MechanicalEngineer20
Mechanical
- Mar 1, 2012
- 3
The company I work for uses NG-3232.1, to qualify fasteners. I have a question concerning primary and secondary bolt stresses. I am having a hard time grasping the understanding of a primary and secondary stress and wanted to make sure that my understanding of the topic so far is correct.
Pm is the primary membrane stress, which is only the preload applied to the bolt via torque. Only thermal expansion would lessen the preload, hence the tight join check for 3232.1e against external loads.
So for Pm primary stress, there will always only be the preload and thermal expansion forces??
Then the Pb would be any primary bending stresses due to the initial preload?
Then my second part of the question is for Qm and Qb the secondary stresses. A secondary stress will only be evaluated if it is a limiting stress correct? In other words, if an external force is not limiting, it is not considered to be a secondary stress when evaluating the fastener. Also, I was wondering if anyone could provide a few examples of a limiting stress.
Thank you for your help everyone.
Pm is the primary membrane stress, which is only the preload applied to the bolt via torque. Only thermal expansion would lessen the preload, hence the tight join check for 3232.1e against external loads.
So for Pm primary stress, there will always only be the preload and thermal expansion forces??
Then the Pb would be any primary bending stresses due to the initial preload?
Then my second part of the question is for Qm and Qb the secondary stresses. A secondary stress will only be evaluated if it is a limiting stress correct? In other words, if an external force is not limiting, it is not considered to be a secondary stress when evaluating the fastener. Also, I was wondering if anyone could provide a few examples of a limiting stress.
Thank you for your help everyone.
