Steel plate energy dissipation deformation measurement method, rockfall collision avoidance device design method, and application

Abstract

The application discloses a steel plate energy consumption deformation measurement method, a rockfall anti-collision device design method and application. In view of the defect that the prior art does not solve the problem of mathematical quantification of key parameters in the design of an anti-collision body, the application provides a steel plate energy consumption deformation measurement method for measuring the compression strain of a steel plate in a deformation process under the impact of a spherical body, the radius and volume of a steel plate deformation zone; a deformation energy consumption measurement method of a steel plate under the impact of a spherical body; an anti-collision body impact energy consumption measurement method for measuring the energy consumption performance of an anti-collision body with a composite sandwich structure; and application of the measurement methods in the calculation and evaluation of the anti-impact performance of a steel plate or the energy consumption performance of an anti-collision body. The application provides a rockfall anti-collision device design method for calculating design parameters of an energy consumption component according to energy relations. The application fills the technical gap of mathematical quantification of a steel plate energy consumption deformation process, improves the scientific nature of an energy consumption effect calculation scheme of a composite sandwich structure, and reduces design waste.

Description

TECHNICAL FIELD

[0001] The present application relates to material impact deformation measurement and anti-collision device design, in particular to a kind of energy dissipation deformation and anti-collision device design with steel plate as the impact surface, belong to the field of motion process measurement technology, engineering protection design technology, geological disaster prevention technology. BACKGROUND

[0002] Anti-collision safety design is an important part of the design of some specific buildings / structures including bridge piers. In engineering practice, high-absorptive materials such as aluminum foam and polyurethane, which have good energy dissipation and buffering performance, are processed into energy dissipation cores, and then covered with dense metal plates to form a "sandwich" type composite sandwich structure. The dense metal plate (usually steel plate) as the impact surface can effectively overcome the strength deficiency of high-absorptive materials due to their large pore volume and low density. This type of composite sandwich material has the advantages of light weight, high specific strength, outstanding energy absorption performance, convenient processing, and economical cost, and is widely used in the anti-collision part of the aforementioned specific buildings / structures and the design of anti-collision devices.

[0003] The existing technologies "Application of Aluminum Foam Protection Device in Bridge Pier Anti-collision" (Xu Dongfeng, Chongqing University of Technology, 2006), "Numerical Simulation of Vehicle-bridge Collision with New Composite Anti-collision Device" (Zhang Jianqiang et al., Highway, 2011, Vol. 31, No. 6), "Research on Polyurethane Sandwich Plate Bridge Pier Protection Device" (Zou Shichao, Jiangsu University of Science and Technology, 2012), "Optimization Research on Foam Aluminum Sandwich Plate Reinforced Mountain Cross-debris Flow Bridge Pier Impact-resistant Structure" (Wang Dongpo et al., Vibration and Shock, 2016, Vol. 35, No. 10), and "Optimization Research on Double-layer Foam Aluminum Sandwich Plate Anti-rolling Stone Impact Structure Performance" (Cheng Peng et al., Vibration and Shock, 2018, Vol. 37, No. 5) all disclose the application and design of steel-energy dissipation core composite sandwich structure in the anti-collision safety of specific buildings / structures. These existing technologies have two common characteristics: first, in the design of anti-collision performance, only the design of energy dissipation core is emphasized, and the energy dissipation effect of steel plate as part of the composite sandwich structure when impacted is ignored. Therefore, the energy dissipation performance of the complete composite sandwich structure is underestimated, resulting in conservative design. Second, in the anti-collision test or energy dissipation component design, the problem of measuring the energy dissipation deformation of steel plate is not solved, that is, only physical measurement means is used to determine the deformation degree of steel plate, and no mathematical method is given to measure the energy dissipation deformation of steel plate under impact. Therefore, the existing technology has not solved the problem of mathematical quantification of the energy dissipation deformation process of steel plate using key parameters, which is inconsistent with the engineering practice of large-scale use of steel plate in anti-collision buildings / structures, and restricts the improvement of the scientificity of the design method of anti-collision body / anti-collision part / anti-collision device with steel plate as the impact surface. SUMMARY

[0004] The present application aims at the deficiencies of the prior art, and provides a method for measuring the deformation process of a steel plate under impact, and a design method for a rockfall collision prevention device using the method.

