How to calculate the allowable shear force of screw
Shear force of bolt = shear strength of bolt * effective cross-sectional area of bolt (shear on one side, shear on both sides * 2); Stress section area of M12 bolt: 84.3 basic formula of bolt shear strength calculation: hope to help you, thank you
the pressure feed of the connected parts also needs to be inspected, the pressure feed force = pressure feed strength * aperture * plate thickness
the basic size of the unthreaded part of the reamed bolt is the same as that of the hole wall, which belongs to fit; However, the non threaded part of ordinary bolt is different from the basic size of hole wall, which does not belong to fit
according to the drawing, the reaming bolt and the hole wall are formed by a line; The common bolt and hole wall are composed of two lines
the maximum torque on the shaft / the distance between the universal joint fork and the neutral plane = shear force. Then calculate according to the above formula
from the perspective of raw materials:
high strength bolts are made of high strength materials. The screw, nut and washer of high-strength bolt are made of high-strength steel, commonly used
45 steel, 40 boron steel and 20 manganese titanium boron steel. Common bolts are usually made of Q235 steel
in terms of strength grade:
high strength bolts are widely used.
If No.45 steel is used, its 8.8 grade parameters are: minimum tensile strength 800-830mpa, Rockwell hardness 22-23, yield strength 640mpa. Only tensile strength should be considered for screws, and shear stress is generally ignored in practical engineering
I hope I can help you.
M1 bolt stress section area: 0.46
M2 bolt stress section area: 2.07
m3 bolt stress section area: 5.03
M4 bolt stress section area: 8.78
< P > M5 bolt stress section area: 14.2M6 bolt stress section area: 20.1
M8 bolt stress section area: 36.6
m10bolt stress section area: 58
M12 bolt Stress sectional area: 84.3
stress sectional area of M14 bolt: 115
stress sectional area of M16 bolt: 157
stress sectional area of M18 bolt: 192
stress sectional area of M20 bolt: 245
stress sectional area of M22 bolt: 303
stress sectional area of M24 bolt: 353
stress sectional area of M27 bolt: 459
stress sectional area of M30 bolt: 561
stress sectional area of M27 bolt M33 bolt stress section area: 694
M36 bolt stress section area: 817
M39 bolt stress section area: 976
II. Bolt code meaning
8.8 grade bolt meaning is bolt strength grade mark code from "•" It consists of two separated numbers. In the marking code "&" 8226; " Carbon steel: metric bolt mechanical property grade can be divided into: 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 13.5
1, bolt material nominal tensile strength of 800MPa The first 8)
2, the yield ratio of bolt material is 0.8 The second 8 is 0.8)
3. The nominal yield strength of bolt material is 800 × 3. The relationship between shear stress and tensile force has been proved by experiments. For general steel, the relationship between allowable shear stress and allowable tensile stress is as follows: plastic material [t] = 0.6-0.8 [b]; Brittle material [t] = 0.8-1.0 [b]
part stress value
the maximum stress value of parts or components in mechanical design or engineering structure design. In order to determine whether the working stress of a part or component is too high or too low after loading, it is necessary to determine a measurement standard in advance, which is the allowable stress. When the working stress of a part or component does not exceed the allowable stress, the part or component is safe in operation, otherwise it is unsafe. Allowable stress is the basic data in mechanical design and engineering structure design. In practical application, the allowable stress value is generally stipulated by the national engineering department according to the principles of safety and economy, material strength, load, environmental conditions, processing quality, calculation accuracy and the importance of parts or components. The allowable stress is equal to the failure stress (yield limit or strength limit in static strength design and fatigue limit in fatigue strength design) of the material after considering various influencing factors, divided by the safety factor. Plastic materials (most structural steels and aluminum alloys) are based on the yield limit, divided by the safety factor to obtain the allowable stress, i.e[ σ]=σ s/nn=1.5~2.5; For brittle materials (cast iron and high strength steel), the allowable stress is obtained by dividing the strength limit by the safety factor, i.e[ σ]=σ b/n(n=2~5)( N is the safety factor)
