A cable structure with thermal protection performance and its design method

Abstract

The present invention discloses a cable structure with thermal protection performance and a design method thereof. The cable structure includes a cable body and materials 1, 2, and 3 arranged in sequence on the outside of the cable body to form a cable structure with thermal protection performance. Material 1 is a low thermal conductivity material, and materials 2 and 3 are selected according to the structural dimensions. By adjusting the radius R1 of material 1, the radius R2 and thermal conductivity k2 of material 2, and the radius R3 and thermal conductivity k3 of material 3, the selection range of thermal conductive materials is broadened, and it is applicable to cable bodies of different radii, and the fireproof effect of the cable with thermal protection performance is adjusted. The design method of the cable structure with thermal protection performance proposed by the present invention has a simple structure and is easy to manufacture. It provides a new way to control heat transfer, effectively reduces the impact of external high temperature on the cable body, and provides a new idea for fire protection of bridges and other cable systems, with good application prospects.

Description

Technical Field

[0001] The invention relates to a design method of a cable structure with heat protection performance, belonging to the technical field of cable fire protection. Background Art

[0002] Cable-stayed bridges and suspension bridges are characterized by their large spans and beautiful appearance. They are widely used in bridge construction. While the volume of transportation has increased significantly, the risk of vehicle fire accidents has also increased. Fires and explosions will cause immeasurable damage to bridges under the extreme loads that bridges may bear. Cables are important load-bearing components of cable-supported bridges. When a fire occurs on the bridge deck (especially a tanker fire), the cable system will be affected by heat convection and heat radiation, which can easily cause the PE sheath of the suspension cable to burn, and the temperature of the steel wire will continue to rise, leading to fire damage such as the peeling of the anti-corrosion layer and the degradation of steel wire performance. The elastic modulus and ultimate bearing capacity of the cable also decrease with rising temperature, posing a serious threat to the safe operation of the bridge.

[0003] At present, relevant specifications for the fire protection of cable components have not yet been formulated. The fire protection design of cable components mainly refers to relevant achievements in the field of building steel structures. By using fire-proof materials with high-temperature resistance, heat resistance and flame retardant properties, the damage caused by fire to bridges can be reduced. However, existing fire-proof materials have problems such as low fire resistance level, high-temperature resistance and insufficient thermal conductivity. New ways are needed to control heat transfer near the cables and reduce the impact of fire accidents on the cable body. Summary of the Invention

[0004] Technical issues:

[0005] The present invention aims to at least partially address one of the technical problems existing in the related art. To this end, the present invention provides a method for designing a cable structure with thermal protection properties. By placing low thermal conductivity material 1, materials 2 and 3 with different thermal conductivities on the exterior of the cable, a cable structure with thermal protection properties is formed. This structure is simple and easy to manufacture, providing a new approach to heat transfer control and effectively reducing the impact of high temperatures on the cable. This offers a novel approach to fire protection for bridges and other cable systems, and has promising application prospects.

[0006] Technical solution:

[0007] A cable structure with thermal protection performance includes a protected cable body and a first material, a second material, and a third material disposed in sequence on the outside of the cable body; the first material is a low thermal conductivity material with a thermal conductivity coefficient k1 of 0.001 to 0.1 W / (m·K); the relationship between the thermal conductivity coefficients of the three materials and the radius is given by the following formula:

[0008]

[0009] Wherein, β=k2 / k3, R1, R2, and R3 are the outer diameters of the first material, the second material, and the third material respectively, k is the ambient thermal conductivity, k2 is the thermal conductivity of the second material, and k3 is the thermal conductivity of the third material.

[0010] Preferably, the protected cable body is a steel cable or a CFRP cable.

[0011] Preferably, the first material is polystyrene, ceramic fiber, rock wool or aerogel composite material.

[0012] Preferably, the second material and the third material are carbon fiber, polycarbonate or rainproof neoprene.

[0013] Preferably, when β=1, the thermal conductivity k2 of the second material and the thermal conductivity k3 of the third material are given by the following formula:

[0014]

[0015] The present invention also provides a design method for a three-layer cable structure, comprising the following steps:

[0016] Step 1: Determine the environmental thermal conductivity k, select the first material, the second material, and the third material, determine the thermal conductivity k1 of the first material, the thermal conductivity k2 of the second material, and the thermal conductivity k3 of the third material, and calculate β;

[0017] Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the third material;

[0018] Step 3: Determine the outer diameter R1 of the first material and calculate the outer diameter R2 of the second material according to formula (1).