[0005] To achieve the above-mentioned object, the present application first provides a method for measuring the energy dissipation deformation of a steel plate, and the technical solution is as follows:

[0006] The method for measuring the energy dissipation deformation of a steel plate measures the compressive strain ε(t) of the steel plate under impact by a spherical body, and is characterized in that the compressive strain ε(t) of the steel plate is calculated according to Formula 1,

[0007]

[0008] In Formula 1, ε(t) is the compressive strain of the steel plate,

[0009] δ(t) is the impact indentation depth of the steel plate, which is determined according to an impact test,

[0010] R1 is the radius of the spherical body.

[0011] The above-mentioned method is to measure the compressive strain caused by the compressive small deformation of the steel plate due to the elastic-plasticity of the material under impact. The impact object is a homogeneous spherical body, or an object that can be approximately regarded as a homogeneous spherical body according to the prior art. The data of the impact indentation depth δ(t) of the steel plate required for measuring the compressive strain ε(t) can be obtained through the existing impact test.

[0012] On the basis of measuring and determining ε(t), the method of the present application further provides a method for calculating the radius R2(t) of the deformation zone of the steel plate according to Formula 2, and a method for calculating the volume V1(t) of the deformation zone of the steel plate according to Formula 3, wherein d1 is the original thickness of the impact zone of the steel plate.

[0013]

[0014]

[0015] In the above-mentioned technical solution for measuring the energy dissipation deformation of a steel plate, the units of the variables are not specified, because the measurement mainly involves physical distance indicators, and different units can be specified in different measurement conditions, as long as the dimensions on both sides of the equation are balanced.

[0016] By measuring the energy dissipation deformation characteristics of the steel plate, the anti-impact performance of the steel plate can be evaluated. The anti-impact performance of various anti-collision bodies with a steel plate as the impact layer can also be evaluated. Therefore, the present application provides the following application technical solutions:

[0017] Application of the above-mentioned method for measuring the energy dissipation deformation of a steel plate in the evaluation of the anti-impact performance of the steel plate.

[0018] The application of the steel plate energy consumption deformation measurement method in the anti-collision body energy consumption performance measurement and evaluation, characterized in that: the collision-impinging layer of the anti-collision body is a steel plate layer.

[0019] The anti-collision performance measurement and evaluation referred to in the above application type technical solution can include the deformation degree, deformation energy consumption level, and failure damage degree of the steel plate or anti-collision body under impact. The impact object should be a homogeneous spherical body, or an object that can be considered as a spherical body by using existing technology.

[0020] The above technical solution measures the deformation process of the steel plate under impact. When the steel plate deformation process reaches the limit state, the compression strain ε(t) in the measurement scheme is expressed as the steel plate failure strain ε f At this time, the effective energy absorption volume of the steel plate can be measured and determined Further, the deformation energy consumption of the steel plate under impact can be measured. The present application provides a steel plate deformation energy consumption measurement method, and the technical solution is as follows:

[0021] A steel plate deformation energy consumption measurement method for measuring the energy consumption of a steel plate under impact by a spherical body, characterized in that: the limit deformation energy consumption W1 of the steel plate is measured according to formula 4,

[0022]

[0023]

[0024] In formula 4 and formula 5, W1 is the limit deformation energy consumption of the steel plate,

[0025] EA1 is the energy consumption value per unit volume of the steel plate, which is measured and determined according to existing technology,

[0026] is the effective energy absorption volume of the steel plate,

[0027] d1 is the original thickness of the impact area of the steel plate, which is determined by material performance,

[0028] R1 is the radius of the spherical body, which is determined by field data,

[0029] ε f is the failure strain of the steel plate, which is determined by material performance.

[0030] The present application provides the following application type technical solutions:

[0031] The application of the above steel plate deformation energy consumption measurement method in the anti-collision performance measurement and evaluation.

[0032] The application of the above steel plate deformation energy consumption measurement method in the anti-collision body energy consumption performance measurement and evaluation, characterized in that: the collision-impinging layer of the anti-collision body is a steel plate layer.

