PSI - Issue 57

Kaushik Iyer et al. / Procedia Structural Integrity 57 (2024) 469–477 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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This study builds on the work done by (Hagnell, et al. 2021) and assesses the impact of post-weld treatments on a welded structure from an economic perspective. The methodology section depicts the equations and methodology behind this predictive life-cycle costing and fatigue strength evaluation of a HFMI-treated welded specimen. The results section shows and assesses the effect of the corresponding PWT on the manufacturing cost and the Life-cycle cost of the welded structure. The study also assesses the effect of weld geometry and weld lengths on the fatigue life and correspondingly, the life-cycle cost of the welded structure. Finally, the discussion and the conclusion sections draw important and relevant implications from the results. Nomenclature LCC Life-cycle Costing NS Effective Notch Stress Method PWT Post-weld Treatment EOL End-of-life HFMI High-Frequency Mechanical Impact 2. Case Study The developed predictive cost model for the post-weld treatment is applied to a cruciform weld. The cruciform weld is assumed to be a non-load carrying welded structure with a full penetration level. Furthermore, it also assumed that the cause of failure of the weld occurs in the weld toe, thus making PWTs applicable for life-extension. The geometries of the cruciform weld including the plate thicknesses, weld lengths, and leg lengths are given in Table 1. An idealized weld geometry was assumed for the study; the weld angle was set to 45° (Figure 2). An as welded sample and a HFMI treated welded sample are compared. Further details of the fatigue analysis methodology are given in section 3.1. This study is performed on a sample level to generalize the study results and to investigate the cost and fatigue life improvements gained by the PWT irrespective of the weld placement or the product geometry. To evaluate the cost incurred by the use-phase, the weld is assumed to be incorporated in a larger welded box for load handling applications. Further details about the box geometry can be found in (Hagnell, et al. 2021).

Figure 2 Schematic of the weld geometry being analysed. Note: P is the load applied and a is the weld throat thickness.

Table 1: Weld geometries

Sample 1

Sample 2 12 mm

Plate thickness

6 mm