An impact-resistant covering layer using origami structure, design method and application thereof

Abstract

The present invention discloses an impact-resistant covering layer using an origami structure, a design method and an application thereof, and belongs to the technical field of impact-resistant structure design, including: S1, constructing a kinematic model of a WO covering layer and a potential energy change model of a WO covering layer according to the angle change of the dihedral angles corresponding to the peak creases and valley creases in the folding process of a WO structure; S2, selecting the length l of the valley crease and the folding degree φ of the WO structure as design parameters, and designing an impact-resistant covering layer based on a WO structure; wherein the WO structure is prepared using a shape memory material, and the shape memory material maintains isotropy in the three directions of x, y, and z in a global coordinate system, and has the same mechanical properties. The present invention adopts the above-mentioned impact-resistant covering layer using an origami structure, a design method and an application thereof, wherein the covering layer is a stacked origami-type structure, and has a large amount of space inside, which can be used for structural folding and unfolding. When an external load acts on the surface of the covering layer, its energy will be quickly transferred to the WO structure to cause it to deform, thereby dissipating energy.

Description

Technical Field

[0001] The invention relates to the technical field of impact-resistant structure design, and in particular to an impact-resistant covering layer adopting an origami structure, a design method and an application thereof. Background Art

[0002] Impact-resistant coatings are an effective means of reducing submarine noise and evading enemy detection, and have been extensively studied in recent years.

[0003] Traditional covering layers are often composed of cavity structures, which block or dissipate their own noise and external detection sound waves through internal structural damping and the role of local resonance cores. At the same time, the honeycomb multi-cell design inside the covering layer can also eliminate external impacts to a certain extent, thus protecting the submarine itself. Under the premise of the same cost, traditional impact-resistant covering layers have the disadvantages of insufficient bearing capacity, difficulty in material upgrading, cumbersome installation and maintenance process, and high cost.

[0004] The present invention innovatively adopts the Waterbomb Origami (WO) structure as a covering layer, providing a new idea for the impact resistance of submarines. Summary of the invention

[0005] The purpose of the present invention is to provide an impact-resistant covering layer adopting an origami structure, a design method and an application thereof. The covering layer is a stacked origami structure with a large amount of space inside, which can be used for structural folding and unfolding. When an external load acts on the surface of the covering layer, its energy will be quickly transferred to the WO structure to cause it to deform, thereby dissipating energy.

[0006] To achieve the above object, the present invention provides a design method of an impact-resistant cover layer using an origami structure, comprising the following steps:

[0007] S1. According to the angle changes of dihedral angles corresponding to the peak creases and valley creases in the folding process of the WO structure, a kinematic model of the WO covering layer and a potential energy change model of the WO covering layer are constructed;

[0008] S2, selecting the length l of the valley crease and the folding degree φ of the WO structure as design parameters, and designing an impact-resistant covering layer based on the WO structure;

[0009] Among them, the WO structure is prepared using shape memory materials, and the shape memory materials remain isotropic in the x, y, and z directions in the global coordinate system and have the same mechanical properties.

[0010] Preferably, the length l of the valley fold is in the range of 15 mm to 40 mm; and the folding degree φ of the WO structure is in the range of 75% to 85%.

[0011] Preferably, in step S1, a kinematic model of the WO cover layer is constructed as follows:

[0012]

[0013] γ m =arccos(2 cos 2 θ-1)-π

[0014]

[0015] Among them, γ represents the angle between the peak crease and the vertical axis; θ represents the angle between the valley crease and the vertical axis; γ m and γ v denote the dihedral angle of the peak fold and the dihedral angle of the valley fold respectively; c = arccos[cos 2 (θ)]; α represents the angle between the peak crease and the valley crease when fully flattened,

[0016] Preferably, in step S1, a potential energy change model of the WO covering layer is constructed, specifically as follows:

[0017] W external impact =W WO +W protected structure

[0018] Among them, W external impact Represents the energy of external impact; W WO The energy dissipated by the WO structure covering layer is the part where the present invention works; protected structure It is the impact energy that the protected structure ultimately bears.

[0019] Preferably, the one-dimensional constitutive model of the shape memory material is obtained by modifying the linear viscoelastic theory:

[0020]

[0021] ε s =Sε c

[0022] Among them, σ, ε and T represent stress, strain and temperature respectively; E, μ and λ represent elastic modulus, viscosity and delay time respectively; S is the proportionality coefficient; ε c is the creep strain; ε s is the irrecoverable strain; β is the thermal expansion coefficient.

