Design of Ti-W wave impedance gradient material and wave attenuation effect test method

Abstract

The invention relates to a method for designing a Ti-W wave impedance gradient material and testing a wave attenuation effect, and belongs to the field of metal-based composite materials. The wave impedance gradient material disclosed by the invention is a multi-layer type layered composite material composed of two elements of titanium Ti and tungsten W; based on the elastic wave impedance of the composite material, gradually decreasing the wave impedance value of the composite material layer by layer by adjusting the mass percentage of W in each layer, and further attenuating shock waves; by adjusting the relative mass percent of the low-impedance element Ti and the high-impedance element W, the wave impedance value of each layer and the interlayer wave impedance gradient difference of the gradient material can be flexibly adjusted in a large range conveniently; the used elements can be infinitely and mutually soluble, so that the situation that harmful hard and brittle phases are formed in the material preparation process to reduce the overall mechanical property of the material is avoided; according to the gradient composite material, Ti serves as a base body on the whole, the base body is continuous although wave impedance value differences exist between the layers, an interlayer heterogeneous interface does not exist, and the risk of interlayer dissociation damage generated when the gradient composite material is impacted is reduced.

Description

Technical Field

[0001] The invention relates to a design of a Ti-W wave impedance gradient material and a wave attenuation effect testing method, and belongs to the field of metal-based composite materials. Background Art

[0002] Wave impedance gradient materials are functional gradient materials constructed around differences in material stress wave impedance. When subjected to high-speed impacts, these materials can dissipate the energy of stress waves, effectively reducing the impact stress at the rear end of the impact direction and enhancing the material's resistance to impact damage. Patent application number 202211525144.X proposes a Ti-Al-PTFE energetic wave impedance gradient material for hypervelocity impact protection against space debris. Combining the two protection concepts of impact detonation and wave impedance gradient energy dissipation, it offers excellent protection against space debris. The Al / Mg wave impedance gradient material prepared by Zhang et al. exhibits a more significant fragmentation effect against high-speed impact projectiles. Fernando et al. prepared a Fe-Ti-Al wave impedance gradient target plate and verified the attenuation effect of the wave impedance gradient material on shock wave amplitude through experimental and numerical analysis. However, the methods for preparing wave impedance gradient materials in publicly reported technologies often involve joining several common material sheets together through gluing or welding. The wave impedance values ​​of each layer are fixed and cannot be changed, and the wave impedance gradient difference between layers cannot be controlled. Furthermore, when dissimilar metals are composited, significant interfaces exist. Diffusion of elements at these interfaces can form hard and brittle phases such as intermetallic compounds, weakening the bonding strength between the gradient composite layers and increasing the risk of interlayer dissociation and failure under high-speed impact. Furthermore, no mature technology has been reported to effectively measure and evaluate the stress wave attenuation efficiency of materials.

[0003] Therefore, developing a wave impedance gradient material with flexible control over the wave impedance values ​​of each layer and the wave impedance gradient difference between layers, without heterogeneous interfaces, to fully utilize the energy dissipation function of the layered composite material is of great significance to the development of high-performance protective materials. Furthermore, proposing a convenient, effective, and easy-to-use method for measuring wave attenuation efficiency is extremely valuable for the performance evaluation and promotion and application of wave impedance gradient materials. Summary of the Invention

[0004] The present invention aims to provide a design and testing method for a Ti-W wave impedance gradient material. This method can achieve flexible regulation of the wave impedance value between composite layers. The prepared wave impedance gradient material has a dense microstructure, no heterogeneous interfaces, and a significant wave attenuation effect. The proposed wave attenuation efficiency measurement method is simple and easy to use.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A design method for a Ti-W wave impedance gradient material. The wave impedance gradient material is a multilayer composite material composed of titanium (Ti) and tungsten (W). Based on the elastic wave impedance of the composite material, the wave impedance value of the composite material is gradually reduced layer by layer by adjusting the mass percentage of W in each layer, thereby achieving attenuation of shock waves. The specific implementation method is as follows:

[0007] When the elastic longitudinal wave is transmitted from the incident layer A to the transmission layer B, its transmission wave stress σ T and the incident wave stress σ I The ratio is:

[0008]

[0009] Where, ρ A and ρ B are the densities of the incident layer A and the transmission layer B, C A and C B are the stress wave velocities of the incident layer A and the transmitted layer B, respectively;