[0019] The present invention also provides a design method for a two-layer cable structure, comprising the following steps:

[0020] Step 1: Determine the environmental thermal conductivity k, select the first material and the second material, determine the thermal conductivity k1 of the first material and the thermal conductivity k2 of the second material, and set β = 1;

[0021] Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the second material;

[0022] Step 3: Determine the outer diameter R1 of the first material and calculate the outer diameter R2 of the second material according to formula (2).

[0023] Beneficial effects:

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] (1) The cable structure with heat protection performance proposed in the present invention can greatly reduce the impact of external high temperature on the cable body. In a continuous high temperature environment, heat is transmitted around the cable body, and the temperature of the cable body remains basically unchanged, providing a new way to control heat transmission and a new idea for cable fire prevention.

[0026] (2) The cable structure with thermal protection performance proposed in the present invention can broaden the selection range of thermal conductive materials by changing the radius R1 of material 1, the radius R2 and thermal conductivity k2 of material 2, and the radius R3 and thermal conductivity k3 of material 3, and can more flexibly construct cable structures suitable for different cable body radii.

[0027] (3) The cable structure with heat protection performance proposed by the present invention has a simple structure and is easy to prepare.

[0028] (4) The cable structure with thermal protection performance proposed in the present invention can be applied to, but not limited to, cable structures in bridges, and is also applicable to other cable systems that require protection, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of a three-layer cable structure with thermal protection performance according to an embodiment of the present invention.

[0030] Figure 2 Schematic diagram of a two-layer cable structure with thermal protection performance according to an embodiment of the present invention.

[0031] Figure 3 FIG. 1 is a curve showing temperature variation over time of a cable body of a two-layer cable structure with thermal protection performance according to an embodiment of the present invention.

[0032] Figure 4 1 is the isothermal line of the cable body of the two-layer cable structure with thermal protection performance according to an embodiment of the present invention.

[0033] Figure 5 Graphs 1 and 2 show the temperature fields of the cable body at different times of a two-layer cable structure with thermal protection performance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be described in more detail below with reference to schematic diagrams, which illustrate preferred embodiments of the present invention. It should be understood that those skilled in the art may modify the present invention as described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as a general guide for those skilled in the art and not as a limitation of the present invention.

[0035] A design method for a cable structure with thermal protection performance according to an embodiment of the present invention will be further described below with reference to the accompanying drawings.

[0036] like Figure 1As shown, a cable structure with thermal protection performance is proposed according to an embodiment of the present invention. The three-layer cable structure includes: a cable body, and material 1, material 2, and material 3 arranged in sequence on the outside of the cable body. The cable body radius is R0, the outer diameter of material 1 is R1, the outer diameter of material 2 is R2, and the outer diameter of material 3 is R3.

[0037] When the outer side of the cable body in the cable structure is made of three materials, the design method includes the following steps:

[0038] Step 1: Determine the environmental thermal conductivity k, select the first material, the second material, and the third material, determine the thermal conductivity k1 of the first material, the thermal conductivity k2 of the second material, and the thermal conductivity k3 of the third material, and calculate β;

[0039] Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the third material;

[0040] Step 3: Determine the outer diameter R1 of the first material and calculate the outer diameter R2 of the first material according to formula (1).

[0041]

[0042] When the outer side of the cable body in a cable structure is made of two materials, the design method includes the following steps:

[0043] Step 1: Determine the environmental thermal conductivity k, select the first material and the second material, determine the thermal conductivity k1 of the first material and the thermal conductivity k2 of the second material, and set β = 1;

[0044] Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the second material;

[0045] Step 3: Determine the outer diameter R1 of the first material and calculate the outer diameter R2 of the second material according to formula (2).

[0046]

[0047] like Figure 2 As shown, this embodiment provides a two-layer cable structure, including a cable body, material 1, and material 2, and constructs a finite element model of the cable structure with thermal protection performance. The cable body radius is R0 = 0.1m, and the radius of material 1 is R1 = 0.125m. Among them, the cable body is a steel cable with a density of ρ0 = 7850kg / m 3 , thermal conductivity k0 = 44.5W / (m·K), constant pressure heat capacity C p0 =475J / (kg·K); Material 1 is polystyrene, density ρ1 = 40kg / m 3 , thermal conductivity k1=0.04W / (m·K), constant pressure heat capacity C p1=1300J / (kg·K); Material 2 is carbon fiber, density ρ2 = 1500kg / m 3 , thermal conductivity k2=0.2326W / (m·K), constant pressure heat capacity C p2 =800 J / (kg·K). A temperature load of 1000°C was applied to the bottom of the model, the initial temperature was set to 30°C, and the thermal conductivity of the environment was k = 0.076 W / (m·K).

