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Steel pipe bending strength calculator - steel pipe bending strength calculation formula

Views: 7     Author: Site Editor     Publish Time: 2025-02-05      Origin: Site

The calculation formula of steel pipe bending strength can be derived and obtained through Euler's formula. Euler's formula is a theoretical model established by Euler through analyzing the bending instability model of rods under compression and tension. The formula for calculating bending strength is based on this model. The calculation formula of bending strength is: M = σ * W = (π^2 * E * I) / L^2, where M represents the bending moment that the steel pipe can withstand, σ represents the stress that the steel pipe can withstand, W represents the section modulus of the steel pipe, E represents the elastic modulus of the material, I represents the moment of inertia of the section of the steel pipe, and L represents the length of the steel pipe. It should be noted that when calculating the bending strength, in addition to the properties of the material, it is also necessary to consider the geometric factors and support conditions in the steel pipe. For example, when the cross-sectional shape of the steel pipe is circular and square, the moment of inertia and section modulus of the section will also change accordingly, which will affect the calculation of the bending strength of the steel pipe.


Therefore, in practical applications, it is necessary to select different formulas for calculation according to specific circumstances, and analyze them in combination with the specific environment and use conditions of the steel pipe to ensure the safety and reliability of the steel pipe. In addition, there are some other formulas for calculating the bending strength of steel pipes, such as the formula for calculating the bending strength using the moment of inertia of unequal cross-sections, etc. These formulas are all calculation methods derived from different situations and needs, and they need to be carefully considered when selected.


First, the meaning of bending strength

Bending strength refers to the ability of a material to resist bending without breaking and is mainly used to examine the strength of brittle materials such as ceramics. Generally, a three-point bending test or four-point test method is used for evaluation. Among them, the four-point test requires two loading forces, which is more complicated; the three-point test is most commonly used. Its value is proportional to the maximum pressure it bears. Bending strength (bending strength) bending strength.


Second, the details of the test elements

1. Mechanical properties: various mechanical properties exhibited when the material is subjected to external force.

2. Stress: the reaction of the material to the external force when the material is subjected to external force. The magnitude of stress is expressed by the following formula: stress (δ) = action (F) / unit area of material (A), in units of Pa.

3. Strain: deformation caused by external force on the material. The magnitude of strain is expressed by the following formula: strain (ε) = change length (△L) / initial length (L).

4. Tensile stress or tensile stress (tensile stress): internal stress of the material when it is stretched.

5. Compressive stress or compressive stress (compressive stress): internal stress of the material when it is compressed.

6. Shear stress (shear stress): internal stress when the parallel parts of the material slide when the material is subjected to shear force. However, when a certain section of material or restoration is subjected to force, three forms of stress often exist at the same time. For example, when chewing pressure acts on a fixed bridge, the force on the gingival surface of the bridge is compressive stress, the gingival bottom of the bridge is tensile stress, and the connection between the abutment restoration and the bridge is shear stress.

7. Tensile strength or tensile strength (tensile strength)

8. Compression strength or compressive strength (compressive strength): Apply a compressive load to the specimen until the unit area load value when the specimen is destroyed.

9. Bending strength (bending strength): also known as flexural strength or bending strength, apply a load between the two supporting points of the specimen until the unit area load value when the specimen is destroyed.


Third, details of the calculation formula

Three-point test bending formula:

R= (3F*L)/ (2b*h*h)

F—Failure load

L—Span

b—Width

h—Thickness


Fourth, about the test method of steel pipes

The national standard for bending strength (GB/T 6569-86), or ISO 14704-2000 test sample (35 × 3 × 4) standard is shown in the following figure "Test Method". The bending strength test is divided into three-point bending and four-point bending. Each point requires more than 5 data (standard requires 10 data) and averages the results. As shown in the figure "Bending Strength". The bending strength test was carried out on the British Instron1195 universal material testing machine. The test bar used for the test was 3×4×35 (mm*mm*mm). The three-point bending method was used for measurement, with a span of 30mm and a loading rate of 0.5mm/min. Five test bars were tested for each data, and then the average value was taken.


Fifth, the calculation formula for the bending strength sy of steel pipes

As a common structural material, the bending strength of steel pipes is one of the important indicators for evaluating their bearing capacity. The bending strength sy of steel pipes can be calculated by the following formula: sy = M / S.

Where sy represents the bending strength of the steel pipe, M represents the bending moment acting on the steel pipe, and S represents the section modulus of the steel pipe. In actual engineering, we need to determine the bending strength of the steel pipe according to the specific situation. The following will explain in detail how to calculate the bending strength of the steel pipe through a case.


Suppose we have a round steel pipe with a diameter of 50mm, a wall thickness of 5mm, and a length of 2m. Now we need to calculate the bending strength of the steel pipe when it is subjected to a bending moment. We need to calculate the section modulus S of the steel pipe. For a round steel pipe, its section modulus can be calculated by the following formula: S = (π/32) * (D^4 - d^4). Where D represents the outer diameter and d represents the inner diameter. Substituting the specific values, we have: S = (π/32) * ((50^4) - (40^4)) = 1.5e7 mm^3. Next, we need to determine the bending moment M acting on the steel pipe. Assume that a bending moment of 1000 N·m is applied to the middle point of the steel pipe. Substituting the formula, we can calculate the bending strength sy of the steel pipe: sy = M / S = (1000 N·m) / (1.5e7 mm^3) ≈ 0.067 N/mm^2. In this way, we get the bending strength of the steel pipe when it is subjected to a bending moment of 1000 N·m, which is 0.067 N/mm^2.


It should be noted that the above calculation results are only applicable to the steel pipe in this specific case. In actual engineering, we need to calculate the bending strength of the steel pipe based on specific material parameters and structural requirements. At the same time, other factors such as bending form, support conditions, etc. should also be considered. The bending strength of the steel pipe is one of the important indicators for evaluating its bearing capacity. By reasonable calculation and selection of appropriate material parameters, we can ensure that the steel pipe has sufficient bending resistance when subjected to bending moment, thereby ensuring the safety and reliability of the project.

Hunan Great Steel Pipe Co.,Ltd
Hunan Great Steel Pipe Co.,Ltd is a world-class production and service provider of submerged arc straight seam welded pipe as the first subsidiary of Shinestar Group. Hunan Great Steel Pipe Co.,Ltd pays more attention to in the pipeline engineering research areas as a pioneer of China Petroleum Pipeline & Gas Pipeline Science Research Institute.

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