Abstract:

ESDU 67034 gives a method of estimating the effect of an inclined nut seating on the fatigue strength of a steel screw thread. The method is based on the calculation of an equivalent stress cycle which would produce the same endurance if the screw thread were loaded axially. The form of the relation between equivalent and nominal stresses is derived from a simplified elastic theory. Two sets of curves are presented, corresponding with estimates of the 'best' and 'worst' conditions likely to obtain in practice. The experimental results show that the actual behaviour of the type of connection considered here is much more complex than has been assumed in the analysis. For this reason the method may be regarded only as a guide to what may occur in practice.