zero stiffness and local resonance characteristics of the mechanical superstructure device, the signals of the impact wave detected at different positions of the device will have different degrees of obvious attenuation.

[0031] The local resonance type anti-impact quasi-zero stiffness superstructure device provided by the embodiment of the present application is as shown in Figure 1 Fig. 1, which is composed of a quality unit 1, a pendulum ball, a connecting rod and a connecting shaft connected together in a hinged manner, wherein the quality unit and the connecting rod form a quasi-zero stiffness component, and the pendulum ball part forms a local resonance component, and the whole structure constitutes a local resonance type quasi-zero stiffness superstructure.

[0032] Figure 2The assembling diagram of the adjacent mass units of the embodiment of the present application. Four mass units can be connected through the four symmetrical sides of each mass unit 1, and the horizontal connecting rod 9 can be installed in the left and right rectangular grooves of the mass unit 1. The two ends of the horizontal connecting rod 9 are symmetrically provided with circular through holes with the same diameter, and the grooves of the mass unit are also correspondingly provided with circular holes with the same diameter, i.e. the horizontal connecting rod connecting hole 5 and the vertical connecting rod connecting hole 6; the horizontal connecting rod 9 and the mass unit 1 can be hinged together by installing the thick connecting shaft 7 in the connecting hole 10. The vertical connecting rod 8 can also be installed in the grooves on the upper and lower surfaces of the mass unit 1 by using the thick connecting shaft 7, so as to be hinged together. The adjacent mass units are connected through two intersecting connecting rods, and all the elements are arranged and assembled in sequence in the vertical and horizontal directions to form a quasi-zero stiffness superstructure.

[0033] Figure 3 The explosion structure diagram of the single mass unit and the components between the mass units of the embodiment of the present application, including the mass unit 1, the pendulum, the connecting rod and the connecting shaft. The front surface of the mass unit 1 of the embodiment is provided with a rectangular groove, and two small semi-circular holes are arranged in the groove. The pendulum rod 2 of the pendulum is hinged in the semi-circular hole through the slender connecting shaft 4 and can rotate around the connecting shaft. The lower half pendulum ball 3 of the pendulum is suspended at the other end of the pendulum rod 2, and the pendulum formed by the pendulum rod 2 and the pendulum ball 3 forms a local resonance assembly. The four sides of the mass unit are provided with grooves, and connecting holes are arranged in the grooves for hinging with adjacent mass units. In the embodiment, the side length of the mass unit is 30 mm, and the radius of the pendulum ball is 10 mm. Other parameters such as the width and depth of the groove, the length, width and thickness of the connecting rod and the pendulum rod can be freely set according to the distance between the mass units 1, and the diameters of the connecting holes and the connecting shaft are matched.

[0034] The specific technical scheme of the local resonance type impact-resistant quasi-zero stiffness superstructure provided in the above embodiment is as follows: the device of the embodiment is studied by using the finite element method. The device of the embodiment is a quasi-zero stiffness superstructure device arranged in a square shape with 10*10. Fixed constraints are applied to the four corners of the device. An impact load perpendicular to the plane of the device is applied near one of the corners of the device, and impact propagation signals are collected at other positions of the device of the present application, and the attenuation degree of the impact load at different positions of the device of the present application is recorded. The time of the applied impact excitation is 0.1s, and the impact excitation makes the impacted mass unit obtain a speed of 40mm / s.

[0035] Figure 4The time domain response graph of the device center position quality unit is provided for the embodiment of the present application, the horizontal coordinate represents time, and the vertical coordinate represents amplitude. The solid line in the figure represents the impact signal collected at the center position of the device when the front of the quality unit is not connected with the pendulum; and the dashed line represents the impact signal at the center position of the device when two pendulums are connected in the groove on the front of each quality unit. It is observed that when the pendulum is not installed, the maximum amplitude is close to 15 mm, and after the pendulum is installed, the amplitude of the quality unit at this position is reduced to within 5 mm, and the amplitude is close to zero after 30 s. It is shown that when the impact signal propagates to this position, there is already a great attenuation. It can be considered to install the protected object at this position and the position farther away from the impact source after this position.

[0036] Figure 5 The time domain response graph of the quality unit near the center of the device is provided for the embodiment of the present application. The solid line in the figure represents the amplitude when the pendulum is not installed on the front of the quality unit, and the dashed line represents the amplitude when the pendulum is installed on the front of the quality unit. Before 30 s, the amplitude when the pendulum is installed on the front of the quality unit and the amplitude when the pendulum is not installed are both below 10 mm, and the amplitude when the pendulum is installed is obviously smaller than the amplitude when the pendulum is not installed, which shows that there is also a good impact resistance effect at this position. After 30 s, the amplitude at this position when the pendulum is installed tends to be stable. This position and the position farther away from the impact source after this position are ideal anti-impact positions, and the objects with not very high anti-impact requirements can be placed in these positions.

[0037] Figure 6 The time domain response graph of the quality unit at the position near the boundary of the device is provided for the embodiment of the present application. The solid line in the figure represents the amplitude when the pendulum is not installed in the groove on the front of the quality unit, and the dashed line represents the amplitude when two pendulums are installed in the groove on the front of the quality unit. Regardless of whether the pendulum is installed on the front of the quality unit, the amplitude at this position gradually decreases with time. The amplitude when the pendulum is installed is always smaller than the amplitude when the pendulum is not installed.

