3 Drive axle stress conditions and stress distribution

The diagram of the force diagram of the drive axle and the bending moment diagram are shown in Figure 3.

It is seen from the force diagram that the synthetic stress is gradually increased from the center of the tire to the joint between the mount and the frame. Therefore, according to its force characteristics, the modulus of the cross section of the axle housing is also required to increase.

In the first scheme (Fig. 2a), the left and right sides of the weld are circular cross-sections, with the left side being the A-A section and the right side being the B-B section.

Section modulus W=(π(D4-d4))/32D, due to diameter D1=D2, d1 WB, synthetic stress δ = M / W, WA ≈ WB on the left and right sides of the weld, so δA < δB.

From the bending moment diagram of Fig. 3, the synthetic stress δA < δB can also be seen.

It can be seen that the section modulus decreases with the gradual increase of the synthetic stress, and the change of the cross-sectional area does not match the force change of the axle housing and the synthetic stress. One of the weak points of the strength load, that is, the dangerous section is the cross section of the axle shell B. According to the specific data of the ZL50C loader, according to the maximum water boosting force of the loader, after the bucket is blocked, the rear wheel leaves the ground, and the combined stress of the dangerous section B section of the drive axle is calculated as: δA=182N/ Mm2.

In the fourth scheme (Fig. 2d), the left side of the weld is a circular cross section, and the left side is A-A cross section, the diameter D1, d1, and the section modulus W=(Ï€(D4-d4))/32D.

The right side of the weld is gradually transformed into an elliptical cross section, and the elliptical ring section is gradually enlarged in radial shape. The right side is B-B section, and the ring section is compared with the left side, because the diameter D1= D2, d1 WB, synthetic stress δ = M / W, WA ≈ WB on the left and right sides of the weld, so δA < δB.

The resultant stress δA < δB can also be seen from the bending moment diagram of Fig. 3.

It can be seen that the change of the cross-sectional area and the change of the force of the axle shell and the progressive increase of the synthetic stress, the change of the cross-sectional area is consistent with the force change of the axle shell and the characteristics of the synthetic stress. The weak link of the strength load is consistent with the force variation of the axle housing and the synthetic stress characteristics. The weak link of the strength load is moved from the axle housing to the section A-A of the forging support shaft. The composite stress of the support A-A section is δA=169.62N/mm2 calculated by the same working conditions and the same data above.

Compared with the first scheme, it is also a dangerous section and its composite stress is small, so the safety factor is large.

In summary, the comparison between the two schemes, the structural design of the fourth scheme conforms to the force characteristics of the axle, and the cross-sectional area increases with the gradual increase of the synthetic stress, and the diameter of the left and right sides of the weld is larger than that of the first scheme. The diameter is large, the strength will be correspondingly high, and the safety factor is high, so the fourth scheme is the preferred scheme.

Author: Zhengzhou engineering machinery factory Zhengzhou University Guorui Qin Su Xiumei Liu Shuangxia

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