In the recent Race Engine Technology magazine article on the subject of fasteners, Wayne Ward touched on the subject of locking nuts and locking thread inserts. There are a great many applications where the loss of a fastener is not critical to the operation of the system as a whole; indeed it is common to build in a certain level of redundancy into a bolted or riveted joint for loss or failure of fasteners and the accompanying loss of pre-load. Again, even in this situation, the physical...
After having calculated bolt stiffness, or measured the load-deflection curve directly, the best way to calculate pre-load is to measure the extension of the bolt directly. This method is preferred for con rod bolts and all con rod and bolt suppliers generally recommend this method. The fasteners require design features to allow measurement with a special micrometer. This method is impossible for fasteners in blind holes. For large fasteners in blind holes the extension can be measured...
In previous articles we have looked at how to calculate fastener and joint stiffness, and seen how these values of stiffness can affect the proportion of the working load experienced by the fastener by calculating the ‘load coefficient’.See https://www.highpowermedia.com/articles/401/back-to-basics-part-2/ The forthcoming article in Race Engine Technology on the subject presents some simple examples of how variations in fastener stiffness can affect the levels of stress in...
Last month, we looked at some basic calculations regarding cyclic loading of fasteners. We must apologise for the recurring errors in printing symbols. The questions marks last month should have been ‘delta’ symbols. For example strain was given as: e = ?L/L This month we shall look at the calculation of joint stiffness, and the good news is that the methods and the basic calculations are the same. The combination of stiffness of different members is dealt with in exactly the...
Last month, we looked at some basic calculations regarding cyclic loading of fasteners. Engine design engineers need a good understanding of the subject in order to correctly design the optimised fasteners required, but also those whose business is in improving the performance of engines need to be able to calculate when the standard equipment just isn’t going to be good enough. We examined the concept of load coefficients and looked at a very simple example of how the load...