howkers
Mechanical
- Nov 4, 2003
- 29
A colleague in Sweden is in the process of designing a new flange joint bolted together with bolts (M30 to M100). Current calculation methods within the department are 10+ years old and are limited to typically 45% of the yield stress of the bolt shank, this limitation is due to the stripping of the female threads within the flange (blind tapped holes used as opposed to nuts).
The method in use is a crude approximation based on just a proportion of the thread shear area and material yield stress. It is known (and has been completed for certain customer orders) that the threads can take a preload equivalent up to 70% of the bolt yield without any problems, but simple methods to prove this are not known.
Does anyone have any experience with bolting technology and knows of a method that models the female thread strength to a greater accuracy and thus will allow a greater utilisation of the bolt preload? Any help or references would be greatly appreciated.
The method in use is a crude approximation based on just a proportion of the thread shear area and material yield stress. It is known (and has been completed for certain customer orders) that the threads can take a preload equivalent up to 70% of the bolt yield without any problems, but simple methods to prove this are not known.
Does anyone have any experience with bolting technology and knows of a method that models the female thread strength to a greater accuracy and thus will allow a greater utilisation of the bolt preload? Any help or references would be greatly appreciated.
