Calculation of shear force

1.

Shear force F (n) = sectional area s (mm 2) x yield strength σ "Shear" is a relative dislocation deformation phenomenon of the cross section of the material under the action of a pair of lateral external forces (that is, the force perpendicular to the action surface) which are very close, the same size and opposite to each other. The force that can make the material proce shear deformation is called shear force or shear force

extended data:

the key to judge whether "shear" or not is whether the cross section of material has relative dislocation. Therefore, cutting vegetables with a kitchen knife is not a shearing phenomenon (because there is no relative dislocation in the cross section of vegetables), while cutting nails with scissors is a shearing phenomenon (relative dislocation in the cross section of nails). Note: using nail clippers to cut nails is not a cutting phenomenon, although it can also cut nails off. It belongs to extrusion deformation

As for the source of "shear force", it is of course caused by pressure. It can also be said that shear force is a special form of pressure

2.

Calculation of shear stress: in practical calculation, it is assumed that the shear stress is uniformly distributed on the shear plane. If a is used to represent the shear plane area, the stress is

V -- the shear force acting along the web plane in the calculation plane

s -- calculate the area moment (static moment) of the section above or below the shear stress to the neutral axis

I -- Section moment of inertia

T -- web thickness

reference source: Network shear stress

reference source: Network shear stress

3.

Shear stress formula σ= WS / a (kg / mm2)

shear stress refers to the internal force generated by the interaction between various parts of the object when the object is deformed e to external factors (stress, humidity change, etc.), so as to resist the effect of this external factor, and try to make the object recover from the position after deformation to the position before deformation

< H2 > extended data

when an object is deformed e to external factors (stress, humidity change, etc.), the internal force of interaction between various parts of the object is generated to resist the effect of this external factor, and the object is tried to recover from the position after deformation to the position before deformation. The internal force per unit area at a point of the section under investigation is called stress. What is tangent to the same section is called shear stress or shear stress

the so-called shear force is: two parallel forces acting on the same object are very close (but not zero), equal in size and opposite in direction. For example, when scissors cut an object, the force on the object is shear force. Or the internal force of an object e to its physical properties in order to recover the deformation caused by torque

4. The shear force divided by the cross-sectional area is the stress. There is a difference between stress and stress. The former is the set degree, the latter is the size. The shear force is generally known. The shear force is generally caused by tension or pressure. For example, it is common in bolts or steel plates

5.

Formula: shear force F (n) = sectional area s (mm 2) x yield strength σ (PA); It has nothing to do with material

take round steel with diameter of 160 as an example:

shear strength = 0.6-0.8 tensile strength (51.6kg/mm for high quality steel); The calculated s = 200.96mm

maximum shear force = 0.8x51.6x200.96 = 8295.3kgf; Minimum shear force = 0.6x51.6x200.96 = 6221.7kgf

The round steel can be divided into hot rolling, forging and cold drawing. The specification of hot rolled round steel is 5.5-250mm. Among them: 5.5-25 mm small round steel is mostly supplied in bundles of straight bars, which are commonly used as reinforcement, bolts and various mechanical parts; Round steel larger than 25 mm is mainly used for manufacturing mechanical parts, seamless steel tube billets, etc

extended data:

the resultant force of the external forces acting on the two sides of the member is a pair of transverse concentrated forces with the same size, opposite direction and very close action lines

under the action of such external force, the deformation characteristics of the component are: Taking the cross section between the two forces as the dividing line, the two parts of the component move relatively along the plane. This form of deformation is called shear, and its section is shear plane. The shear force per unit area of a section is called shear stress

calculation of shear stress: in practical calculation, it is assumed that the shear stress is uniformly distributed on the shear plane. If a is the shear plane area, the stress is τ= F/A; τ It is tangent to the shear plane, so it is called shear stress

τ- Shear stress MPa; F - shear force N; A-shear area is not related to material, but shear resistance is related to material

6. F = kltj
k: safety factor, l: shear length, t: material thickness, j: material shear strength. K is generally taken as 1.3

7. If the shear line without angle is relatively cheap, it can be generally hob type. The speed should be 1 m step speed (0.4 ~ 1.0 mm thickness): 70 pieces / min (the highest speed of the equipment), and the stacking should be alternate front and back 2 stacking stations (a total of 4 stacking stations, which can continuously proce on-line)
the factory and warehouse should be related to your preparation costs. There is a big difference between the costs of external logistics and self purchase. Sheet warehouse depends on your logistics operation and proction plan. If the above two problems can be solved, 5000 square meters is enough.

