PSI - Issue 19

Jan Presse et al. / Procedia Structural Integrity 19 (2019) 423–432 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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3. Experimental Investigation of hybrid joined multi-material connections

To identify major parameters on static and fatigue strength many configurations were tested in this study. First, the tests were performed for each joining technique separately to gain information and consider it on the hybrid configurations. Lap shear (LS) and coach peel (CP) specimens were used as representative for the relevant load cases for each combination. Fig 1 shows the tested specimen as a hybrid joined configuration.

Self-Piercing Rivet Adhesive

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Fig 1. Dimensioning of tested specimen. Above: Lap shear (LS). Below: Coach peel (CP).

The multi-material connections were fabricated with an adhesive and the SPR was applied in the center of the overlap for each load case. The adhesive Teroson EP5089 from Henkel is a one-component epoxy-based structural adhesive. For the configuration, two rivets with a diameter of = 3.35 and = 5.3 from Tucker were applied on the already adhesively bonded but not cured sheets. The configuration has DP600 high strength steel with a thickness of = 0.9 on the head side sheet (top sheet) and EN AW-6016 with a thickness of = 1.5 as tail side sheet (bottom sheet). All configurations were baked at = 170° for 20 minutes, which simulates the E-coating and initiates the heat curing of the adhesive. Experiments under quasi-static shear loads show that hybrid joined connections reach nearly the same maximal load values as only adhesively bonded connections with the same configuration. For the coach peel load case, which is more critical for adhesives to endure, the rivet works as a supporting element after the adhesive fails until a certain level. Therefore the rivet extends the potential of a hybrid joined connection under peel loads, while the adhesive yields most of the shear loads. The cyclic tests were performed with a load ratio of = 0.1 and a frequency of = 10 . The fatigue tests for the LS load case, as seen in Fig 2, confirm the insights from the quasi-static tests. Accordingly, the adhesive seems to carry most of the fatigue strength of the hybrid joined connections under LS load. The fatigue strength values of the only riveted connection are inferior compared to the remaining joining techniques. The highest fatigue strength values