[Technical Information] How to grasp loosening? Axial repeated load test

We will introduce the testing method and examples of axial repeated load tests in detail using photographs!

In addition to the perpendicular direction of the bolt axis, axial repeated loads can also cause loosening. In the case of axial repeated loads, if the bolt and nut are properly tightened and sufficient initial axial force is applied, it can be understood that even with a large repeated load of 80% of the bolt yield axial force Fy, common hex nuts are unlikely to experience rotational loosening. On the other hand, if the initial axial force significantly decreases due to some factor, hex nuts and hex nuts with spring washers will completely experience rotational loosening at 50% of the bolt yield axial force Fy, and even double nuts will see the initial axial force drop to about half. From the above results, it can be understood that in the case of hard lock nuts, even when the initial axial force is low or decreases due to some factor, they are less likely to experience rotational loosening. *For more details, please refer to the PDF document or feel free to contact us.

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