PSI - Issue 12

Valerio G. Belardi et al. / Procedia Structural Integrity 12 (2018) 281–295 V.G. Belardi et al. / Structural Integrity Procedia 00 (2018) 000–000

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of the theoretical model having α 1 + α 2 angular extension with high degree of fidelity. The composite bolted joint element presents a very limited amount of DOFs, if compared to complex 3D models or even to shell models, and it is capable of improving the results accuracy with respect to approximate simulation techniques.

Fig. 3: Composite bolted joint element.

The sti ff ness equivalence between the theoretical reference model and the novel composite bolted joint element is obtained through the solution of a system of linear equations that is needed to determine the geometrical properties of the radial beams that must assure the structural equivalence which is established adjusting the beam cross-section properties in terms of inertia moment J y and area A . Consequently, the sti ff nesses equivalence is obtained through the solution of the following system of algebraic equations that poses the equalities between the theoretical sti ff ness terms, defined as the ratio of a resulting generic force at the peripheral node and the displacement evaluated at the axis of the rigid nugget, and those related to the beam elements:   K th Fn u = K beam Fn u J y K th Ft v = K beam Ft v A (21) Besides, K th Fn u and K th Ft v are evaluated as:    K th Fn u = Fn 2 u 1 = a α 2 α 1 N r ( a , 0) u ( b , 0) K th Ft v = Ft 2 v 1 = a α 2 α 1 N r θ a , π 2 v b , π 2 (22)