Calculation of thread length installed in assemblies of threaded aluminum parts (#1019)

Authors

Martínez Martínez, Manuel

Hernández Pérez, Pedro Francisco

Abstract

In this article we present an equation for the calculation of the length of threading between a bolt and a tapped part. We approach the problem where both parts have different mechanical resistances. The equation allows us to calculate the length of the thread necessary to prevent any of the three types of failure that could appear: stripping of the part thread, stripping of the thread of the bolt or rupture of the bolt. This allows us to have more different combinations of assembly materials from the point of view of its resistance and the prevention of static failure given that there was no method to approach these cases. The equation can be applied to threaded aluminum assemblies since this is one of the materials used in the development process. The process of development consists of an axisymmetric finite element model and a criterion of rupture by damage due to located plastic deformation. This model allows us to analyze the parameters involved in the design up to conditions of failure. These parameters include characteristics of the materials and dimensions of the assembly. Also, the process of development involves a model of experiments design to determine in the given equation, the behavior of the effects in the different types of failure. Finally, the results obtained from the equation are presented and compared against the results of physical tests in laboratory proving to be very close and satisfactory.