PSI - Issue 2_A

Nedeljko Vukojević et al. / Procedia Structural Integrity 2 (2016) 2982 – 2988 Author name / Structural Integrity Procedia 00 (2016) 000–000

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3. Statistical analysis using Weibull probability distribution Testing probability distribution shows that the distribution does not follow the Gauss's normal distribution, than an asymmetric curve, for example, Weibull's probability function, indicate references Vukojevic et al. (2015). Weibull distribution function is partly leaning on empirical approach. Determining the probability of the existence P s was made with the assumption that all the specimens were subjected to a same test conditions. For each test obtained the corresponding probability of existence which is determined from equation: ܲ ௦ ൌ ͳ െ ே ଵି ା ଴ ଴ ǡ ǡ ଷ ସ (4) Probability of failure of the sample volume V at the critical value of the stress intensity factor is defined as: ܲ ௦ ሺܸሻ ൌ ݁ ݔ ݌ ቂെܸ ቀ ௄ ಺೎ ି௄ ೠ ௄ ೚ ቁ ௠ ቃ (5) Results of statistical analysis using the Weibull's distribution function are shown in Figures 2, 3 and 4.

Specimens from middle of vessel "M"

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Experiment m=8,731 K o =167,793 MPa·m ½ K u =0 P f (K Ic )= ݁ ݔ ݌ [−(( ܭ Ic − ܭ u )/ ܭ o )] ݉ Experiment

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Probability P s , %

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Stress intensity factor, K Ic 90

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Fig. 2. Weibull diagram for specimens from vessel middle