- The Vons Mises stress distribution of the seal at different medium pressures. It can be seen from the results that as the medium pressure continues to increase, the seal part is squeezed into the gap, and the maximum stress also moves from the middle area to the right, and finally at the corner. When the maximum value is reached, the contact part between the seal and the corner of the seal groove is often the part where the O-ring seal is damaged by shearing.
- Therefore, when the working pressure of the medium is high, it is necessary to choose a material with higher hardness or place a retaining ring on the low pressure side of the seal to prevent the seal from being squeezed out, prolong the life of the seal, and reduce the possibility of seal failure.
- When the O-ring is assembled with interference, it squeezes with the upper and lower flanges, resulting in radial compression displacement, and there is contact stress on the contact surface. When the contact stress exceeds the medium pressure, it will prevent the fluid from flowing to the other side, thereby Sealing is achieved.
- Therefore, the size of the contact stress reflects the sealing ability of the seal, and the necessary condition to ensure the effective sealing of the seal is that the maximum contact pressure on the sealing interface is greater than or equal to the medium pressure.
- From the contact stress distribution curves of the contact surface between the upper flange and the O-ring under different pre-compression ratios, it can be seen that the contact stress on the contact surface exhibits a parabolic distribution, and the contact stress reaches the maximum value at the midpoint of the contact length , and then the stress gradually decreases from the peak point to both sides. The distribution law of these famous Hertz contact curves is similar, with the increase of the pre-compression of the seal, the contact stress and contact length increase continuously.
- In the curve of the maximum contact stress under different pre-compression, it can be seen that the maximum contact stress on the contact surface increases approximately linearly with the increase of the pre-compression rate of the seal, but too large a compression rate will make the seal It is beneficial to enhance the sealing effect, but too large a compression rate will cause a large residual deformation of the seal, resulting in stress relaxation, resulting in leakage.
- Therefore, under the condition of ensuring effective sealing, an appropriate amount of pre-compression should be selected as far as possible to ensure the service life of the seal.