Failure analysis of thin-walled gear used for mechanical transmission mechanism of airlock in nuclear power plant

According to the failure mechanism analysis of thin-walled gear, the gear material is 40Mn2. In the process of gear meshing, the stress far away from the meshing part is far less than that of the meshing part. Simplify the whole gear meshing transmission, omit other teeth, and only establish the calculation model for four adjacent teeth. In the process of gear meshing, the stress in the thickness direction is ignored, and the stress level in other parts is relatively low except the contact part and root of gear. The three-dimensional solid is simplified to two-dimensional plane strain problem.

By adjusting the relative positions of the two gears, the teeth are kept in contact and the contact unit is established at the contact position. The gear entity unit type is plane82, and the contact unit pair is 170 and 169. The total number of cells is 10595 and the total number of nodes is 32243. The input torque load is 720 n · m, which is applied to the center of thin-walled gear.

After the boundary conditions are set, the input torque load is applied to the center of the gear and the load is calculated. According to the calculation results, the maximum stress intensity of the thin-walled gear is distributed at the root after the local contact stress concentration is eliminated. Through further setting the stress assessment path at the root of the tooth and stress linearization, the maximum stress assessment results under different paths are obtained.

On whether it is membrane stress or membrane stress + bending stress, the stress ratio is greater than 1, the calculated value is greater than the allowable limit value of the material, and the calculation fails. The calculation results further verify the unreasonable structure design and material selection of thin-walled gear used in the mechanical transmission mechanism of airlock door.

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