PSI - Issue 33

M.F.M.O. Rosas et al. / Procedia Structural Integrity 33 (2021) 115–125 Rosas et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 10 shows the P -  curves of the tubular joints with the change of  at the ends of the tubular adhesive joint, showing aluminium plasticization for all  . According to the results, P m increases with the reduction of  , showing an maximum increase of 3.5% for  =7.5º, over  =90º. However, the increase in joint strength is not significant for this adhesive and the tested geometry conditions due to the adherend plasticity event, which limits P m . 3.3. Geometry combinations After the individual analysis of the three individual geometry modifications in Section 3.2, a combination of modifications is analyzed, namely the merge of an inner chamfer with an adhesive fillet. Actually, this is the only set of individual combinations that can be merged, since the outer chamfer cancels the possibility to add an adhesive fillet that has a heigh t equal to the tubes’ thickness. The main purpose of this study is to promote and eventually add the reduction of stresses imposed by both individual modifications, together with the artificial L O increase with adhesive material. Only a set of inner chamfer and fillet combination was selected, i.e., those representing the best P m results as an individual modification. Thus, for the Araldite ® 2015,  =30º and  =7.5º will be numerically tested. Fig. 11 details the mesh created at one of the overlap edges, with emphasis to the triangular regions of adhesive corresponding to the chamfer and fillet.

Fig. 11. Mesh detail for the geometry combination joint.

Fig. 12 compares the numerical P -  curves between the unmodified joint and the joint combining the inner chamfer with the fillet. From these curves, it is visible that necking takes place in the inner aluminum tube by the steady-state region of P after yielding is reached. This means that, for both configurations, the adhesive layer gains the capacity sustain the applied load and that it becomes more resistant to the adherends. Table 3 compares P m for the two joints, along with the percentile improvement (  P m ). A relatively small strength improvement was found, of approximately 3.5%, due to the event of adherend plasticization. Was not this occurrence, the expected strength improvement would be more significant.

50

40

30

P [kN]

20

10

0

0

0.2

0.4

0.6

0.8

1

1.2

 [mm]

Combination

Standard

Fig. 12. Numerical P -  curves for the unmodified joint and the joint combining the inner chamfer with the fillet.

Table 3. P m [N] for the unmodified and geometry combination joints, and respective  P m . P m [N]  P m [%] Unmodified 40126 Combination 41526 3.5