Method for evaluating protection performance of steel-PUF (Physical Unclonable Function) protection device based on model crushing performance

Abstract

The invention discloses a method for evaluating the protection performance of a steel-PUF protection device based on model crushing performance, and belongs to the technical field of bridge protection device performance detection, and the method comprises the steps: carrying out an impact test to obtain a steel-PUF protection model and an energy-deformation curve corresponding to the steel protection model; further establishing an energy-deformation curve of the full-size steel-PUF protection device by combining a similarity ratio coefficient; based on the energy-deformation curve and the similarity ratio coefficient of the full-size steel-PUF protection device, obtaining crushing performance evaluation indexes of the full-size steel-PUF protection device, including effective crushing force MCF and equivalent crushing force EMCF, and based on the evaluation indexes, performing ship collision protection performance evaluation on the full-size steel-PUF protection device. Or the installation suitability of the full-size steel-PUF protection device and the bridge is judged. According to the method provided by the invention, whether the designed steel-PUF protection device considers multiple factors such as the bridge pier size, the fortification requirement and the engineering economy or not can be quickly and accurately judged, and the evaluation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of performance detection of bridge protection devices, and particularly to an evaluation method for the protection performance of steel-PUF protection devices based on the crushing performance of models. Background Art

[0002] Bridge protection devices are used to absorb impact energy, reduce impact force, and protect the safety of bridge structures when ships collide with bridges. Due to the large scale of the protection devices, if the real ship collision test is directly used to test their protection performance, the operation difficulty and cost are relatively high. Therefore, although the FEA model can be used for simulation analysis to avoid preparing real large-scale physical models and is not restricted by actual test conditions, the performance data of the protection devices under different conditions can be obtained in a relatively simple way.

[0003] However, the steel-PUF protection device is developed based on the steel protection device, and PUF foam is filled inside the traditional steel protection device. Since the PUF foam is completely filled inside the steel shell, the PUF foam can play a supporting role during impact. However, the constitutive relationship between the steel and PUF materials under impact conditions is extremely complex, and it is difficult to accurately evaluate their performance by means of simulation analysis. At the same time, the simulation analysis process requires a large amount of computing resources and computing time, with a relatively high computing cost and low efficiency. Summary of the Invention

[0004] The present invention aims to overcome the problems of low simulation analysis efficiency and low accuracy in the protection structure and ship collision process in the prior art, and proposes an evaluation method for the protection performance of steel-PUF protection devices based on the crushing performance of models.

[0005] To achieve the above object, the technical solution of the present invention is: an evaluation method for the protection performance of steel-PUF protection devices based on the crushing performance of models, including,

[0006] Step S1, performing impact tests on the steel-PUF protection model and the corresponding steel model, and respectively obtaining the energy-deformation curves of the steel-PUF protection model and the corresponding steel model;

[0007] Step S2, establishing the energy-deformation curve of the full-scale steel-PUF protection device according to the similarity ratio coefficient between the steel-PUF protection model and the full-scale steel-PUF protection device, and the energy-deformation curves of the steel-PUF protection model and the steel model;

[0008] Step S3: Based on the steel-PUF protection model and the energy-deformation curve of the full-scale steel-PUF protection device, calculate the crushing performance evaluation index of the full-scale steel-PUF protection device in combination with the similarity ratio coefficient, so as to evaluate the ship collision protection performance of the full-scale steel-PUF protection device or judge the installation adaptability of the full-scale steel-PUF protection device and the bridge.

[0009] In one embodiment, in step S3, the evaluation index includes the effective crushing force MCF of the full-scale steel-PUF protection device β , and the expression is as follows:

[0010] MCF β =(E s +E p ) / (ED·β) (3-2)

[0011] ED is the effective deformation of the steel-PUF protection model, E s is the effective energy absorption of the full-scale steel device, E p is the effective energy absorption of the full-scale PUF material device, and β is the length similarity ratio coefficient between the full-scale steel-PUF protection device and the steel-PUF protection model.

[0012] In one embodiment, in step S3, the following relationship is satisfied between the effective crushing force and the axial length of the full-scale steel-PUF protection device:

[0013] L=a + b·MCF β ―c·MCF β 2 (3-6)

[0014] Wherein, L is the axial length of the full-scale steel-PUF protection device, MCF β is the effective crushing force of the full-scale steel-PUF protection device, and a, b, and c are constants under different ship types;

[0015] The axial length L is used to judge whether the axial length of the steel-PUF protection device under full scale matches the pier size.