[0033] A common structure of the anti-collision body of the engineering structure is a composite sandwich structure as an energy dissipation part. The composite sandwich structure mainly utilizes the deformation of the energy dissipation core material to dissipate energy, and simultaneously covers the steel panel outside the energy dissipation core material as a collision surface. The steel panel can protect the energy dissipation core material from being directly abraded, weathered and corroded, can expand the deformation zone of the energy dissipation core material to increase the energy dissipation amount, and can also dissipate energy through its own deformation to share the total energy dissipation amount. The application provides an energy dissipation amount measurement method for the anti-collision body, and the technical scheme is as follows:

[0034] An anti-collision body impact energy dissipation amount measurement method realized by using the above-mentioned steel plate deformation energy dissipation amount measurement method, characterized in that:

[0035] The energy dissipation part of the anti-collision body is a composite sandwich structure, which includes a steel panel as a collision surface and an energy dissipation core material;

[0036] The limit deformation energy dissipation amount W1 of the steel panel is measured and calculated,

[0037] The deformation energy dissipation amount W2 of the energy dissipation core material is measured and calculated according to formula 6 and formula 7, and the deformation zone radius of the energy dissipation core material is It is determined according to formula 6,

[0038] W2=EA2×V2 formula 6

[0039]

[0040] In formula 6 and formula 7, W2 is the limit deformation energy dissipation amount of the energy dissipation core material,

[0041] EA2 is the energy dissipation value per unit volume of the energy dissipation core material, which is determined according to the material properties,

[0042] V2 is the effective energy absorption volume of the energy dissipation core material, which is determined according to According to the prior art,

[0043] The deformation zone radius of the energy dissipation core material,

[0044] The impact energy dissipation amount W of the anti-collision body is determined according to formula 8,

[0045] W=W1+W2 formula 8.

[0046] The above-mentioned anti-collision body energy dissipation amount measurement method measures the energy dissipation amount W of the energy dissipation part of the anti-collision body when impacted. The method is based on the above-mentioned steel plate impact deformation measurement scheme of the application, and measures the limit deformation zone radius of the steel panel as a collision surface, so as to measure the deformation zone radius of the energy dissipation core material Thus, the total energy dissipation amount of the composite sandwich structure is measured.

[0047] The premise for the above-mentioned energy consumption measuring method of the anti-collision body to be applicable is that the radius of the limit deformation zone of the steel panel can be reasonably regarded as the radius of the deformation zone of the energy consumption core material thereafter, and the specific condition is that the strength of the buffer material under the steel panel is less than the strength of the steel panel, thus requiring the strength of the energy consumption core material to be less than the strength of the steel panel.

[0048] Another object of the present application is to provide a design method of the rockfall anti-collision device, which solves the structure design problem of the energy consumption component.

[0049] A design method of the rockfall anti-collision device realized by the above-mentioned energy consumption measuring method of the anti-collision body, characterized in that: the installation position of the energy consumption component of the rockfall anti-collision device and the maximum impact energy W' of the rockfall are determined according to the field investigation data, the energy consumption component of the rockfall anti-collision device is a composite sandwich structure, the shape of the rockfall is converted into an equivalent spherical shape with a radius R1, the impact energy consumption W of the energy consumption component of the rockfall anti-collision device is measured by using the energy consumption measuring method of the anti-collision body, and the design parameters of the energy consumption part of the rockfall anti-collision device are calculated according to the size relationship between W and W'.

[0050] The impact damage of the rockfall to the building body / structure body is related to the terrain where the building body / structure body is located, and the basic data such as the impact position and the impact energy of the rockfall can be obtained through field investigation. For the building body / structure body, the energy consumption component is installed at the possible rockfall impact position and the designed energy consumption of the energy consumption component is ensured to meet the maximum impact energy of the rockfall at that position, which is an effective design scheme of the anti-collision device. If the above-mentioned composite sandwich structure is used as the energy consumption component, the impact energy consumption W of the energy consumption component can be measured by using the anti-collision body energy consumption measuring method, and the design of the rockfall anti-collision device can be performed.

