Influence of load on stress intensity factor at crack front of heavy duty gear
The gear pair model with semicircular initial crack is established. The mode 1 stress intensity factor is calculated when the […]
The gear pair model with semicircular initial crack is established. The mode 1 stress intensity factor is calculated when the […]
The figure is a graph of the leading edge mode I stress intensity factor of a semicircular crack with a
Through the bending fatigue test and corresponding numerical simulation, it is obtained that the fracture of the tooth root is
After setting the corresponding analysis conditions, enter the solution analysis stage. After the calculation, you can get the Mises equivalent
Cracks will first appear at the tooth root of the gear, because when the gear is running, the meshing other
Von Mises proposed for material conditions under complex stress: The shape change energy density is: Therefore, Mises yield condition is:
The model used for numerical simulation of fatigue crack growth is the same as the compact tensile specimen of 42CrMo
By referring to the national standard GB / t6398-2000 test method for fatigue crack growth rate of metallic materials, the
The experimental measurement shows that the lower threshold of fatigue crack growth is 15.29 and 5.08 when the stress ratio
As can be seen from the figure, when the stress ratio r = 0.1 and the fatigue crack length α
Elber proposed the concept of crack closure, and used the theory of crack closure to explain the fatigue crack growth
Heavy duty gear is the core component of large equipment transmission. It is widely used in mining, metallurgy, building materials,
Taking low-speed and heavy-duty gear as the research object, the fatigue crack propagation and fatigue fracture of gear teeth are
Before carrying out the bending fatigue test, it is necessary to determine the stress level of the test. Two of
Fatigue cracks often occur when the component is under the condition of alternating load for a long time. The initial
The fatigue crack growth mechanism of 42CrMo steel was studied by fatigue crack growth test. The law of fatigue crack
Figure 1 is the contact pressure diagram of the gear in the process of meshing, and the pressure distribution of
Fatigue fracture is the surface formed by the fatigue fracture of the test sample or component during the test or
The results of the overall equivalent stress of the gear are shown in Figure 1. The variation law of dynamic
The macro morphology of fatigue fracture of low speed and heavy load gear teeth can be divided into three obvious
With the continuous improvement and innovation of fatigue crack testing methods, the research on small fatigue cracks has gradually changed
Wu Zhenpeng and others took the helical gear as the research object, modeled the helical gear, simulated the crack propagation
Since the test data under each stress level obey the lognormal distribution, when the normal probability density function is known,
Robert Basan proposed the mathematical model of slip line contact and the calculation model of multiaxial fatigue life based on
The number of fatigue cycles under four stress levels is counted in the order from small to large, and the
Although the strength of mechanical gear bearing capacity does not entirely depend on gear hardness, improving gear hardness is still
Before calculating the tooth root stress of the gear, it is necessary to find the exact position of the load
Because the mechanical operation is mostly heavy load, medium and low speed transmission, most of them start frequently and often
Before carrying out bending fatigue strength, the primary task is the design and manufacture of gear specimens. Because the object
Comparison of machinability and forgeability between Ni Cr and Ni Cr Mo steels The machinability of different materials is mainly
In order to study the problem of fatigue crack propagation and fatigue life of low-speed and heavy-duty gear, a low-speed
For the statistical analysis of this section, the relevant data of stress ratio r = 0.6 is also used. The
Other countries in the world mainly use Cr Ni and Cr Ni Mo carbon steel. Compared with Mn Cr steel
In order to verify the accuracy of the fatigue crack growth test of the compact tensile specimen, the data of
Gear is a kind of mechanical element with continuous meshing transmission of motion and power on the rim, which plays
The theoretical Mises stress nephogram distribution law of the numerical simulation model of compact tensile specimen under macro state is
Although the deep carburizing of large heavy duty gears improves the bearing capacity and prolongs the service life, it still
Tooth wear is one of the main failure forms of low speed and heavy load gear transmission. H. Winter has
The model used for numerical simulation of fatigue crack growth is the same as that of 42CrMo steel compact tensile
The important parameters to ensure the load-bearing capacity of low-speed and heavy-duty hard face gear are: enough central strength and
With the continuous progress of the test, under the action of cyclic load, cracks appear on the sample and continue
The deep carburizing of large heavy duty gears has a history of more than 10 years in foreign countries, with
The fatigue crack growth rate DA / D N and the stress intensity factor at the crack tip under different
It is very important to choose the hardening heat treatment method of low speed and heavy load gear reasonably. The
The data of crack tip stress intensity factor (SIF) and crack length under different stress ratios collected through the test
The main damage form of gear in soft tooth surface rolling mill is severe plastic deformation of gear surface, which
Using normalizing big gear and quenching and tempering small gear, the tooth surface after use can be extruded into mirror
The fatigue crack growth test of compact tensile specimen was carried out according to the national standard GB / T
As the cement mill, mine hoist and other soft tooth surface reducer gear, the main problem is to eliminate early
The fatigue crack growth test was carried out in the State Key Laboratory of new metal materials, University of science
When gears work, they bear two kinds of stress, so there are few two kinds of failure. One is that
42CrMo steel is a kind of ultra-high strength steel, which has strong resistance to plastic deformation, less possibility of brittle
There are three ways to improve the bearing capacity of gears, namely, ① improving the structure of reducer, such as
The existence of the worst speed in the boundary lubricated gears has not been discussed in the literature. There is
It is known from the test results that for the low-speed and heavy-duty lubricated gears with circumferential velocity v =
The tests were carried out on the modified CL-100 gear testing machine. The schematic diagram of the testing machine is
The carburizing layer of large low-speed and heavy-duty gears is deep, and the surface carbon concentration is low. The carburizing
1.Technical Requirements 20grni2moa steel material, module M = 6, number of teeth z = 38, width of teeth H =
The low-speed and heavy-duty gear assembly established by SolidWorks is exported to. Step format and imported into ANSYS Workbench. The
The accurate modeling of gear is an important basis for analyzing the contact stress and crack propagation law of gear.