[0010] The total number of layers of the wave impedance gradient material is N, and the total attenuation efficiency is λ. If the wave attenuation efficiency of each layer in the wave impedance gradient material is set to a constant value, we can obtain:

[0011] (σ T / σ I ) N-1 =1-λ (2)

[0012] The ratio of the wave impedance of the incident layer A and the transmission layer B can be obtained by combining:

[0013]

[0014] Furthermore, in a gradient material with a total number of N layers, the wave impedance value of the nth layer (n = 1, 2, 3, ..., N) satisfies the following formula:

[0015]

[0016] Where the subscript 1 represents the first layer of the wave impedance gradient material. At the same time, according to the superposition principle of mechanical mixtures, the density ρ and elastic longitudinal wave velocity C of the multi-component alloy are:

[0017]

[0018] Where w i , ρ i and C i are the mass percentage, density and elastic longitudinal wave velocity of component i in the multi-component system respectively;

[0019] In the Ti-W binary system, let the mass fraction of W in the nth layer be x n, it can be concluded that the density and longitudinal wave velocity of the nth layer satisfy:

[0020]

[0021]

[0022] Where, ρ Ti and ρ W are the zero-pressure densities of pure Ti and pure W, respectively, C Ti and C W are the elastic longitudinal wave velocities of pure Ti and pure W respectively;

[0023] The first layer of the material is a pure Ti layer with the lowest wave impedance value. According to formulas (4), (7), (8), we can get:

[0024]

[0025] Further, according to formula (9), the mass percentage of W in the nth layer of the wave impedance gradient material is obtained as x n .

[0026] According to the mass percentage x of W in the nth layer n (n=1,2,3,…,N) Determine the mass ratio of tungsten to titanium used in each layer of powder; Add tungsten powder and titanium powder to dispersant liquid and perform ball milling to obtain a uniform slurry; Vacuum dry the slurry to obtain composite powder; According to x n Composite powders with different composition ratios are stacked layer by layer and loaded into a sheath mold; hot isostatic pressing and sintering are performed to obtain a Ti-W wave impedance gradient material with a continuous matrix and no macroscopic interface.

[0027] The ball milling mixing method is: Ti powder with a particle size of 10 to 90 μm and W powder with a particle size of 5 to 30 μm are mixed according to the designed x n Mechanical ball milling was performed to obtain Ti-W composite powders with different W contents required for different wave impedance layers. The powder mixing process was as follows: anhydrous ethanol was used as the ball milling medium, the mass ratio of grinding balls to total materials was (5-10):1; the ball milling speed was 150-250 r / min, and the ball milling time was 3-6 h.

[0028] The hot isostatic pressing method comprises: slowly injecting Ti-W composite powders with different W contents into a pure titanium sheath in the order of change of wave impedance (from small to large or from large to small); using a clean graphite indenter to compact the powder until the surface is flat for each injected layer, and ensuring that the thickness of each layer is the same; then, hot isostatic pressing is used to consolidate and form the gradient material; and the sintering process comprises: using a vacuum atmosphere, a sintering temperature of 1100-1300°C, a heating rate of 100°C / min, a sintering pressure of 100-150 MPa, and a heat preservation and pressure holding time of 2-3 hours.

[0029] The measurement system includes: Ti-W wave impedance gradient material to be measured, impact plate, high-speed launch device and three-channel Doppler probe photoelectric conversion measurement system;

[0030] The test method is as follows: a high-speed launcher is used to launch an impact plate at a certain speed coaxially and parallel to the outer surface of the highest wave impedance value layer in the stepped wave impedance gradient material target plate; a three-channel Doppler probe photoelectric conversion system is used to measure the particle velocity on the free surface of each step, and the shock wave stress σ is obtained based on the particle velocity, thereby determining the actual wave attenuation efficiency λ of the wave impedance gradient material. A .

[0031] The impact state parameters of the impact plate are known; the Ti-W wave impedance gradient material is in a step-like shape; and the material is arranged according to the size of the wave impedance value, with the first step being located in the highest layer of the wave impedance value.

