Publications Details

Multiaxial loading of threaded fasteners

Camarena, Ernesto; Quintana, Anthony; Yim, Victoria; Grimmer, Peter; Mersch, John; Smith, Jeff; Emery, John; Castelluccio, Gustavo

The simulation of various structural systems often requires accounting for the fasteners holding the distinct parts together. When fasteners are not expected to yield, simple reduced representations like linear springs can be used. However, in analyses of abnormal environments where fastener failure must be accounted for, fasteners are often represented with more detail. One common approach is to mesh the head and the shank of the fastener as smooth cylinders, neglecting the threads (referred to as a plug model). The plug can elicit a nonlinear mechanical response by using an elastic-plastic material model, which can be calibrated to experimental load-displacement curves, typically in pure tension. Fasteners rarely fail exclusively in pure tension, so the study presented here considers current plug modeling practice at multiaxial loadings. Comparisons of this plug model are made to experimental data as well as a higher fidelity model that includes the threads of the fastener. For both models, a multilinear elastic-plastic constitutive model is used, and two different failure models are explored to capture the ultimate failure of the fastener. The load-displacement curves of all three sets of data (the plug model, threaded model, and the experiments) are compared. The comparisons between simulations and experiments contribute to understanding the role of multiaxial loading on fastener response, and motivate future work on improving fastener models that can accurately capture multiaxial failure.