A Note on the Effect of Statistical Sample Size on Fracture Toughness Characterization in the DTB Transition Region
Abstract
The ferritic steels, widely used as pressure-vessel materials in nuclear industry, are prone to embrittlement when exposed to neutron irradiation or temperature reduction within the DTB (ductile-to-brittle) transition region. This embrittlement may be accompanied by the increased size effect, which is a pronounced consequence of fracture mechanics not exhibited in the traditional plasticity theory. Therefore, the fracture toughness in the DTB transition temperature region is a stochastic extrinsic property well known for its aleatory variability. Consequently, the extremely-pronounced experimental data scatter necessitates the use of the statistical approach to material characterization. The recently proposed two-step-scaling approach to estimate the size effect of fracture toughness CDF (cumulative density function) in the DTB transition region relies heavily on regularity of arrangement of experimental data points for the two input sample sizes. This regularity of measurement values ...becomes an inherently iffy proposition in the case of statistically small data sets. Therefore, the ability of our novel approach to predict objectively the fracture toughness probability outside the experimental domain may be impaired in absence of the sufficient statistical size of the input data sets. Since the large-scale fracture toughness tests for nuclear pressure-vessel steels at low temperatures are very expensive, the present study is concerned with this issue of the statistically sufficient sample size. There are various statistical techniques to determine the sample size needed for a study, including power analysis and sample size calculation formulas. The appropriate method depends on the type of study, the research question, and the statistical analysis planned. These issues are addressed in this article.
Keywords:
ferritic steels / embrittlement / fracture toughness / size effect / statistical sizeSource:
Collection of Articles Presented at the Ninth International Congress of the Serbian Society of Mechanics (July 5-7, 2023, Vrnjačka Banja, Serbia), 2023Publisher:
- Serbian Society of Mechanics
Funding / projects:
- This research was supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia.
Note:
- The papers presented at the Ninth International Congress of the Serbian Society of Mechanics (July 5-7, 2023, Vrnjačka Banja, Serbia) were not published in the usual proceedings format, neither in paper nor in electronic form, but only as a collection of peer-reviewed and accepted articles published at the congress internet site.
Collections
Institution/Community
Institut za multidisciplinarna istraživanjaTY - CONF AU - Mastilović, Sreten AU - Djordjević, Branislav AU - Sedmak, Aleksandar PY - 2023 UR - http://rimsi.imsi.bg.ac.rs/handle/123456789/2068 AB - The ferritic steels, widely used as pressure-vessel materials in nuclear industry, are prone to embrittlement when exposed to neutron irradiation or temperature reduction within the DTB (ductile-to-brittle) transition region. This embrittlement may be accompanied by the increased size effect, which is a pronounced consequence of fracture mechanics not exhibited in the traditional plasticity theory. Therefore, the fracture toughness in the DTB transition temperature region is a stochastic extrinsic property well known for its aleatory variability. Consequently, the extremely-pronounced experimental data scatter necessitates the use of the statistical approach to material characterization. The recently proposed two-step-scaling approach to estimate the size effect of fracture toughness CDF (cumulative density function) in the DTB transition region relies heavily on regularity of arrangement of experimental data points for the two input sample sizes. This regularity of measurement values becomes an inherently iffy proposition in the case of statistically small data sets. Therefore, the ability of our novel approach to predict objectively the fracture toughness probability outside the experimental domain may be impaired in absence of the sufficient statistical size of the input data sets. Since the large-scale fracture toughness tests for nuclear pressure-vessel steels at low temperatures are very expensive, the present study is concerned with this issue of the statistically sufficient sample size. There are various statistical techniques to determine the sample size needed for a study, including power analysis and sample size calculation formulas. The appropriate method depends on the type of study, the research question, and the statistical analysis planned. These issues are addressed in this article. PB - Serbian Society of Mechanics C3 - Collection of Articles Presented at the Ninth International Congress of the Serbian Society of Mechanics (July 5-7, 2023, Vrnjačka Banja, Serbia) T1 - A Note on the Effect of Statistical Sample Size on Fracture Toughness Characterization in the DTB Transition Region UR - https://hdl.handle.net/21.15107/rcub_rimsi_2068 ER -
@conference{ author = "Mastilović, Sreten and Djordjević, Branislav and Sedmak, Aleksandar", year = "2023", abstract = "The ferritic steels, widely used as pressure-vessel materials in nuclear industry, are prone to embrittlement when exposed to neutron irradiation or temperature reduction within the DTB (ductile-to-brittle) transition region. This embrittlement may be accompanied by the increased size effect, which is a pronounced consequence of fracture mechanics not exhibited in the traditional plasticity theory. Therefore, the fracture toughness in the DTB transition temperature region is a stochastic extrinsic property well known for its aleatory variability. Consequently, the extremely-pronounced experimental data scatter necessitates the use of the statistical approach to material characterization. The recently proposed two-step-scaling approach to estimate the size effect of fracture toughness CDF (cumulative density function) in the DTB transition region relies heavily on regularity of arrangement of experimental data points for the two input sample sizes. This regularity of measurement values becomes an inherently iffy proposition in the case of statistically small data sets. Therefore, the ability of our novel approach to predict objectively the fracture toughness probability outside the experimental domain may be impaired in absence of the sufficient statistical size of the input data sets. Since the large-scale fracture toughness tests for nuclear pressure-vessel steels at low temperatures are very expensive, the present study is concerned with this issue of the statistically sufficient sample size. There are various statistical techniques to determine the sample size needed for a study, including power analysis and sample size calculation formulas. The appropriate method depends on the type of study, the research question, and the statistical analysis planned. These issues are addressed in this article.", publisher = "Serbian Society of Mechanics", journal = "Collection of Articles Presented at the Ninth International Congress of the Serbian Society of Mechanics (July 5-7, 2023, Vrnjačka Banja, Serbia)", title = "A Note on the Effect of Statistical Sample Size on Fracture Toughness Characterization in the DTB Transition Region", url = "https://hdl.handle.net/21.15107/rcub_rimsi_2068" }
Mastilović, S., Djordjević, B.,& Sedmak, A.. (2023). A Note on the Effect of Statistical Sample Size on Fracture Toughness Characterization in the DTB Transition Region. in Collection of Articles Presented at the Ninth International Congress of the Serbian Society of Mechanics (July 5-7, 2023, Vrnjačka Banja, Serbia) Serbian Society of Mechanics.. https://hdl.handle.net/21.15107/rcub_rimsi_2068
Mastilović S, Djordjević B, Sedmak A. A Note on the Effect of Statistical Sample Size on Fracture Toughness Characterization in the DTB Transition Region. in Collection of Articles Presented at the Ninth International Congress of the Serbian Society of Mechanics (July 5-7, 2023, Vrnjačka Banja, Serbia). 2023;. https://hdl.handle.net/21.15107/rcub_rimsi_2068 .
Mastilović, Sreten, Djordjević, Branislav, Sedmak, Aleksandar, "A Note on the Effect of Statistical Sample Size on Fracture Toughness Characterization in the DTB Transition Region" in Collection of Articles Presented at the Ninth International Congress of the Serbian Society of Mechanics (July 5-7, 2023, Vrnjačka Banja, Serbia) (2023), https://hdl.handle.net/21.15107/rcub_rimsi_2068 .