[0048] Substituting the above relevant parameters into formula (2), the radius of material 2 is calculated to be R2 = 0.1375m.

[0049] like Figure 3 Figure 2 shows the cable temperature curve for a two-hour temperature load application. The initial cable temperature is 30°C. After one hour of temperature load application, the cable temperature reaches 30.07°C, a relatively gradual change. After two hours of temperature load application, the cable temperature reaches 30.56°C. Within one to two hours of temperature load application, the cable temperature changes significantly. Considering practical needs, the cable temperature after two hours of temperature load application is reasonable. Therefore, the thermally protected cable structure effectively reduces the impact of high temperatures on the cable.

[0050] like Figure 4 Figure 2 shows the isotherms of a cable structure model with thermal protection after two hours of combustion. The temperature of material 1 ranges from 535°C to 584°C, while the temperature of material 2 is between 584°C and 633°C on the side close to the temperature load and between 486°C and 535°C on the side away from the temperature load. The cable body remains relatively cool, around 30°C.

[0051] like Figure 5 The figure shows the temperature field of the cable structure model with thermal protection after burning for 30, 60, 90, and 120 minutes, respectively. As time passes, the ambient temperature gradually rises, and the temperature around the cable also gradually increases. The cable temperature is relatively low around 30°C, and heat is transferred around the cable body, achieving controlled heat transfer near the cable.

[0052] Finally, it should be noted that the accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual drawings, and should not be construed as limiting the present invention. To better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the dimensions of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions may be omitted in the accompanying drawings. The examples of the present invention are merely descriptions of preferred embodiments of the present invention and do not limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made to the technical solution of the present invention by engineers and technicians in this field should fall within the scope of protection of the present invention.

Claims

1. A cable structure with thermal protection performance, characterized in that: The cable comprises a protected cable body and a first material, a second material, and a third material sequentially arranged on the outside of the cable body; the first material is a low thermal conductivity material with a thermal conductivity coefficient k1 of 0.001 to 0.1 W / (m·K); the relationship between the thermal conductivity coefficients of the three materials and the radius is given by the following formula: Wherein, β=k2 / k3, R1, R2, and R3 are the outer diameters of the first material, the second material, and the third material respectively, k is the ambient thermal conductivity, k2 is the thermal conductivity of the second material, and k3 is the thermal conductivity of the third material.

2. A cable structure with thermal protection performance according to claim 1, characterized in that: The protected cable body is a steel cable or a CFRP cable.

3. A cable structure with thermal protection performance according to claim 1, characterized in that: The first material is polystyrene, ceramic fiber, rock wool or aerogel composite material.

4. A cable structure with thermal protection performance according to claim 1, characterized in that: The second material and the third material are carbon fiber, polycarbonate or rainproof neoprene.

5. The cable structure with heat protection performance according to claim 1, characterized in that: When β=1, the thermal conductivity k2 of the second material and the thermal conductivity k3 of the third material are given by the following formula:

6. The design method of the cable structure according to claim 1, characterized in that: The steps include: Step 1: Determine the environmental thermal conductivity k, select the first material, the second material, and the third material, determine the thermal conductivity k1 of the first material, the thermal conductivity k2 of the second material, and the thermal conductivity k3 of the third material, and calculate β; Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the third material; Step 3: Determine the outer diameter R1 of the first material and calculate the outer diameter R2 of the second material according to formula (1).

7. The design method of the cable structure according to claim 5, characterized in that: The steps include: Step 1: Determine the environmental thermal conductivity k, select the first material and the second material, determine the thermal conductivity k1 of the first material and the thermal conductivity k2 of the second material, and set β = 1; Step 2: Determine the radius R0 of the protected cable body and the outer diameter R3 of the second material; Step 3: Determine the outer diameter R1 of the first material and calculate the outer diameter R2 of the second material according to formula (2).

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