[0023] Preferably, the three-dimensional constitutive model of the shape memory material is obtained through a one-dimensional constitutive model:

[0024]

[0025] Among them, C and ε lThey represent the thresholds of coupling coefficient and creep strain respectively; σ ij and ε ij are the tensor representations of stress and strain respectively; v represents Poisson’s ratio; Represents the average value of creep strain; ε l (T) is ε l ; Indicates the delay time; represents the average value of creep participation strain; δ ij The symbol is Kroneck delta function; t1 represents when the creep strain rate changes from positive to negative moment;

[0026] Viscosity coefficient Delay time Creep residual strain ε S and creep strain It is expressed as:

[0027]

[0028]

[0029]

[0030]

[0031] When satisfied hour, and are the equivalent values ​​of ε and σ respectively;

[0032] During the temperature change, the shape memory material will undergo a transition between the glass state and the rubber state, so its material properties will also change significantly. In order to describe the thermo-mechanical behavior of the shape memory material, the relationship between the material parameters and the temperature is established to describe the thermo-mechanical behavior of the shape memory material:

[0033]

[0034] Among them, μ h , μ l are high temperature and low temperature viscosity coefficients, T hl is the temperature difference between low temperature and high temperature within the glass transition temperature range; z represents the reversible strain under certain material parameters;

[0035] Then z is introduced into the material parameter equation related to temperature to obtain the parameter equation of the shape memory material:

[0036] E(T)=(1-z)E l +zE h

[0037] μ(T)=(1-z)μ l +zμ h

[0038] λ(T)=(1-z)λ l +zλ h

[0039] v(T)=(1-z)v l +zv h

[0040] Where v(T) represents the Poisson’s ratio that varies with time, v h and v l are Poisson's ratio at high and low temperatures, respectively; μ(T) represents the viscosity that changes with time, μ h and μ l are the viscosities at high and low temperatures, respectively; E(T) represents the elastic modulus that changes with time, E h and E l are the elastic modulus at high and low temperatures, respectively; λ(T) represents the delay time, λ h and λ l are the delay times at high and low temperatures, respectively.

[0041] The present invention also provides an impact-resistant covering layer designed by a design method of an impact-resistant covering layer using an origami structure, wherein the layer thickness of the WO structure is 2 mm to 5 mm, the bending deformation modulus is 1.5 GPa to 2.5 GPa, the folding degree φ can reach 30% to 90%, and 75% to 85% is selected as the design index for actual use.

[0042] The present invention also provides an application of an impact-resistant covering layer adopting an origami structure in a submarine protective structure.

[0043] Therefore, the present invention adopts the above-mentioned impact-resistant covering layer with origami structure and the design method and application, and its technical effects are as follows:

[0044] (1) Since the cover layer is a stacked origami-like structure with a large amount of space inside, it can be used for structural folding and unfolding. When the external load acts on the surface of the cover layer, its energy will be quickly transferred to the WO structure, causing it to deform and dissipate energy;

[0045] (2) The impedance index of air is much smaller than that of the covering layer structure and water body. Due to the mismatch of impedance index, the shock wave will be dissipated in large quantities inside the covering layer;

[0046] (3) Since the peak folds and valley folds in the WO configuration intersect at the corners, this periodic tortuous shape interferes with the propagation of stress waves in the structure. When the stress wave propagates in the cover layer, the positions of the sharp points and large angles will undergo drastic waveform changes, thereby extending the propagation path of the stress wave and consuming more energy, thereby absorbing the huge energy brought by the impact and alleviating the damage caused by the impact to the structure.

[0047] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A schematic diagram of the design process for the impact-resistant cover structure;

[0049] Figure 2 It is a three-dimensional schematic diagram and deformation process of the structure of the present invention;

[0050] Figure 3 It is a front view of the deformation process of the present invention;

[0051] Figure 4 This is a schematic diagram of the specific installation of the impact-resistant covering layer. DETAILED DESCRIPTION

[0052] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0053] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0054] Embodiment 1

[0055] The WO structure is a typical multistable structure. Since it has a large expandable ratio between the expanded state and the encapsulated state, it can be potentially used to cover surfaces of different forms.

[0056] like Figure 1 FIG. 1 is a schematic diagram of the design process of the impact-resistant cover layer structure of the present invention, which specifically includes the following steps:

[0057] S1. According to the angle changes of dihedral angles corresponding to the peak creases and valley creases in the folding process of the WO structure, a kinematic model of the WO covering layer and a potential energy change model of the WO covering layer are constructed;

[0058] The length l of the valley fold ranges from 15 mm to 40 mm; the folding degree φ of the WO structure ranges from 75% to 85%.