[0016] In one embodiment, in step S3, the evaluation index further includes the equivalent crushing force EMCF of the full-scale steel-PUF protection device, and the expression is as follows:

[0017] EMCF = MCF β ·L / l (3-4)

[0018] Wherein, EMCF is the model equivalent crushing force of the full-scale steel-PUF protection device, MCF βis the effective crushing force of the full-scale steel-PUF protection device; L is the axial length of the full-scale steel-PUF protection device, and l is the axial length of the steel-PUF protection model.

[0019] In one embodiment, in step S3, the equivalent crushing force EMCF of the full-scale steel-PUF protection device and the peak value F of the ship collision impact force max satisfy the following relationship:

[0020] F max = A + B·EMCF (3-5)

[0021] where A and B are constants under different ship types.

[0022] In one embodiment, in step S2, the expressions for the effective absorption energy of the full-scale steel device and the effective absorption energy of the full-scale PUF material device are as follows:

[0023] E s = e s ·β PE (2-7)

[0024] E p = e p ·β SE (2-8)

[0025] where e S is the effective absorption energy of the steel model, β PE is the energy similarity ratio coefficient between the full-scale steel device and the steel model, e P is the effective absorption energy of the PUF material model, and β SE is the energy similarity ratio coefficient between the full-scale PUF material device and the PUF material model.

[0026] In one embodiment, in step S2, the similarity ratio coefficients β pE and β SE are obtained based on the similarity ratio criterion, and the expressions are as follows:

[0027] β PE = β 3+2j / (j―2) (2-4)

[0028] β SE = β 3+2q / (q―2) (2-5)

[0029] where β is the length similarity ratio coefficient between the steel-PUF protection device and the steel-PUF protection model, j is the material constant of the PUF material model, and q is the material constant of the steel model.

[0030] And the effective absorption energy e of the PUF material model p satisfies:

[0031] e p = e a - e s (2 - 6)

[0032] e s is the effective absorption energy of the steel model, e P is the effective absorption energy of the PUF material model, and e a is the effective absorption energy of the steel-PUF protection model.

[0033] In one embodiment, in step S2, a quasi-static compression test is performed on the PUF material model to obtain the stress-strain curve of the PUF material model, and fitting is performed according to the test data to obtain the relationship function between the strain rate and stress of the PUF material model, and the expression is as follows:

[0034]

[0035] The material constant j of the PUF material model is obtained according to formula 2-2, where σ d and σ0 are the dynamic stress and static stress under impact of the PUF material model respectively, ε, and are the strain, strain rate under static pressure and true strain rate of the PUF material model respectively, a and b are constants, and j = a + bε.

[0036] In one embodiment, in step S2, according to the Norton-Hoff equation, the relationship between the dynamic yield stress σ d of the steel model and the quasi-static yield stress σ0 is as follows:

[0037]

[0038] The material constant q of the steel model is obtained according to Equation 2-1, where, is the strain rate of the steel model, is the true strain rate of the steel model under impact.

[0039] In one embodiment, in step S1, the steel model and the steel-PUF model are consistent in the steel structure part; a crushing curve is also obtained in the impact test, the deformation amounts in the yield stage, damage stage and failure stage in the crushing curve are effective deformation amounts, and the impact forces in these three stages are obtained from the crushing curve. The effective absorption energy is obtained after being calculated from the impact force and the effective deformation amount, and the expression of the effective absorption energy is as follows:

[0040]

[0041] Among them, F(x) is the impact force, δ is the effective deformation amount, and EA is the effective absorption energy.

[0042] In summary, the present invention provides an evaluation method for the protection performance of a steel-PUF protection device based on the model crushing performance. The anti-collision performance evaluation indexes, including the equivalent crushing force EMCF and the effective crushing MCF, are obtained through the analysis of the results of the impact test, which are used to quickly and accurately judge whether the designed steel-PUF protection device takes into account multiple factors such as pier size, fortification requirements, and engineering economy, improving the evaluation efficiency.

[0043] To make the above features and advantages of the invention more obvious and understandable, specific embodiments are hereinafter given and described in detail in conjunction with the accompanying drawings. Description of the Drawings

[0044] Figure 1 It is a flowchart in the present invention.

[0045] Figure 2 It is a schematic diagram of the steel-PUF protection model in the present invention.

