PSI - Issue 33

Jamaloddin Jamali et al. / Procedia Structural Integrity 33 (2021) 832–842 Auth r name / Structural Integrity Procedia 00 (2019) 000–0 0

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Fig. 13: Force vs. displacement curve for SENB specimens having different thicknesses.

According to Fig. 13 the specimens with thickness 15 mm had the lowest displacement value and thickness 20 mm had the highest displacement value. The values of fracture toughness for SENB specimens having thickness of 15 mm are shown in figure 14.

Fig 14: The calculated fracture toughness for some of the polyester SENB specimens in MPa.√m

6.3. CT Testing The values of force at which crack propagates is measured by UTM and the values of fracture toughness in MPa. √m is calculated using equation 2. The results are shown in Fig. 15. It should be noted that while the values of Fig. 15 are in MPa. √m, the results of fracture toughness using SENB in Fig. 13 are shown in MPa. √mm .