[0051] Compared with the prior art, the present application has the following advantages: (1) The technical scheme for measuring the energy consumption deformation of the steel panel can measure three key parameters, i.e. the compression strain, the deformation zone radius and the deformation zone volume, in the plastic deformation process of the steel panel impacted by a spherical body, thereby quantifying the energy consumption deformation process of the steel panel. The defects of the prior art that the strain response of the impact deformation process of the steel panel can only be represented by the experimental measurement result curve and the impact deformation zone of the steel panel can only be measured but cannot be calculated are overcome. (2) The technical scheme for measuring the energy consumption of the steel panel impacted by a spherical body is a technical problem that the prior art has not solved. (3) Based on the function of the impact deformation measurement of the steel panel, the scientificity of the energy consumption effect measurement scheme of the prior art for the steel panel-energy consumption core material sandwich composite component (i.e. the composite sandwich structure) is improved, the energy consumption efficiency of the impact steel panel in the component can be scientifically measured, and the waste caused by the conservative design due to only measuring the energy consumption effect of the energy consumption core material is reduced. (4) The rockfall anti-collision device design method of the present application can make the engineering design meet the anti-collision energy consumption target by selecting and combining more material parameters in the anti-collision body, thereby improving the flexibility and practicality of the design method. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of a test platform for spherical impact on a steel plate.

[0053] Figure 2 It is the impact acceleration time history curve.

[0054] Figure 3 It is the equation for fitting the impact acceleration time history curve.

[0055] Figure 4 This is a schematic diagram of the external structure of the bridge pier anti-collision device.

[0056] Figure 5 This is a schematic diagram of the energy-consuming components of the bridge pier anti-collision device.

[0057] The numbers in the attached diagram are labeled as follows:

[0058] 1. Composite sandwich structure; 11. Steel panel; 12. Energy-dissipating core material; 121. Foamed aluminum layer; 122. Polyurethane layer; 13. Backing plate; 2. Pier body. Detailed Implementation

[0059] The preferred embodiments of the present invention will now be further described with reference to the accompanying drawings.

[0060] Example 1

[0061] like Figures 1-3 As shown, the energy-consuming deformation of a steel plate is measured using the method of the present invention.

[0062] The impact indentation variable of the steel plate was obtained by using a spherical impact test, and the compressive strain ε(t) of the steel plate during the impact process was measured.

[0063] Figure 1 This is a schematic diagram of a spherical impact testing platform for steel plates. The main body of the platform is a steel truss structure, equipped with necessary drop hammer lifting devices, pressure monitoring devices, high-speed camera devices, data acquisition devices, and a data processing and analysis center. The drop hammer is positioned high on the platform and falls to impact the steel plate at the bottom of the platform. The drop hammer is spherical, made of bearing steel, with a radius R1 = 0.125m, a weight of 63.3kg, and a drop height of 4m. The steel plate is rectangular, made of Q235 steel, with a density of 7850kg / m³. 3 The thickness is 2.5 mm. The entire test process was recorded using a high-speed camera, and the time history curve of the falling hammer impact acceleration was extracted.

[0064] Using the impact acceleration time history curve, the impact acceleration a function of the sphere is established according to Equation 9, and the impact indentation depth δ(t) function of the steel plate is established according to Equations 10 and 11. In Equations 9 to 11, t is the impact time (s), A, B, C, D, and E are experimental parameters, and v(t) is the impact velocity time history of the sphere.

[0065] a = At 4 +Bt 3 +Ct 2 +Dt+E Equation 9

[0066]

[0067]

[0068] a = -7.5 x 10 8 t 4 +7.6 x 10 7 t 3 -1.8 x 10 6 t 2 -7.3 x 10 3 t+94.0 (Equation 9-1), by 2 times integral, δ(t) = -2.5 x 10 7 t 6 +3.8 x 10 6 t 5 -1.5 x 10 5 t 4 -1.2 x 10 3 t 3 +47t 2 (Equation 10-1). Figure 2 is the impact acceleration time history curve, Figure 3 is the impact acceleration time history curve fitting equation.

[0069] Substitute δ(t) into Equation 1, Equation 2, Equation 3 to measure the compression strain ε(t) of the steel plate, the radius R2(t) of the steel plate deformation zone and the volume V1(t) of the steel plate deformation zone, respectively.

[0070] Taking the impact time T = 0.025s as an example, substitute t = 0.025 into Equation 9-1, 10-1, and then into Equation 1-3, and have ε(T) = 0.017m, R2(T) = 0.063m, V1(T) = 2.52*10 -5 m 3 . The calculation result is within the engineering design acceptable range compared with the measured data.

[0071] Example Two

[0072] As Figure 4 , Figure 5 shown, the energy dissipation efficiency of the bridge pier anti-collision device designed by the method of the application.