[0032] Determine the actual wave attenuation efficiency λ of the wave impedance gradient material A The method is as follows:

[0033] The particle velocity on the free surface of each step is measured using a three-channel Doppler probe photoelectric conversion system The subscript j represents the detection probe j, and the following formula is used to convert The value is converted to shock wave stress σ j value:

[0034]

[0035] Where ρ0 is the density of the material at normal pressure, C0 and S are the impact state parameters of the material;

[0036] Using σ j The actual wave attenuation efficiency λ of the wave impedance gradient material is determined by the value A :

[0037]

[0038] Where σ1 and σ2 are the shock wave stress values ​​measured by detection probes 1 and 2 at different positions on the first step, respectively, and σ3 is the shock wave stress value measured by detection probe 3 on the second step.

[0039] Beneficial effects:

[0040] (1) By adjusting the relative mass percentages of the low-impedance element Ti and the high-impedance element W, the wave impedance values ​​of each layer of the gradient material and the wave impedance gradient difference between layers can be flexibly adjusted within a large range, and the material design is no longer restricted by the fixed wave impedance values ​​of common materials; the selected Ti and W elements are infinitely miscible, avoiding the formation of harmful hard and brittle phases during the material preparation process, which would reduce the overall mechanical properties of the material; the gradient composite material is based on Ti as a matrix. Although there are differences in wave impedance values ​​between the layers, the matrix is ​​continuous and there is no heterogeneous interface between the layers, which reduces the risk of interlayer dissociation and damage during impact.

[0041] (2) The present invention's material impedance design method, which uses elastic wave impedance to calculate the W content in each layer of a gradient material, is relatively simple and can be easily extended to other material systems besides Ti-W. This method, based on the fact that Ti-W system wave impedance gradient materials attenuate plastic waves (shock waves) more efficiently than elastic waves, considers the material's elastic wave impedance as a factor in the calculation. This reduces the amount of computation while providing sufficient design redundancy for wave attenuation efficiency, thus simplifying the material design process.

[0042] (3) The raw materials and preparation process are simple, with low energy consumption, strong stability and controllability, which is conducive to industrial application.

[0043] (3) The proposed wave attenuation efficiency measurement system and method can calculate the wave attenuation efficiency of the wave impedance gradient material by simply measuring the free surface particle velocity at different positions of the stepped target plate. It is easy to operate and has high test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a low-magnification optical metallographic microscope image of a cross section of the 65W / 55W / 43W / 26W / Ti wave impedance gradient material prepared in Example 1;

[0045] Figure 2 This is a low-magnification optical metallographic microscope image of a cross section of the 80W / 64W / 39W / Ti wave impedance gradient material prepared in Example 2;

[0046] Figure 3 Schematic diagram of the wave attenuation efficiency measurement system used in Example 2;

[0047] Figure 4 This is the impact stress-time relationship curve in the wave impedance gradient material measured under different impact pressure (velocity) conditions in Example 2. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] Example 1:

[0050] The total number of layers of Ti-W wave impedance gradient material is set to N = 5, the wave attenuation efficiency is set to λ = 20%, and the first layer is set to be a pure Ti layer. The mass percentage of W in the nth layer (n = 1, 2, 3, 4, 5) can be obtained as x n for:

[0051]

[0052] Among them, it can be found from the material manual: ρ Ti =4.527g / cm 3 , ρ W =19.235g / cm 3 , C Ti =6.16km / s, C W =5.22 km / s. Substituting the corresponding parameters into the above formula, we can obtain the mass percentage (wt.%) of W in each layer of the wave impedance gradient material as 0, 26%, 43%, 55% and 65% respectively.

[0053] Ti powder with an average particle size of 40 μm and W powder with an average particle size of 30 μm were weighed according to the above ratio and placed in separate ball mills, with a total of 100 g in each jar. 500 g of grinding balls were then placed in each jar (a ball-to-material ratio of 5:1). Anhydrous ethanol, the milling medium, was then injected until the material and the grinding balls were completely submerged. The jars were then sealed and low-energy ball milled at 200 rpm for 4 hours to produce a composite slurry. The resulting composite slurry was then placed in a vacuum drying oven and dried at 80°C for 12 hours. The dried powder was then filtered through a 60-mesh sieve to obtain a uniformly mixed composite powder.

