Analytical, FEA and Experimental Methods for Computing the Resilience of Tapped Thread Joints

Abstract

Bolted joint behavior is based on many parameters, many of which are not well known or understood. The basic parameters describing the signature behavior of the bolted joint are the fastener and clamped joint flanges’ resilience. The level of confidence in the resilience parameter defines the confidence level of further analysis performed throughout the design phase. For general cases with simple configurations of the bolt and joint members, well-known analytical methods such as VDI 2230 satisfy the purpose of bolted joint analyses. However, in practice there are cases which deviate from the idealized joint, such as complex bolted joint geometry or dissimilar materials which cannot be simplified for an analytical model. The particular case studied here is that of a screw joint or tapped thread joint (TTJ) where the analytical model is ambiguous. In addition, for TTJs that are critical to safety a high confidence in the result is desired, so finite element analysis (FEA) or experimental methods are preferred to assess the resilience of the clamped and tapped flanges. This paper presents FEA modeling as well as analytical methods for complex joints, particularly for TTJ configurations. Resilience values for FEA and analytical approaches are presented, as well as experimental results for validation.