[0046] Figure 3 It is a comparison chart of the crushing curves of the steel model and the steel-PUF protection model in the present invention.

[0047] Figure 4 It is a comparison chart of the energy-deformation curves of the steel model and the steel-PUF protection model in the present invention. Detailed Embodiments

[0048] To make the objectives and technical solutions of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0049] Aiming at the problems of low simulation analysis efficiency and low accuracy of the protection structure and the ship collision process, the present invention proposes an evaluation method for the protection performance of a steel-PUF protection device based on the model crushing performance. Figure 1 It is a flowchart in the present invention. As Figure 1 shown, the present invention includes the following steps:

[0050] Step S1, conduct impact tests on the steel-PUF protection model and the corresponding steel model, and respectively obtain the energy-deformation curves of the steel-PUF protection model and the corresponding steel model;

[0051] Step S2, based on the similarity ratio coefficient between the steel-PUF protection model and the full-scale steel-PUF protection device, and the energy-deformation curves of the steel-PUF protection model and the steel model, establish the energy-deformation curve of the full-scale steel-PUF protection device;

[0052] Step S3, based on the energy-deformation curves of the steel-PUF protection model and the full-scale steel-PUF protection device, and in combination with the similarity ratio coefficient, calculate the crushing performance evaluation index of the full-scale steel-PUF protection device to evaluate the ship collision protection performance of the full-scale steel-PUF protection device, or judge the installation adaptability of the full-scale steel-PUF protection device and the bridge.

[0053] In step S1, the steel-PUF protection model is jointly composed of a steel model and a PUF material model (see Figure 2 , where Steel is the steel model and PUF is the PUF material model). The steel model is completely consistent with the steel-PUF model in the steel structure part. The difference is that the steel-PUF model is filled with PUF foam inside the steel model, which further improves the protection performance. Due to the low strength and uneven deformation of the PUF material model, it is difficult to directly measure the crushing curve of the PUF material model. Therefore, only the impact tests are carried out on the steel-PUF protection model and the steel model. During the impact test, ships with 1000 DWT, 2000 DWT, and 3000 DWT are used to impact the model steel-PUF protection model and the steel model respectively at the same impact speed to obtain the crushing curves (see Figure 3 , where S-1 is the crushing curve of the steel model and P-1 is the crushing curve of the model steel-PUF protection model) and energy-deformation curves (see Figure 4, where S-1 represents the steel model, P-1 represents the model steel-PUF protection model, P-1(steel) represents the steel model part in the model steel-PUF protection model, and P-1(foam) represents the PUF material model structure part in the model steel-PUF protection model). Among them, the crushing curve will include a yield stage, a damage stage, a failure stage, and a crushed stage. According to the force and deformation characteristics of the impacted structure, the deformation amounts in the yield stage, the damage stage, and the failure stage in the crushing curve are defined as the effective deformation amount, and the impact forces in these three stages are obtained from the crushing curve. Define the absorbed energy in the crushing curve as the effective absorbed energy, and the effective absorbed energy is obtained after being calculated from the impact force and the effective deformation amount. The expression of the effective absorbed energy is as follows:

[0054]

[0055] Among them, P(x) is the impact force, δ is the effective deformation amount, that is, the total deformation amount in the yield stage, the damage stage, and the failure stage, and EA is the effective absorbed energy.

[0056] The effective deformation amount is an important index to measure the working range of the structure. The larger the effective deformation amount, the larger the space for the structure to effectively absorb energy. The size of the effective absorbed energy is directly related to the buffering effect of the structure and is an important index to measure the energy absorption efficiency of the structure under impact load.

[0057] The energy-deformation curve is composed of the effective deformation amount and the effective absorbed energy.

[0058] In step S2, according to the Norton-Hoff equation, the dynamic yield stress σ of the steel model d and the relationship between the quasi-static yield stress σ0 are as follows:

[0059]

[0060] According to formula 2-1, the material constant q of the steel model can be obtained, where is the strain rate of the steel model, is the true strain rate of the steel model under impact.

[0061] At the same time, a quasi-static compression test is carried out on the PUF material model to obtain the stress-strain curve of the PUF material model, and fitting is carried out according to the test data to obtain the relationship function between the strain rate and the stress of the PUF material model within 10 -3 -10 2 s -1 The expression is as follows:

[0062]

[0063] The material constant j of the PUF material model can be obtained according to Equation 2-2, where σ d and σ0 are the dynamic stress under impact and the stress under static pressure of the PUF material model respectively, ε, and are the strain, the strain rate under static pressure and the true strain rate of the PUF material model respectively, a and b are constants, and j = a + bε.