[0054] Composite powders with different W contents were slowly injected into a pure titanium sheath with an inner diameter of Φ40 mm in the order of wave impedance change from small to large. A clean graphite indenter was used to compact the powder until the surface was flat each time a layer was injected, and the thickness of each layer was ensured to be the same. Subsequently, the gradient material was consolidated and formed by hot isostatic pressing to obtain a bulk Ti-W wave impedance gradient material. The sintering process parameters were: sintering temperature of 1200°C, heating rate of 100°C / min, sintering pressure of 130 MPa, and holding time of 2 h.

[0055] Example 2:

[0056] The total number of layers of the Ti-W wave impedance gradient material is set to N = 4, the elastic wave attenuation efficiency is set to λ = 30%, and the first layer is set to be a pure Ti layer. The mass percentage of W in the nth layer (n = 1, 2, 3, 4) is obtained as x n for:

[0057]

[0058] Among them, it can be found from the material manual: ρ Ti =4.527g / cm 3 , ρ W =19.235g / cm 3 , C Ti =6.16km / s, C W =5.22 km / s. Substituting the relevant parameters into the above formula, we can obtain the mass percentage (wt.%) of W in each layer of the wave impedance gradient material as 0, 39%, 64% and 80% respectively.

[0059] Ti powder with an average particle size of 40 μm and W powder with an average particle size of 30 μm were weighed according to the above ratio and placed in separate ball mills, with a total of 100 g in each jar. 500 g of grinding balls were then placed in each jar (a ball-to-material ratio of 5:1). Anhydrous ethanol, the milling medium, was then injected until the material and the grinding balls were completely submerged. The jars were then sealed and low-energy ball milled at 200 rpm for 4 hours to produce a composite slurry. The resulting composite slurry was then placed in a vacuum drying oven and dried at 80°C for 12 hours. The dried powder was then filtered through a 60-mesh sieve to obtain a uniformly mixed composite powder.

[0060] Composite powders with different W contents were slowly injected into a pure titanium sheath with an inner diameter of Φ40 mm in the order of wave impedance change from small to large. A clean graphite indenter was used to compact the powder until the surface was flat each time a layer was injected, and the thickness of each layer was ensured to be the same. Subsequently, the gradient material was consolidated and formed by hot isostatic pressing to obtain a bulk Ti-W wave impedance gradient material. The sintering process parameters were: sintering temperature of 1200°C, heating rate of 100°C / min, sintering pressure of 130 MPa, and holding time of 2 h.

[0061] The low-magnification optical metallographic microscope images of the cross-sections of the 65W / 55W / 43W / 26W / Ti wave impedance gradient material prepared in Example 1 and the 80W / 64W / 39W / Ti wave impedance gradient material prepared in Example 2 are shown in FIG. Figure 1 and Figure 2As shown in the figure, it can be seen that in the two Ti-W wave impedance gradient materials with different components, the W particles are evenly distributed in the Ti matrix, the structure is dense and free of holes, the interlayer boundaries are clear, but the Ti matrix is ​​continuous.

[0062] The prepared 80W / 64W / 39W / Ti wave impedance gradient material is processed into Figure 3 The stepped target plate shown in the figure has a first step located in the layer with the highest wave impedance value of 80wt.% W content, and detection probes 1 and 2 are arranged on the back of the first step. The second step is a pure Ti layer with the lowest wave impedance value, and detection probe 3 is arranged on the back of the second step. The impact plate is made of pure Ti. A high-speed launch device is used to launch the impact plate to coaxially and parallelly impact the outer surface of the layer with the highest wave impedance value in the stepped wave impedance gradient material target plate at a certain speed V; a three-channel Doppler probe photoelectric conversion system is used to measure the particle velocity on the free surface of the first and second steps of the stepped wave impedance gradient material target plate, and the following formula is used to convert it into The value is converted to shock wave stress σ j Value (subscript j represents detection probe j):

[0063]

[0064] Among them, ρ0 at the first step is 11.66g / cm 3 , C0=4.5km / s, S=1.18; ρ0=ρ at the second step Ti =4.527g / cm 3 , C0=5.01km / s, S=0.98. Figure 4 The figure shows the relationship between the shock wave stress σ obtained under different impact pressures (impact velocities) and time. When the preset impact pressure is 9 GPa (impact velocity is 473 m / s), the peak impact stresses measured at the first step are σ1 = 9.15 GPa and σ2 = 9.56 GPa, respectively, and the peak impact stress measured at the second step is σ3 = 5.03 GPa. It should be noted that the amplitude of the stress wave measured at this time is greater than the Hugoniot elastic limit of the elastic wave, that is, the measured parameter is actually the impact stress of the plastic wave (shock wave), then the actual shock wave attenuation efficiency λ of the wave impedance gradient material is A :

