LOADABILITY OF BOLT-NUT ASSEMBLIES - DETERMINATION OF CRITICAL NUT HEIGHT BY STAIRCASE METHOD

In the International Standards ISO 898-2 and ISO 898-6, the mechanical properties are specified for various styles and property classes of n uts. The specified values in these International Standards are calcula ted based on the ''Alexander Theory'', in which the minimum nut height and the proof load are determined so as to central the failure modes of a bolt-nut assembly. In this study, an experimental investigation u sing the staircase method is performed to verify the Alexander Theory. The experimental results show that the failure mode of a bolt-nut ass embly can be predicted accurately by the Alexander Theory. It is also pointed out that there are some disagreements in the values of stress under proof load between calculation and the specification of ISO 898- 6.