[0064] According to the VSG similarity ratio criterion, the similarity ratio coefficient of the energy of the steel model and the PUF material model can be obtained. Taking the PUF material model as an example, the derivation process is as follows:

[0065]

[0067] where Π 7m and Π 7p are dimensionless numbers, β E is the similarity ratio coefficient of energy, β G is the similarity ratio coefficient of material stiffness, β V0 is the similarity ratio coefficient of volume, and β is the similarity ratio coefficient of the axial length between the full-scale steel-PUF protection device and the steel-PUF protection model.

[0068] According to the above derivation, the energy similarity ratio coefficient β pE of the PUF material model can be obtained, and the expression is as follows:

[0069] β PE = β 3+2j / (j―2) (2-4) Similarly, the energy similarity ratio coefficient β SE of the steel model can be obtained, and the expression is as follows:

[0070] β SE = β 3+2q / (q―2) (2-5)

[0071] Furthermore, by combining Equation 1-1 and the crushing curve, the effective absorption energy e s of the steel model and the total effective absorption energy e a of the steel-PUF protection model under the scaled-down size can be calculated. Since the total effective absorption energy of the steel-PUF protection model is the linear superposition of the effective absorption energies of the steel model and the PUF material model, the effective absorption energy e p of the PUF material model can be obtained from the following relationship:

[0072] ep = e a - e s (2 - 6)

[0073] In addition, the expressions for the effective absorption energy of the full - scale steel device and the effective absorption energy of the full - scale PUF material device are as follows:

[0074] E s = e s ·β PE (2 - 7)

[0075] E p = e p ·β SE (2 - 8)

[0076] Wherein, e S is the effective absorption energy of the steel model, β PE is the energy similarity ratio coefficient between the full - scale steel device and the steel model, e P is the effective absorption energy of the PUF material model, β SE is the energy similarity ratio coefficient between the full - scale PUF material device and the PUF material model.

[0077] Combining the above formulas 2 - 4, 2 - 5 and 2 - 7, 2 - 8, the effective absorption energy of the full - scale steel - PUF protection device can be obtained as follows:

[0078] E a = E S + E P = e S ·β 3+2q(q―2) + e P ·β 3+2qj(j―2) (2 - 9)

[0079] Wherein, E S is the effective absorption energy of the full - scale steel device, E P is the effective absorption energy of the full - scale PUF material device, E a is the effective absorption energy of the full - scale steel - PUF protection device, e S is the effective absorption energy of the steel model, e P is the effective absorption energy of the PUF material model, j is the material constant of the PUF material model, and q is the material constant of the steel model.

[0080] In step S3, the effective crushing force MCF is defined as the average value of the impact force of the structure in the three stages of yield, damage, and failure, which is used to describe the average impact force level of the structure within the effective absorption energy range. The expression is as follows:

[0081] MCF = EA / δ (3-1)

[0082] Combining Equation 3-1 and Equation 2-9, the effective crushing force NCF of the full-scale steel-PUF protection device can be obtained as follows: β , as follows:

[0083] NCF β = E a / (β·ED) = (E s + E p ) / (ED·β) (3-2)

[0084] where ED is the effective deformation of the steel-PUF protection model, and β is the length similarity ratio coefficient of the steel-PUF protection model.

[0085] In addition, due to the different axial lengths of the steel-PUF protection model and considering the deformation characteristics of the steel-PUF protection model, the equivalent crushing force EMCF of the full-scale steel-PUF protection device proposed in combination with Equation 3-2 is as follows:

[0086] MCF β = (e s ·β 3+2q(q-2) + e p ·β 3+2j(j-2) ) / (ED·β) (3-3)

[0087] EMCF = MCF β ·L / l (3-4)

[0088] where MCF β is the effective crushing force of the full-scale steel-PUF protection device, L is the axial length of the full-scale steel-PUF protection device, and l is the axial length of the steel-PUF protection model.

