PSI - Issue 47

A. Califano et al. / Procedia Structural Integrity 47 (2023) 842–848 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Table 1: Classification of joints according to the welding parameters.

Joint Class

Laser Power [kW]

Laser Speed [mm/s]

Laser Focus [mm]

A B C D E F

3.0 3.0 3.0 3.0 3.0 3.0

30 35 40 30 35 40

0.0 0.0 0.0 -3.0 -3.0 -3.0

A schematization of a single lap joint, together with sizes and dimensions, is reported in Figure 1. It can be noticed that the overlapping region had a length of 30 mm, hence the final joint had in-plane sizes 200 mm x 170 mm. Then, seven slices were obtained by cutting each joint perpendicularly to the welding direction with a width of 21 mm later these were milled to obtain the final specimens with width of 20 mm. Therefore, fourteen specimens for each class (seven from the first joint and seven from the second joint) were available. At this point, for carrying out the mechanical testing, six specimens (one for each class) were selected and named 1A1, 1B1, 1C1, 1D1, 1E1 and 1F1. Each of the six specimens was equipped with two strain-gauges (named S1 and S2), one for each side of the welding bead, with the aim of measuring the local axial deformations of the welded zone. In particular, S1 was glued on the same face as that of the welding bead, while S2 was glued on the opposite face of the specimen. The chosen strain-gauges were the HBM LY71-1.5/120 (120 Ohm of nominal electrical resistance) that were bonded on the specimens through HBM Z70 cyanoacrylate glue. A layout of strain gauges is reported in Figure 2a, while a picture of an actual specimen (1B1) in reported in Figure 2b. Each of the six specimens was subjected to a static tensile test, according to the ASTM E8 (2016) by using a MTS Insight 30 testing machine equipped with a load cell of 30 kN and using a crosshead speed of 1.5 mm/min.

Fig. 1. Drawing of a single lap joint.

Specimens were mounted onto the machine with the S1 strain-gauge above the welding bead.