[0059] The kinematic model of the WO covering layer is constructed as follows:

[0060]

[0061] γ m =arccos(2cos 2 θ-1)-π

[0062]

[0063] Among them, γ represents the angle between the peak crease and the vertical axis; θ represents the angle between the valley crease and the vertical axis; γ m and γ v denote the dihedral angle of the peak fold and the dihedral angle of the valley fold respectively; c = arccos[cos 2 (θ)]; α represents the angle between the peak crease and the valley crease when fully flattened,

[0064] The potential energy change model of WO covering layer is constructed as follows:

[0065] W external impact =W WO +W protected structure

[0066] Among them, W external impact Represents the energy of external impact; W WO The energy dissipated by the WO structure covering layer is the part where the present invention works; protected structure It is the impact energy that the protected structure ultimately bears.

[0067] S2, selecting the length l of the valley crease and the folding degree φ of the WO structure as design parameters, and designing an impact-resistant covering layer based on the WO structure;

[0068] Among them, the WO structure is prepared using shape memory materials, and the shape memory materials remain isotropic in the x, y, and z directions in the global coordinate system and have the same mechanical properties.

[0069] The one-dimensional constitutive model of shape memory material is obtained by modifying the linear viscoelastic theory:

[0070]

[0071] ε s =Sε c

[0072] Among them, σ, ε and T represent stress, strain and temperature respectively; E, μ and λ represent elastic modulus, viscosity and delay time respectively; S is the proportionality coefficient; ε c is the creep strain; ε s is the irrecoverable strain; β is the thermal expansion coefficient.

[0073] The three-dimensional constitutive model of shape memory materials is obtained through the one-dimensional constitutive model:

[0074]

[0075] Among them, C and ε l They represent the thresholds of coupling coefficient and creep strain respectively; σ ij and ε ij are the tensor representations of stress and strain respectively; ν represents Poisson’s ratio; Represents the average value of creep strain; ε l (T) is ε l ; Indicates the delay time; represents the average value of creep participation strain; δ ij The symbol is Kroneck delta function; t1 represents when the creep strain rate changes from positive to negative moment;

[0076] Viscosity coefficient Delay time Creep residual strain ε S and creep strain It is expressed as:

[0077]

[0078]

[0079]

[0080]

[0081] When satisfied hour, and are the equivalent values ​​of ε and σ respectively;

[0082] During the temperature change, the shape memory material will undergo a transition between the glass state and the rubber state, so its material properties will also change significantly. In order to describe the thermo-mechanical behavior of the shape memory material, the relationship between the material parameters and the temperature is established to describe the thermo-mechanical behavior of the shape memory material:

[0083]

[0084] Among them, μ h , μ l are high temperature and low temperature viscosity coefficients, T hl is the temperature difference between low temperature and high temperature within the glass transition temperature range; z represents the reversible strain under certain material parameters;

[0085] Then z is introduced into the material parameter equation related to temperature to obtain the parameter equation of the shape memory material:

[0086] E(T)=(1-z)E l +zE h

[0087] μ(T)=(1-z)μ l +zμ h

[0088] λ(T)=(1-z)λ l +zλ h

[0089] ν(T)=(1-z)v l +zv h

[0090] Where v(T) represents the Poisson’s ratio that varies with time, ν h and ν l are Poisson's ratio at high and low temperatures, respectively; μ(T) represents the viscosity that changes with time, μ h and μ l are the viscosities at high and low temperatures, respectively; E(T) represents the elastic modulus that changes with time, E h and E l are the elastic modulus at high and low temperatures, respectively; λ(T) represents the delay time, λ h and λ l are the delay times at high and low temperatures, respectively.

[0091] Embodiment 2

[0092] The present invention also provides an impact-resistant covering layer with an origami structure. The WO covering layer sample is made of shape memory resin RGD8510 material. The layer thickness of the WO structure is 2mm-5mm, the bending deformation modulus is 1.5GPa-2.5GPa, and the folding degree φ can reach 30%-90%. 75%-85% is selected as the design indicator for actual use.

[0093] The present invention is prepared by using shape memory material. Due to the shape memory characteristics, the structure of the covering layer can be controlled by changing the temperature so that it is fixed to different shapes, and the static and dynamic responses change.

[0094] like Figure 2 and Figure 3 As shown in FIG. 1 , when the WO covering layer is subjected to an external impact load, the stress wave will propagate circumferentially along the outer surface of the submarine (protected structure). Due to the expandable characteristics of the WO structure itself, the energy of the impact load will be rapidly dissipated circumferentially.

[0095] like Figure 2 As shown in the figure, different configurations have different impact resistance characteristics. If a smaller Waterbomb unit parameter is used, the overall structure can have better stability and withstand higher hydrostatic pressure. If a larger Waterbomb unit parameter is used, a better impact resistance effect can be obtained, that is, a larger deformation can be produced to absorb energy.