[0089] The equivalent crushing force EMCF will be used to preliminarily judge the performance of the full-scale steel-PUF protection device under different axial lengths. The reasons are as follows: Set multiple groups of steel-PUF protection models with different shapes and sizes. Under the condition that the effective deformation is the same or similar, the axial length corresponding to the steel-PUF protection model with the most effective absorbed energy is the optimal axial length. According to the similarity ratio coefficient, the equivalent crushing force EMCF of the full-scale steel-PUF protection device at the optimal axial length can be obtained, and it is respectively fitted and analyzed with the peak value F max of the ship collision impact force obtained in the impact test, and the fitting formula is as follows:

[0090] F max = A + B·EMCF (3-5)

[0091] Among them, A and B are constants under different ship types. When the ship type is 1000 DWT, A is 3.7 and B is 0.997; when the ship type is 2000 DWT, A is 5.2 and B is 1.2; when the ship type is 3000 DWT, A is 7.9 and B is 1.35.

[0092] Through fitting analysis, it can be known that the equivalent crushing force EMCF and the peak impact force F max are positively correlated, that is, the greater the equivalent crushing force EMCF, the corresponding peak impact force F max is also higher. Therefore, the equivalent crushing force EMCF can be used to describe the anti-collision performance of the full-scale steel-PUF protection device.

[0093] Taking the effective crushing force corresponding to the equivalent crushing force EMCF and the axial length of the full-scale steel-PUF protection device for fitting, the results show that there is a quadratic function relationship between the effective crushing and the axial length, as shown below:

[0094] L = a + b·MCF β ―c·MCF β 2 (3-6)

[0095] where L is the axial length of the full-scale steel-PUF protection device, and MCF β is the effective crushing force of the full-scale steel-PUF protection device, and a, b, and c are constants under different ship types. When the ship type is 1000 DWT, a is 5.7, b is 6.6, and c is 5.9.

[0096] In practical engineering applications, the full-scale steel-PUF protection device needs to surround the pier. Therefore, the length of the steel-PUF protection device needs to match the lateral width of the pier. Combining the energy-deformation curve of the full-scale steel-PUF protection device and Equation 3-6 can quickly determine whether the pre-designed full-scale steel-PUF protection device is suitable for the target pier, improving the design efficiency. At the same time, the increase in the effective crushing force can bring about a reduction in the axial length of the full-scale steel-PUF protection device. Therefore, the effective crushing force can be fixed at the lowest value in the industry standard, and the shortest required axial length of the full-scale steel-PUF protection device can be calculated, which helps to improve economy and can determine the most economical axial length under the condition that the protection performance meets the requirements.

[0097] In summary, the present invention provides an evaluation method for the protection performance of a steel-PUF protection device based on the model crushing performance. The anti-collision performance evaluation indexes are obtained through the analysis of the results of the impact test, including the equivalent crushing force EMCF and the effective crushing MCF, which are used to quickly and accurately determine whether the designed steel-PUF protection device takes into account multiple factors such as pier size, fortification requirements, and engineering economy, thereby improving the evaluation efficiency.

[0098] Although the present invention has been disclosed as above by way of examples, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field to which the present invention pertains may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to that defined by the appended patent application scope.

Claims

1. An evaluation method for the protective performance of a steel-PUF protection device based on the model crushing performance, characterized in that Including, Step S1: Conduct impact tests on the steel-PUF protection model and the corresponding steel model, and respectively obtain the energy-deformation curves of the steel-PUF protection model and the corresponding steel model; Step S2: Based on the similarity ratio coefficient between the steel-PUF protection model and the full-scale steel-PUF protection device, and the energy-deformation curves of the steel-PUF protection model and the steel model, establish the energy-deformation curve of the full-scale steel-PUF protection device; Step S3: Based on the energy-deformation curves of the steel-PUF protection model and the full-scale steel-PUF protection device, and in combination with the similarity ratio coefficient, calculate the crushing performance evaluation index of the full-scale steel-PUF protection device to evaluate the ship collision protection performance of the full-scale steel-PUF protection device, or judge the installation adaptability of the full-scale steel-PUF protection device and the bridge.

2. The evaluation method for the protection performance of the steel-PUF protection device based on the model crushing performance according to claim 1, characterized in that, In step S3, the evaluation index includes the effective crushing force MCF of the full-size steel-PUF protection device β , and the expression is as follows: MCF β = (E s + E p ) / (ED·β) (3-2) ED is the effective deformation amount of the steel-PUF protection model, E s is the effective absorption energy of the full-size steel device, E p is the effective absorption energy of the full-size PUF material device, and β is the length similarity ratio coefficient between the full-size steel-PUF protection device and the steel-PUF protection model.