8.

Shear force of bolt = shear strength of bolt * effective cross-sectional area of bolt (shear on one side, shear on both sides * 2)

the pressure feed of the connected part 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 the 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, 20 manganese titanium boron steel. Common bolts are usually made of Q235 steel. From the strength level: high strength bolts are widely used

extended data

classification

1. According to the stress mode of connection, it can be divided into ordinary and reamed. According to the head shape: hexagonal head, round head, square head, countersunk head and so on. The hexagonal head is the most commonly used. Generally, countersunk head is used where connection is required

2. The English name of riding bolt is U-bolt, which is a non-standard part with U shape, so it is also called U-bolt. There are threads at both ends, which can be combined with nuts. It is mainly used to fix tubular objects such as water pipes or flakes, such as leaf springs of cars. Because its way of fixing objects is like riding on a horse, it is called riding bolt. According to the thread length, it can be divided into full thread and non full thread

According to the thread type, it can be divided into two types: coarse tooth and fine tooth. According to the performance grade, bolts are divided into 8 grades: 3.6, 4.8, 5.6, 5.8, 8.8, 9.8, 10.9 and 12.9. Bolts above grade 8.8 (including grade 8.8) are made of low carbon alloy steel or medium carbon steel and heat treated (quenching and tempering), which are generally called high strength bolts, while bolts below grade 8.8 (excluding grade 8.8) are generally called ordinary bolts

According to the manufacturing accuracy, ordinary bolts can be divided into three grades: A, B and C. grade A and B are refined bolts and grade C is rough bolts. For connecting bolts used in steel structure, unless otherwise specified, they are generally common rough C-grade bolts

(1) the bolt rod of Grade A and B bolts is machined by lathe, with smooth surface and accurate size. Its material performance grade is grade 8.8, with complex fabrication and installation, high price and few use

(2) grade C bolt is made of raw round steel, and its size is not accurate enough. Its material property grade is grade 4.6 or 4.8. Shear connection has large deformation, but it is easy to install and has low proction cost. It is mostly used for tensile connection or temporary fixation ring installation

stress mode

common and reamed. Ordinary bearing mainly axial force, can also bear the requirements of the lateral force is not high. The bolt used for reaming should match the size of the hole and be used when subjected to transverse force

9. Shear stress formula σ= WS / a (kg / mm2)
calculation formula
1. Average shear stress
V -- shear force on calculation section
A -- calculated cross-sectional area
B -- section width; H-section height
peak stress
2. Shear force calculation formula based on shear flow
v-shear force acting along the web plane
s -- calculate the area moment (static moment) of the section above or below the shear stress to the neutral axis
I -- Section moment of inertia
T -- web thickness
extended data:
shear stress refers to the internal force generated by the interaction between various parts of an object when the object is deformed e to external factors (stress, humidity change, etc.), so as to resist the effect of this external factor, and try to make the object return to the position before deformation from the position after deformation< 1. Natural aging is a method to stabilize the dimensional accuracy of parts by exposing them to the outside for several months to several years. A large number of experiments and proction practice have proved that natural aging has a good effect of stabilizing the dimensional accuracy of castings< However, the change of resial stress is not obvious after natural aging. It can be seen from Figure 3-1 that the resial stress of the casting sample only decreases by 2-10% after one year; The results show that the maximum resial stress is reced from 80N / mm to 70N / mm, and the average resial stress is reced from 38n / mm to 30n / mm,
that is, it is only reced by about 10-20%. It can be seen that considerable resial stress still exists in the castings which have stopped deformation after natural aging. For those castings which need to bear a large load in service, the service performance of castings may be affected when the service stress is superimposed on the higher resial stress. Therefore, it must be carefully considered whether this aging method should be adopted
2. According to the hot time method, put the workpiece into the heat aging furnace for heat treatment, and slowly relieve the stress. The disadvantages of this method are also very obvious. For example, aluminum alloy workpieces with very strict temperature control requirements in satellite manufacturers and giant workpieces as long as 10 meters or more cannot be processed by this method
and this method also brings a lot of pollution and energy consumption. With the further requirements of environmental protection in China and the world, the treatment method of thermal aging furnace is facing the situation of full withdrawal
source of reference: network stress
source of reference: network shear stress