PSI - Issue 14

K. Vijayan et al. / Procedia Structural Integrity 14 (2019) 642–648 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

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For brevity just the images the microscopic images of bad sample are shown in Fig.6. It was observed that the grains are elongated in TMAZ zone and the size the grain size was increasing again in the Weld zone. A key observation was the presence of micro voids in the sample with bad tensile strength.

Fig. 6. Optical microscope images for the samples classified according to the tensile strength showing micro voids.

4. Macroscopic analysis

4.1. Modal analysis and damping

The welded structure was clamped to a built up system as shown in Fig.7. For a built-up system damping can significantly influence the response as stated by Vijayan et al. (2013, 2014). The structure was tested using a vibration shaker to determine the natural frequency and mode shape.

Fig. 7. Experimental set up for modal testing.

The system was modeled using ANSYS APDL. The dimensions as well as the cross sectional details of the system are given in Fig.8. The individual member was modeled as Beam element. The welded section was attached to the built up section using a discrete spring element. The natural frequencies and mode shape type is given in Table 2. The mode shape type was determined by carrying out a modal analysis on the individual components of the