[0065]

[0066] Substitute relevant data to calculate λ A=46%. When the preset impact pressure is 20GPa (impact velocity is 954m / s), the peak impact stresses measured at the first step are σ1=19.45GPa and σ2=19.55GPa, and the peak impact stress measured at the second step is σ3=10.84GPa. The λ of the wave impedance gradient material is A =44%. Thus, it can be seen that under different impact pressure (velocity) conditions, the 80W / 64W / 39W / Ti wave impedance gradient material prepared in this embodiment can effectively attenuate shock wave stress, and the material's shock wave attenuation efficiency far exceeds the designed elastic wave attenuation efficiency (30%), providing sufficient design redundancy and meeting design expectations.

[0067] Comparative Example 1:

[0068] To illustrate the simplicity and efficiency of the proposed method for designing wave impedance gradient materials (using elastic wave parameters to calculate the W content in each layer of the gradient material), the case of performing related calculations using shock wave parameters is given here for comparison.

[0069] Due to the different amplitude shock wave (impact velocity) conditions, the shock wave velocity U S and material density are not constant, so the impact state equation needs to be used to calculate the wave attenuation efficiency of the material and the W content in each layer. When the subsequent wave propagation process is not considered, the transmitted wave stress σ can be simply considered to be T and the incident wave stress σ I That is, the wave intensity in substance A and substance B. Suppose the mass percentage of W element in the nth layer is x n , then applying the superposition principle, the impact Hugoniot parameters of the corresponding layers can be obtained as follows:

[0070]

[0071] S n =x n S W +(1-x n )S Ti (14)

[0072] For conventional metal materials, the shock wave velocity U S and particle velocity u P The following relationship exists:

[0073] U S =C0+S·u P (15)

[0074] Furthermore, according to the impedance matching principle, we can obtain:

[0075]

[0076] Simultaneously combining equations (12) to (17) and substituting the impact Hugoniot parameter of pure Ti, we can obtain 2～N and The number of independent equations in the 2N-1 equation group is greater than 2N-1, so the equation group can be solved theoretically. However, in actual calculation, because the mass percentage of W x n ρ n 、 and S n will have an impact, thereby changing the U of the corresponding material layer S 、u P and σ values, so solving the above N-dimensional equations is very complex. In contrast, using elastic wave parameters (all constant) for calculation is simpler and more practical. On the other hand, as can be seen from Example 2, the wave impedance gradient material has a greater attenuation efficiency for stress waves with amplitudes exceeding the elastic limit, i.e., shock waves, than elastic waves, which also demonstrates the reliability of using elastic wave parameters for related calculations and the design of wave impedance gradient materials.

[0077] The above specific description further illustrates the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A design method for a Ti-W wave impedance gradient material, characterized by: The wave impedance gradient material is a multi-layer composite material composed of two elements, titanium Ti and tungsten W. Based on the elastic wave impedance of the composite material, the wave impedance value of the composite material is gradually reduced layer by layer by adjusting the mass percentage of W in each layer, thereby achieving attenuation of shock waves.

2. A design method for a Ti-W wave impedance gradient material, characterized by: The specific implementation method is: When the elastic longitudinal wave is transmitted from the incident layer A to the transmission layer B, its transmission wave stress σ T and the incident wave stress σ I The ratio is: Where, ρ A and ρ B are the densities of the incident layer A and the transmission layer B, C A and C B are the stress wave velocities of the incident layer A and the transmitted layer B, respectively; The total number of layers of the wave impedance gradient material is N, and the total attenuation efficiency is λ. If the wave attenuation efficiency of each layer in the wave impedance gradient material is set to a constant value, we can obtain: (s T / s I ) N-1 =1-λ (2) The ratio of the wave impedance of the incident layer A and the transmission layer B is obtained as follows: In a gradient material with a total number of N layers, the wave impedance value of the n-th layer n = 1, 2, 3, ..., N materials satisfies the following formula: Where the subscript 1 represents the first layer of the wave impedance gradient material. At the same time, according to the superposition principle of mechanical mixtures, the density ρ and elastic longitudinal wave velocity C of the multi-component alloy are: Where w i , ρ i and C i are the mass percentage, density and elastic longitudinal wave velocity of component i in the multi-component system respectively; In the Ti-W binary system, let the mass fraction of W in the nth layer be x n , then the density and longitudinal wave velocity of the nth layer satisfy: Where, ρ Ti and ρ W are the zero-pressure densities of pure Ti and pure W, respectively, C Ti and C W are the elastic longitudinal wave velocities of pure Ti and pure W respectively; The first layer of the material is a pure Ti layer with the lowest wave impedance value. According to formulas (4), (7), (8), we can get: Further, according to formula (9), the mass percentage of W in the nth layer of the wave impedance gradient material is obtained as x n .