Stress sectional area of M6 nut: 20.1 square mm
so the shear stress = 50 * 9.8 / 20.1 = 24.38mpa. If the bolt is of grade 4.8, its tensile strength is 400MPa, and the shear strength is about half of the tensile strength, 200MPa
200 / 24.38 = 8.2, so the safety factor is large, no problem
{rrrrrrr}
the stress cross-sectional area of M1 bolt: 0.46
the stress cross-sectional area of M2 bolt: 2.07
the stress cross-sectional area of M3 bolt: 5.03
the stress cross-sectional area of M4 bolt: 8.78
the stress cross-sectional area of M5 bolt: 14.2
the stress cross-sectional area of M6 bolt: 20.1
the stress cross-sectional area of M8 bolt: 36.6
the stress cross-sectional area of M10 bolt: 58
the stress cross-sectional area of M12 bolt Stress section area of bolt: 84.3
stress section area of M14 bolt: 115
stress section area of M16 bolt: 157
stress section area of M18 bolt: 192
stress section area of M20 bolt: 245
stress section area of M22 bolt: 303
stress section area of M24 bolt: 353
stress section area of M27 bolt: 459
stress section area of M30 bolt: 5 61
M33 bolt stress section area: 694
M36 bolt stress section area: 817
M39 bolt stress section area: 976
II. Bolt code meaning
8.8 grade bolt meaning is bolt strength grade mark code by "•" It consists of two separated numbers. In the marking code "&" 8226; " Carbon steel: metric bolt mechanical property grade can be divided into: 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 13.5
1, bolt material nominal tensile strength of 800MPa The first 8)
2, the yield ratio of bolt material is 0.8 The second 8 is 0.8)
3. The nominal yield strength of bolt material is 800 × 3. The relationship between shear stress and tensile force has been proved by experiments. For general steel, the relationship between allowable shear stress and allowable tensile stress is as follows: plastic material [t] = 0.6-0.8 [b]; Brittle material [t] = 0.8-1.0 [b]
part stress value
the maximum stress value of parts or components in mechanical design or engineering structure design. In order to determine whether the working stress of a part or component is too high or too low after loading, it is necessary to determine a measurement standard in advance, which is the allowable stress. When the working stress of a part or component does not exceed the allowable stress, the part or component is safe in operation, otherwise it is unsafe. Allowable stress is the basic data in mechanical design and engineering structure design. In practical application, the allowable stress value is generally stipulated by the national engineering department according to the principles of safety and economy, material strength, load, environmental conditions, processing quality, calculation accuracy and the importance of parts or components. The allowable stress is equal to the failure stress (yield limit or strength limit in static strength design and fatigue limit in fatigue strength design) of the material after considering various influencing factors, divided by the safety factor. Plastic materials (most structural steels and aluminum alloys) are based on the yield limit, divided by the safety factor to obtain the allowable stress, i.e[ σ]=σ s/nn=1.5~2.5; For brittle materials (cast iron and high strength steel), the allowable stress is obtained by dividing the strength limit by the safety factor, i.e[ σ]=σ b/n(n=2~5)( N is the safety factor)
Calculation of bolt shear strength Basic formula
{rrrrrrr}
the stress section area of M1 bolt: 0.46
the stress section area of M2 bolt: 2.07
the stress section area of M3 bolt: 5.03
the stress section area of M4 bolt: 8.78
the stress section area of M5 bolt: 14.2
the stress section area of M6 bolt: 20.1
the stress section area of M8 bolt: 36.6
the stress section area of M10 bolt : 58
stress section area of M12 bolt: 84.3
stress section area of M14 bolt: 115
stress section area of M16 bolt: 157
stress section area of M18 bolt: 192
stress section area of M20 bolt: 245
stress section area of M22 bolt: 303
stress section area of M24 bolt: 353
stress section area of M27 bolt: 459
stress section area of M30 bolt Stress section area: 561
M33 bolt stress section area: 694
M36 bolt stress section area: 817
M39 bolt stress section area: 976
II. Bolt code meaning
< P > 8.8 grade bolt meaning is bolt strength grade mark code by "•" It consists of two separated numbers. In the marking code "&" 8226; " Carbon steel: metric bolt mechanical property grade can be divided into: 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 13.51, bolt material nominal tensile strength of 800MPa The first 8)
