Issue 47

K. Hachellaf et alii, Frattura ed Integrità Strutturale, 47 (2019) 459-467; DOI: 10.3221/IGF-ESIS.47.36 461 Resin's designation Minimal stress Required MSR (MPa) Long-term hydrostatic Stress σ (MPa) PE100 10 8 PE 80 8 6.3 Table 1 : Resin’s used for HDPE tubes [42]. Characteristics Units PE80 PE100 Density kg/m 3 949-956 956-961 Melt Flow Index( MFI (190 °C ; 5kg) g/10 mn 0.7-1 0.2-0.5 Resistance at the yield point MPa ≥15 ≥19 Elongation at break % >600 >600 Elasticity modulus MPa 800 1000 Fragility temperature 0 C <-100 <-100 Linear expansion K -1 24.104 24.104 Electrical resistance Ω/cm ≥1012 ≥1012 Table 2 : Physical characteristics of HDPE [10]. Figure 2: No welded test specimen [12]. Figure 3: Stress-Strain curve (non-welded test specimen) in the strain rate. For the investigation, samples of size 300 mm x 60 mm x 4 mm were used Fig. 4. Butt welding was done. The tools used are prepared by steel commonly used to ensure good mixing and good softening of the material entrained Fig. 5. Figure 4: FSW welding sample.