[0073] 1. Field investigation to obtain basic data

[0074] The field investigation determines the pier body specifications (pier body cross section is capsule-shaped), the rockfall impact location (impact angle, maximum jump height), the maximum possible size of the rockfall (equivalent sphere radius R1 = 0.25 m), the maximum possible impact energy W' = 100 kJ (rockfall density 2700 kg / m 3 , equivalent weight 176.6 kg, impact pier body speed 33.72 m / s).

[0075] 2. Bridge pier anti-collision device design

[0076] Figure 4 is a schematic diagram of the external structure of the bridge pier anti-collision device, Figure 5 is a schematic diagram of the energy dissipation structure of the bridge pier anti-collision device (the arrow shows the impact direction).

[0077] According to the characteristics of the rockfall impact location, the energy dissipation structure is designed to be arranged around the outer periphery of the pier body 2. The energy dissipation structure adopts a composite sandwich structure 1 which wraps around the four sides of the pier body 2. The composite sandwich structure 1 includes a steel panel 11 as the impact surface, an energy dissipation core material 12, and a back plate 13 which is tightly attached to the outer surface of the pier body 2 and is filled with mortar. The steel panel 11 compacts and fixes the energy dissipation core material 12 between the steel panel 11 and the back plate 13. The energy dissipation core material 12 is a composite layer of a foamed aluminum layer 121 and a polyurethane layer 122, which are tightly attached or bonded to each other, and the foamed aluminum layer 121 is tightly attached to the steel panel 11. The composite sandwich structure 1 has necessary sealing strips / plates in the cross section.

[0078] The steel panel 11 adopts steel plate Q235 with a thickness d1 = 5 mm, a yield strength σ y = 235 MP, a yield strain ε y = 0.001, and a failure strain ε f = 0.3.

[0079] The foamed aluminum material has a density ρ 21 = 300 kg / m 3 , a unit volume energy absorption value EA 21 = 2.89 * 10 6 J / m 3 , and a thickness d 21 = 0.15 m.

[0080] The polyurethane material has a density ρ 22 = 60 kg / m 3 , a unit volume energy absorption value EA 22 = 0.23 * 10 6 J / m 3 , and a thickness d 22 = 0.05 m.

[0081] 3. Checking the safety of the energy dissipation design of the bridge pier anti-collision device

[0082] According to existing technology (Equation 12), the energy consumption per unit volume of steel plate is calculated as EA1 = 70.38 * 10 6 J / m 3 Calculate the effective energy absorption volume of the steel panel 11 according to Formula 5. According to Equation 4, the energy consumed by the ultimate deformation of steel panel 11 is calculated to be W1 = 48.84 kJ.

[0083]

[0084] Calculate the radius of the deformation zone of the energy-consuming core material 12 according to Formula 7. In extreme cases, the rolling stone penetrates the aluminum foam layer 121 after penetrating the steel panel 11, and then penetrates the subsequent polyurethane layer 122. Therefore, the radius of the deformation zone between the aluminum foam layer 121 and the polyurethane layer 122 in extreme cases... The values ​​are the same. The effective energy absorption volume V of the aluminum foam layer is calculated according to existing technology (Equation 13). 21 =2.08*10 -2 m 3 Effective energy absorption volume V of polyurethane layer 22 =6.92*10 -3 m 3 Calculate the energy consumption W for the ultimate deformation of the aluminum foam layer according to Equation 6. 21 =60.11kJ, Energy consumed by lamination deformation of polyurethane (W) 22 =1.59kJ.

[0085]

[0086] In Equation 10, d is the thickness of the energy-consuming core material (aluminum foam layer d). 21 or polyurethane layer d 22 ).

[0087] The energy consumption W2 during deformation of the energy-consuming core material 12 is the energy consumption W during deformation of the aluminum foam layer 121. 21 Energy consumption W for deformation of polyurethane layer 122 22 The sum of W2 = W 21 +W 22 =60.11 + 1.59 = 61.70 kJ.

[0088] According to Equation 8, the deformation energy dissipation of the composite sandwich structure is calculated to be W = 110.54 kJ.

[0089] Since W′≤W, the design parameters of the composite sandwich structure 1 meet the energy consumption design standard.