3. The method for evaluating the protection performance of the steel-PUF protection device based on the model crushing performance according to claim 2, wherein, In step S3, the following relationship is satisfied between the effective crushing force and the axial length of the full-scale steel-PUF protection device: L = a + b·MCF β ―c·MCF β 2 (3 - 6) where L is the axial length of the full-scale steel-PUF protection device, MCF β is the effective crushing force of the full-scale steel-PUF protection device, and a, b, and c are constants for different ship types; The axial length L is used to judge whether the axial length of the steel-PUF protection device at full scale matches the pier size.

4. The method for evaluating the protection performance of the steel-PUF protection device based on the model crushing performance according to claim 1, characterized in that In step S3, the evaluation index also includes the equivalent crushing force EMCF of the full-scale steel-PUF protection device, and the expression is as follows: EMCF = MCF β ·L / l (3-4) Among them, EMCF is the model equivalent crushing force of the full-scale steel-PUF protection device, and MCF β is the effective crushing force of the full-scale steel-PUF protection device; L is the axial length of the full-scale steel-PUF protection device, and l is the axial length of the steel-PUF protection model.

5. The method for evaluating the protection performance of the steel-PUF protection device based on the model crushing performance according to claim 4, wherein In step S3, the equivalent crushing force EMCF of the full-size steel-PUF protection device and the peak value F of the ship collision impact force max satisfy the following relationship: F max = A + B·EMCF (3-5) where A and B are constants for different ship types.

6. The method for evaluating the protection performance of the steel-PUF protection device based on the model crushing performance according to claim 2, wherein In step S2, the expressions for the effective absorbed energy of the full-scale steel device and the effective absorbed energy of the full-scale PUF material device are as follows: E s = e s ·β PE (2 - 7) E p = e p ·β SE (2 - 8) Among them, e S is the effective absorption energy of the steel model, and β PE is the energy similarity ratio coefficient between the full-scale steel device and the steel model, and e P is the effective absorption energy of the PUF material model, and β SE is the energy similarity ratio coefficient between the full-scale PUF material device and the PUF material model.

7. The method for evaluating the protection performance of the steel-PUF protection device based on the model crushing performance according to claim 6, wherein, In step S2, the similarity ratio coefficient β is obtained based on the similarity ratio criterion pE and β SE , and the expression is as follows: β PE ＝β 3+2j / (j―2) (2-4) β SE ＝β 3+2q / (q―2) (2-5) where β is the length similarity ratio coefficient between the steel-PUF protection device and the steel-PUF protection model, j is the material constant of the PUF material model, and q is the material constant of the steel model. and the effective absorption energy e of the PUF material model p satisfies: e p = e a -e s (2 - 6) e s is the effective absorption energy of the steel model, e P is the effective absorption energy of the PUF material model, e a is the effective absorption energy of the steel-PUF protection model.

8. The evaluation method for the protection performance of the steel-PUF protection device based on the model crushing performance according to claim 7, characterized in that In step S2, conduct a quasi-static compression test on the PUF material model to obtain the stress-strain curve of the PUF material model, and perform fitting based on the test data to obtain the relationship function between the strain rate and stress of the PUF material model, and the expression is as follows: Obtain the material constant j of the PUF material model according to Equation 2-2, where σ d and σ0 are the dynamic stress under impact and the stress under static pressure of the PUF material model, ε, and are the strain, the strain rate under static pressure and the true strain rate of the PUF material model, a and b are constants, and j = a + bε.

9. The method for evaluating the protection performance of the steel-PUF protection device based on the model crushing performance according to claim 7, characterized in that, In step S2, according to the Norton-Hoff equation, the relationship between the dynamic yield stress σ d of the steel model and the quasi-static yield stress σ0 is as follows: The material constant q of the steel model is obtained according to Equation 2-1, where is the strain rate of the steel model, is the true strain rate of the steel model under impact.

10. The evaluation method for the protection performance of the steel-PUF protection device based on the model crushing performance according to claim 1, characterized in that, In step S1, the steel model and the steel-PUF model are consistent in the steel structure part; a crushing curve is also obtained in the impact test. The deformation amounts in the yield stage, the damage stage, and the failure stage in the crushing curve are effective deformation amounts, and the impact forces in these three stages are obtained from the crushing curve. The effective absorbed energy is obtained after calculation from the impact force and the effective deformation amount, and the expression for the effective absorbed energy is as follows: where F(x) is the impact force, δ is the effective deformation amount, and EA is the effective absorbed energy.

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