[0096] Embodiment 3

[0097] like Figure 4 As shown, the present invention also provides an application of an impact-resistant covering layer using an origami structure in a submarine protective structure. The application method is to assemble the impact-resistant covering layer obtained in Example 2 with a submarine.

[0098] In addition to submarines, the impact-resistant covering layer of the present invention can also be assembled and used with other protected structures (such as surface ships, armored vehicles, high-speed racing cars, anti-collision guardrails, protective dams, etc.).

[0099] Therefore, the present invention adopts the above-mentioned impact-resistant covering layer, design method and application using an origami structure. The covering layer is a stacked origami structure with a large amount of space inside, which can be used for structural folding and unfolding. When the external load acts on the surface of the covering layer, its energy will be quickly transferred to the WO structure to cause it to deform, thereby dissipating energy.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for designing an impact-resistant covering layer using an origami structure, characterized in that: The following steps are involved: S1. Constructing a kinematic model of a WO covering layer and a potential energy change model of a WO covering layer according to the angle changes of the dihedral angles corresponding to the peak creases and the valley creases during the folding process of the WO structure; the WO structure is a Waterbomb Origami structure; S2. Select the length of the valley crease and the folding degree of WO structure φ As the design parameters, the impact-resistant covering layer based on WO structure was designed; Among them, the WO structure is prepared using shape memory material, and the shape memory material is in the global coordinate system. x , y , z The three directions remain isotropic and have the same mechanical properties; The kinematic model of the WO covering layer is constructed as follows: ； ； ； in, γ It represents the angle between the peak fold and the vertical axis; It represents the angle between the valley crease and the vertical axis; and They represent the dihedral angles of the peak fold and the valley fold, respectively; ; The angle between the peak crease and the valley crease when fully flattened is ; The potential energy change model of WO covering layer is constructed as follows: ； in, Represents the energy of external impact; The energy dissipated by the WO structure covering layer; It is the impact energy that the protected structure ultimately bears.

2. The design method of the impact-resistant covering layer using an origami structure according to claim 1, characterized in that: Length of valley crease The range is 15mm~40mm; the folding degree of WO structure φ The range is 75%~85%.

3. The design method of the impact-resistant covering layer using an origami structure according to claim 2, characterized in that: The one-dimensional constitutive model of shape memory material is obtained by modifying the linear viscoelastic theory: ； ； in, , and denote stress, strain and temperature respectively; E , and represent elastic modulus, viscosity and delay time, respectively; is the proportionality coefficient; is the creep strain; It is irreversible strain; Represents the coefficient of thermal expansion.

4. The method for designing an impact-resistant covering layer using an origami structure according to claim 3, characterized in that: The three-dimensional constitutive model of shape memory materials is obtained through the one-dimensional constitutive model: ； Among them, C and denote the thresholds of coupling coefficient and creep strain, respectively; and are the tensor representations of stress and strain, respectively; represents Poisson's ratio; represents the average value of creep strain; Right now ; Indicates the delay time; represents the average value of creep participation strain; The notation is the Kroneck delta function; It means that when the creep strain rate changes from positive to negative moment; Viscosity coefficient , Delay time , creep residual strain and creep strain It is expressed as: ； ； ； ； When satisfied , hour, and They are and The equivalent value of During the temperature change, the shape memory material will undergo a transition between the glass state and the rubber state. Therefore, the relationship between material parameters and temperature is established to describe the thermo-mechanical behavior of the shape memory material: ； in, , are high temperature and low temperature viscosity coefficients respectively; is the temperature difference between low and high temperatures within the glass transition temperature range; represents the reversible strain under certain material parameters; Then z Introduced into the material parameter equation related to temperature, the parameter equation of shape memory material is obtained: ； ； ； ； in, represents the time-varying Poisson's ratio, and are the Poisson's ratio at high and low temperatures, respectively; represents the viscosity over time, and are the viscosities at high and low temperatures respectively; represents the time-varying elastic modulus, and are the elastic modulus at high and low temperatures, respectively; Indicates the delay time. and are the delay times at high and low temperatures, respectively.

5. An impact-resistant covering layer designed according to the design method of an impact-resistant covering layer using an origami structure according to any one of claims 1 to 4, characterized in that: The layer thickness of the WO structure is 2mm~5mm, the bending deformation modulus is 1.5GPa~2.5GPa, and the folding degree is 75%~85%.

6. Use of the impact-resistant covering layer with origami structure according to claim 5 in a submarine protective structure.

Images