[0090] Using W′≤W as the energy dissipation design standard for each energy-consuming component, this can also guide the design of the material performance index combination for the composite sandwich structure 1 that meets the energy dissipation design standard. The material performance index includes material performance parameters related to the deformation volume characteristics and deformation energy dissipation characteristics of each layer of the composite sandwich structure 1.

Claims

1. A method for measuring the energy dissipation of a steel sheet by measuring the compressive strain of a steel sheet during a deformation process caused by a spherical body impact ε t characterized in that: The compressive strain of the steel plate is calculated by Equation 1 ε t ),​ ​ Formula 1 In formula 1, ε t ) - compressive strain of the steel plate; R 1 - radius of the sphere, unit: m; δ t ) - impact indentation depth of the steel plate, determined according to the impact test, specifically, the time history curve of the sphere impact acceleration is collected by using the sphere impact acceleration test platform to impact the steel plate test platform, the sphere impact acceleration function is established according to formula 9, the impact indentation depth of the steel plate is established according to formula 10 and formula 11 a δ t ) function,​​​​ Formula 9 Formula 10 Formula 11 in formulae 9 to 11, t - impact time, in s; A , B , C , D , E - test parameters; v ( t ) - sphere impact velocity time history, in m / s; The radius of the deformation zone of the steel plate is calculated according to equation 2 R 2(t), Formula 2 In formula 2, R 2( t ) - radius of the steel sheet deformation zone, in m; The volume of the deformed zone of the steel plate is calculated by Equation 3 V 1( t ), Formula 3 in formula 3, V 1( t ) - volume of the deformed zone of the steel sheet, in m 3 ; d 1 - original thickness of the impact zone of the steel sheet, in m; Limiting deformation energy of steel plate impacted by spherical body is calculated according to formula 4, formula 5 W 1, Formula 4 Formula 5 in formula 4, formula 5, W 1 - Steel plate ultimate deformation energy dissipation, unit kJ; EA 1 - Steel plate energy absorption per unit volume, unit kJ / m 3 , determined according to the prior art; V εf - Steel plate effective energy absorption volume, unit m 3 ; d 1 - Steel plate impact zone original thickness, unit m, determined according to material properties; R 1 - Spherical body radius, unit m, determined according to field data; ε f - Steel plate failure strain, determined according to material properties.

2. The method of claim 1, wherein the energy absorption capacity of the crash body is measured, characterized in that: the energy absorption element of the crash body is a composite sandwich structure (1) comprising a steel panel (11) as a crash surface and an energy absorption core (12); Estimating the energy dissipated by the ultimate deformation of a steel panel (11) W 1, The limit deformation energy dissipation of the energy dissipation core material (12) is calculated according to the formula 6 and the formula 7 W 2, Formula 6 Formula 7 in formula 6, formula 7, W 2 - Limiting deformation energy dissipation of energy-consuming core material, unit: kJ; EA 2 Energy absorption value per unit volume of energy dissipation core, unit kJ / m 3 , determined according to the material properties; V 2 Effective energy absorption volume of energy consumption core, unit m 3 , according to R 2εf determined; R 2εf - radius of the energy dissipating core deformation zone, in m; Determining the energy absorbed by the crash body upon impact according to equation 8 W , Formula 8.

3. The method of claim 2, wherein: The energy dissipation core material (12) is a composite layer of a foamed aluminum layer (121) and a polyurethane layer (122), the foamed aluminum layer (121) is close to the steel panel (11); the deformation zone radius of the foamed aluminum layer (121) and the polyurethane layer (122) is R 2εf The limit deformation energy dissipation amount W2 of the energy dissipation core material (12) is the sum of the limit deformation energy dissipation amount W 21 of the foamed aluminum layer (121) and the limit deformation energy dissipation amount W 22 of the polyurethane layer (122).

4. The design method of rockfall collision avoidance device using the measurement method of claim 3, characterized in that: According to the field investigation data, the installation position of the rockfall energy dissipation device and the maximum impact energy of the rockfall are determined W' , the energy dissipation device of the rockfall protection device is a composite sandwich structure (1), which converts the shape of the rockfall into an equivalent spherical shape with a radius R 1, and the impact energy dissipation of the energy dissipation device of the rockfall protection device is calculated W , and W' ≤ W is the design standard of the energy dissipation device.

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