3. A method for preparing a composite material based on the result of the method according to claim 1 or 2, characterized in that: According to the mass percentage x of W in the nth layer n (n=1,2,3,…,N) Determine the mass ratio of tungsten to titanium used in each layer of powder; Add tungsten powder and titanium powder to dispersant liquid and perform ball milling to obtain a uniform slurry; Vacuum dry the slurry to obtain composite powder; According to x n Composite powders with different composition ratios are stacked layer by layer and loaded into a sheath mold; hot isostatic pressing and sintering are performed to obtain a Ti-W wave impedance gradient material with a continuous matrix and no macroscopic interface.

4. The method according to claim 3, wherein: The ball milling mixing method is: Ti powder with a particle size of 10 to 90 μm and W powder with a particle size of 5 to 30 μm are mixed according to the designed x n Mechanical ball milling was performed to obtain Ti-W composite powders with different W contents required for different wave impedance layers. The powder mixing process was as follows: anhydrous ethanol was used as the ball milling medium, the mass ratio of grinding balls to total materials was (5-10):1; the ball milling speed was 150-250 r / min, and the ball milling time was 3-6 h.

5. The method according to claim 3, wherein: The hot isostatic pressing method comprises the following steps: slowly injecting Ti-W composite powders with different W contents into a pure titanium sheath in the order of wave impedance change; using a clean graphite indenter to compact the powder until the surface is smooth after each layer is injected, and ensuring that the thickness of each layer is the same; and then consolidating the gradient material into a shape using hot isostatic pressing; the sintering process comprises the following steps: using a vacuum atmosphere, a sintering temperature of 1100-1300°C, a heating rate of 100°C / min, a sintering pressure of 100-150 MPa, and a heat and pressure holding time of 2-3 hours.

6. A method for testing the wave attenuation effect of a Ti-W wave impedance gradient material, characterized by: The wave attenuation effect of the material was tested using a measurement system. The measurement system includes: a Ti-W wave impedance gradient material to be tested, an impact plate, a high-speed launcher, and a three-channel Doppler probe photoelectric conversion measurement system. The test method is as follows: the high-speed launcher launches the impact plate at a certain speed coaxially and parallel to the outer surface of the highest wave impedance value layer in the stepped wave impedance gradient material target plate; the three-channel Doppler probe photoelectric conversion system measures the particle velocity on the free surface of each step, and the shock wave stress σ is obtained based on the particle velocity, thereby determining the actual wave attenuation efficiency λ of the wave impedance gradient material. A .

7. The method according to claim 6, wherein: The impact state parameters of the impact plate are known; the Ti-W wave impedance gradient material is in a step-like shape; and the material is arranged according to the size of the wave impedance value, with the first step being located in the highest layer of the wave impedance value.

8. The method according to claim 6, wherein: Determine the actual wave attenuation efficiency λ of the wave impedance gradient material A The method is as follows: The particle velocity on the free surface of the detection probe j is measured using a three-channel Doppler probe photoelectric conversion system. And through the following formula The value is converted to shock wave stress σ j value: Where, To detect the density of the material at normal pressure at probe j, With S j is the impact state parameter of the material at the detection probe j; Using σ j The actual wave attenuation efficiency λ of the wave impedance gradient material is determined by the value A : Where σ1 and σ2 are the shock wave stress values ​​measured by detection probes 1 and 2 at different positions on the first step, respectively, and σ3 is the shock wave stress value measured by detection probe 3 on the second step.

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