2, the yield ratio of bolt material is 0.8 The second 8 is 0.8)
3. The nominal yield strength of bolt material is 800 × 3. The relationship between shear stress and tensile force has been proved by experiments. For general steel, the relationship between allowable shear stress and allowable tensile stress is as follows: plastic material [t] = 0.6-0.8 [b]; Brittle material [t] = 0.8-1.0 [b]
part stress value
the maximum stress value of parts or components in mechanical design or engineering structure design. In order to determine whether the working stress of a part or component is too high or too low after loading, it is necessary to determine a measurement standard in advance, which is the allowable stress. When the working stress of a part or component does not exceed the allowable stress, the part or component is safe in operation, otherwise it is unsafe. Allowable stress is the basic data in mechanical design and engineering structure design. In practical application, the allowable stress value is generally stipulated by the national engineering department according to the principles of safety and economy, material strength, load, environmental conditions, processing quality, calculation accuracy and the importance of parts or components. The allowable stress is equal to the failure stress (yield limit or strength limit in static strength design and fatigue limit in fatigue strength design) of the material after considering various influencing factors, divided by the safety factor. Plastic materials (most structural steels and aluminum alloys) are based on the yield limit, divided by the safety factor to obtain the allowable stress, i.e[ σ]=σ s/nn=1.5~2.5; For brittle materials (cast iron and high strength steel), the allowable stress is obtained by dividing the strength limit by the safety factor, i.e[ σ]=σ b/n(n=2~5)( N is the safety factor)
plastic material [t] = 0.6-0.8 [b]
; Brittle materials [t] = 0.8-1.0 [b]
.
performance grade, material and heat treatment chemical composition, %Tempering temperature
℃
min
C P
Max s
Max B1)
Max
min max
3.62) carbon steel-0.20 0.05 0.06 0.003 -
4.62) - 0.55 0.05 0.06 0.003 -
4.82)
5.6 0.13 0.55 0.05 0.06 0.003 -
5.82) - 0.55 0.05 0.06
6.82)
8.83) low carbon alloy steel (such as boron, manganese or chromium), Quenching and tempering or medium carbon steel, quenching and tempering 0.154) 0.04 0.035 0.035 0.003 425
0.25 0.55 0.035 0.035 0.035
9.8 low carbon alloy steel (such as boron, manganese or chromium), quenching and tempering or medium carbon steel, quenching and tempering 0.154) 0.35 0.035 0.035 0.003 425
0.25 0.55 0.035 0.035 0.035
10.95), 6 low carbon alloy steel (such as boron, manganese or chromium), 0.35 0.035 0.035 0.003 340
10.96) medium carbon steel, Quenched and tempered or low and medium carbon alloy steel (such as boron, manganese or chromium), Quenched and tempered or alloy steel quenched and tempered 7) 0.25
0.204) 0.55
0.55 0.035
0.035 0.035
0.035 0.03425
0.20 0.55 0.035 0.035 0.035 0.003
10.96), 8) and 9) alloy steel, Quenching and tempering 7) 0.280.50 0.0350.0350.003 380
1) the content of boron can reach 0.005%, and its non effective boron can be controlled by adding titanium and / or aluminum
2) the maximum content of sulfur, phosphorus and lead is 0.34% of sulfur; 11% for phosphorus; 35% lead
3) in order to ensure good hardenability, the fastener with thread diameter more than 20 mm should be made of grade 10.9 steel
4) the lowest manganese content of low carbon alloy steel with carbon content less than 0.25% (barrel sample analysis): 8.8 grade: 0.6%; Grade 9.8, 10.9 and 10.9: 0.7%
5) a horizontal mark should be added under the performance grade code of the proct. Grade 10.9 should meet all the performance requirements of grade 10.9, and the lower down fire temperature will cause different degrees of stress weakening under the condition of raising temperature
6) the material used for this performance grade should have good hardenability to ensure that about 90% martensite structure can be obtained in the core of fastener thread section after quenching and before tempering
7) alloy steel should contain at least one of the following elements, the minimum content of which is 0.30% chromium; 30% nickel; 20% molybdenum; 10%
8)< The chemical composition and tempering temperature are still under investigation.
the pressure feed of the connected parts also needs to be inspected, and the pressure feed force = pressure feed strength * aperture * plate thickness.