[0038] Figure 7 The time domain response graph of the quality unit at the boundary center near the impact position of the device is provided for the embodiment of the present application. It can be seen that the amplitude at this position is the largest when the pendulum is not installed, compared with the previous three positions, which is not conducive to placing the protected object. However, after the pendulum is installed, the amplitude at this position quickly tends to be stable and rapidly decreases. Since this position is on the boundary of the device, it is not recommended to install the protected object at this position. The above results verify the excellent resistance of the proposed anti-impact quasi-zero stiffness superstructure device to impact load.

[0039] In summary, the application relates to a kind of local resonance form impact resistance quasi-zero stiffness superstructure device.Based on the excellent performance of quasi-zero stiffness design and the design idea that local oscillator can reduce vibration, using mass unit, connecting rod, pendulum and connecting shaft periodic arrangement assembly, form a kind of excellent performance of impact resistance mechanical superstructure.The mass unit is connected by two connecting rods, and forms quasi-zero stiffness structure;The front of each mass unit will be connected with two pendulums, under the action of impact load perpendicular to the plane, two pendulums are regarded as local oscillator, and can well inhibit the propagation of impact vibration of Gaussian pulse frequency in the range of 400Hz to 1800Hz.It is worth mentioning that when impacted in plane, the pendulum installed on the front of mass unit can also consume impact energy by swinging left and right.The embodiment of the application has strong attenuation ability to impact load in a certain impact energy range, and can be installed around the impact protection object to resist impact load along the plane or out of plane of the device.

[0040] The specific embodiments described above can be adjusted by adjusting the material parameters and structural geometric parameters of the mass unit, pendulum, connecting rod and connecting shaft in the device, as well as the number of rows and columns of the overall structure, to meet the strength and impact resistance requirements of the local resonance form impact resistance quasi-zero stiffness superstructure under different working conditions.Although the finite element method is used in the embodiment to mainly show the impact resistance performance of several typical positions in the device, the time domain signals of other positions also have obvious attenuation.

[0041] Those skilled in the art should understand that the modules or technical solutions in the drawings are not necessarily necessary for implementing the application, and the embodiments described in the specific embodiments are only one embodiment of the device of the application.The wording used in the specification does not exclude other description forms, and ordinary skilled persons can select the schemes and modules in it without creative labor.

[0042] The above description of the specific embodiments is intended to describe and illustrate the technical solutions of the application, and is not limiting.The ordinary skilled person in the art can make many equivalent changes and modifications within the scope of the application without departing from the purpose, principles and scope of the claims, and these changes and modifications are all within the protection scope of the application.

Claims

1. A locally resonant form of impact resistant quasi-zero stiffness metamaterial device comprising mass elements and links, characterised in that, The pendulum and the connecting shaft are further included, the mass unit is a cuboid structure, a rectangular groove penetrating a surface is arranged in the middle of each of six surfaces of the mass unit, the rectangular grooves on the left and right surfaces are perpendicular to the rectangular grooves on the front and back surfaces; a circular through hole is arranged on the side wall of each rectangular groove; the cross section of the connecting rod is rectangular, and the two ends of the connecting rod are symmetrically provided with connecting holes matched with the circular through holes; the pendulum is composed of a pendulum rod and a pendulum ball, one end of the pendulum rod is provided with a connecting hole, and the other end is provided with the pendulum ball; the cross section of the connecting shaft is circular, and includes two types of long and thick; two pendulums are hinged in the rectangular groove of the front surface of the mass unit, and two connecting rods are movably connected in the rectangular grooves of the upper, lower, left and right surfaces of the mass unit through the connecting shaft, the connecting hole and the circular through hole; two connecting rods arranged in cross are arranged between two mass units. The connecting rod includes a vertical connecting rod and a horizontal connecting rod, the horizontal connecting rod is used for connecting the mass units in the X and Y planes, and the vertical connecting rod is used for connecting the mass units in the Z direction; One end of the pendulum rod is provided with a circular connecting hole, and the pendulum is installed in the rectangular groove through the circular connecting hole and the connecting shaft; The mass units are connected by two cross connecting rods through the connecting shaft, and the connecting position can only rotate around one rotation degree of freedom, thereby forming a quasi-zero stiffness characteristic; The mass of the pendulum is less than the mass of the mass unit, and the stiffness of the pendulum rod is less than the stiffness of the mass unit; the pendulum ball of each pendulum serves as a local oscillator of the mass unit, when there is an impact load parallel to the direction of the pendulum rod, the pendulum ball can vibrate locally, at this time, the quasi-zero stiffness mechanical superstructure has a local resonance characteristic, and can inhibit the propagation of impact with a Gaussian pulse frequency in the range of 400 Hz to 1800 Hz; when subjected to in-plane impact, the pendulum can also dissipate impact energy through left and right swinging to avoid the harm caused by in-plane impact; The mass unit, the pendulum and the connecting rod are connected by the connecting shaft, the mass unit, the pendulum and the connecting rod are periodically arranged in a square pattern in the plane, and two pendulums are installed on the front surface of each mass unit, thereby forming a mechanical superstructure with quasi-zero stiffness and local resonance characteristics.

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