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Bench test method for automobile axle shaft
1 Subject content and application scope
This standard specifies the device and instruments, test procedures, as well as test result calculation and evaluation for the static torsional strength and torsional fatigue life tests of automobile axle shaft.
This standard is applicable to full-floating axle shafts and semi-floating axle shafts of various automobiles with non-steering axle having a maximum axle load mass of 13t or less than 13t.
2 Terms and symbols
2.1 The symbols used in this standard are shown in Table 1.
Table 1
S.N Symbol Term Unit
2.1.1 Me max Maximum torque of engine N·m
2.1.2 G2 Full load of rear drive axle kg
2.1.3 G1 Full load of front drive axle kg
2.1.4 ik Gear ratio of transmission first gear
2.1.5 io Final ratio of drive axle
2.1.6 ip Low gear ratio of transfer case
2.1.7 rk Rolling radius of tire m
2.1.8 φ Road adhesion coefficient φ=0.8
2.1.9 n Number of drive axle when using transfer case
2.1.10 Mj Calculating torque of axle shaft test N·m
2.1.11 M Maximum yield torque or torque of axle shaft at fracture N·m
2.1.12 θ Angular displacement at static torsion of axle shaft (°)
2.1.13 B Wheel track m
2.1.14 L Cantilever length of semi-floating axle shaft m
2.1.15 Mt Torque of semi-floating axle shaft N·m
2.1.16 Mb Bending moment of semi-floating axle shaft N·m
2.1.17 Mth Equivalent torque on semi-floating axle shaft N·m
2.1.18 K Static torsional strength safety factor of axle shaft
2.1.19 Mmax Maximum torque for fatigue life test of axle shaft N·m
2.1.20 Mmin Minimum torque for fatigue life test of axle shaft N·m
2.1.21 Ma Alternating torque amplitude for axle shaft life test N·m
2.1.22 Mm Average torque for axle shaft life test N·m
2.2 Ultimate torque of axle shaft static torsion M
It refers to the torque of axle shaft at fracture or the maximum yield torque.
2.3 Ultimate life of axle shaft torsion fatigue test
The life of axle shaft till the change in dynamic angular displacement is equal to or greater than 10% of the dynamic angular displacement when a crack occurs on the surface of the axle shaft, which is defined as the ultimate life of this axle shaft.
3 Axle shaft static torsional strength test
3.1 Test sample
a) Test samples must comply with the requirements in design drawings;
b) Three test samples attached with design drawings, technical parameters and process data are required;
c) The test sample must be randomly selected from no less than 200 samples.
3.2 Test method
3.2.1 Test device and instruments
a) Torque tester;
b) Function recorder;
c) Dynamic resistance strain gauge;
d) Angular displacement sensor;
e) Torque sensor.
The overall test precision shall be less than or equal to 2%.
3.2.2 Test procedures
a) Connect one end of the axle shaft to the output end of the torque tester, and connect the other end to the fixed bracket;
b) During installation, it shall be ensured that the axle shaft is coaxial with the torque tester, so that the axle shaft is not subject to additional bending moment and torque;
c) Start the torque tester and slowly and continuously apply load till the fracture of axle shaft. Record and plot torque - angle curve.
3.3 Data processing
3.3.1 Static torsional strength safety factor K of axle shaft:
(1)
Figure 1 Torque - angle curve of axle shaft at fracture
Figure 2 Torque - angle curve of axle shaft at yield
3.3.2 Determination of calculating torque Mi
The smaller one between the value calculated based on the maximum torque of the engine and that based on the maximum adhesion force is taken.
3.3.2.1 Full-floating axle shaft
a) When calculated based on the maximum torque of the engine
Mj=0.6·Me max·ik·io (2)
b) When calculated based on the maximum adhesion force
(3)
3.3.2.2 Off-road automobile axle shaft
a) When calculated based on the maximum torque of the engine
1 Subject content and application scope
2 Terms and symbols
3 Axle shaft static torsional strength test
4 Axle shaft torsional fatigue life test
Annex A (Supplementary) Axle shaft torsional fatigue life test record form
Additional explanation
