TY  - CONF
AU  - Mastilović, Sreten
AU  - Djordjević, Branislav
AU  - Sedmak, Aleksandar
AU  - Kirin, Snežana
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2098
AB  - The phenomenon of ductile-to-brittle transition (DBT) in ferritic steels, widely used in design of nuclear reactor pres-sure vessels, has been a pervasive semi-centennial research topic. Due to the extremely pronounced experimental data scatter, the statistical approach to characterization of this problem has become inevitable from the earliest analyses. In the present study, the fracture toughness parameters derived from the EURO fracture toughness dataset for 22NiMoCr37 reactor steel are used with the aim to explore the utility of the recently proposed two-step-scaling method. Two widely different temperatures (-154 °C and -91 °C; belonging to the lower shelf and the DBT transition regions of fracture toughness, in respect) are selected to demon-strate the accuracy of extrapolation and interpolation of the fracture toughness CDF (cumulative distribution function) and the pertinent issues related to the method application. The fracture toughness measure used is the critical value of the stress intensity factor used in the master curve KJc (MPa√m). The obtained predictions are in good agreement with the experimental results and well within the inherent experimental data scatter. The prediction of the fracture toughness CDF obtained by extrapolation using the novel two-step-scaling method is reasonably conservative.
PB  - Society for Structural Integrity and Life
C3  - Structural Integrity and Life
T1  - Size Effect Assessment of KJc Experimental Data Using the Two-Step-Scaling Method
EP  - 110
IS  - 2
SP  - 105
VL  - 23
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2098
ER  - 

@conference{
author = "Mastilović, Sreten and Djordjević, Branislav and Sedmak, Aleksandar and Kirin, Snežana",
year = "2023",
abstract = "The phenomenon of ductile-to-brittle transition (DBT) in ferritic steels, widely used in design of nuclear reactor pres-sure vessels, has been a pervasive semi-centennial research topic. Due to the extremely pronounced experimental data scatter, the statistical approach to characterization of this problem has become inevitable from the earliest analyses. In the present study, the fracture toughness parameters derived from the EURO fracture toughness dataset for 22NiMoCr37 reactor steel are used with the aim to explore the utility of the recently proposed two-step-scaling method. Two widely different temperatures (-154 °C and -91 °C; belonging to the lower shelf and the DBT transition regions of fracture toughness, in respect) are selected to demon-strate the accuracy of extrapolation and interpolation of the fracture toughness CDF (cumulative distribution function) and the pertinent issues related to the method application. The fracture toughness measure used is the critical value of the stress intensity factor used in the master curve KJc (MPa√m). The obtained predictions are in good agreement with the experimental results and well within the inherent experimental data scatter. The prediction of the fracture toughness CDF obtained by extrapolation using the novel two-step-scaling method is reasonably conservative.",
publisher = "Society for Structural Integrity and Life",
journal = "Structural Integrity and Life",
title = "Size Effect Assessment of KJc Experimental Data Using the Two-Step-Scaling Method",
pages = "110-105",
number = "2",
volume = "23",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2098"
}

Mastilović, S., Djordjević, B., Sedmak, A.,& Kirin, S.. (2023). Size Effect Assessment of KJc Experimental Data Using the Two-Step-Scaling Method. in Structural Integrity and Life
Society for Structural Integrity and Life., 23(2), 105-110.
https://hdl.handle.net/21.15107/rcub_rimsi_2098

Mastilović S, Djordjević B, Sedmak A, Kirin S. Size Effect Assessment of KJc Experimental Data Using the Two-Step-Scaling Method. in Structural Integrity and Life. 2023;23(2):105-110.
https://hdl.handle.net/21.15107/rcub_rimsi_2098 .

Mastilović, Sreten, Djordjević, Branislav, Sedmak, Aleksandar, Kirin, Snežana, "Size Effect Assessment of KJc Experimental Data Using the Two-Step-Scaling Method" in Structural Integrity and Life, 23, no. 2 (2023):105-110,
https://hdl.handle.net/21.15107/rcub_rimsi_2098 .

TY  - CONF
AU  - Mastilović, Sreten
AU  - Djordjević, Branislav
AU  - sedmak, aleksandar
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2067
AB  - The fracture toughness of ferritic steels in the DTB (ductile-to-brittle) transition temperature region is a stochastic extrinsic property known for pronounced experimental data scatter that necessitates statistical approach in the DTB characterization. The novel two-step-scaling (2SS) method, proposed recently for the size effect-modeling across the DTB transition region, is developed based on the weakest-link statistics and the two-parametric Weibull distribution. Specifically, the size sensitivity of the Weibull parameters of scale and shape are built into the appropriate framework. This approach is upgraded in this article to render the comparison with the existing models more transparent. Specifically, the original 2SS method is enhanced by adding a lower limit on fracture toughness, resulting in the translated (three-parameter) Weibull cumulative distribution function. This third Weibull parameter, often dubbed the location parameter, defines a threshold value that limits the accessible fracture toughness domain. The upgraded 2SS approach is compared to two established methods of the DTB fracture toughness assessment, which favorably reflected upon its generality and application flexibility.
PB  - Serbian Society of Mechanics
C3  - Collection of Articles from the Ninth International Congress of the Serbian Society of Mechanics
T1  - Upgraded Two-Step-Scaling Approach to the DTB Characterization of Ferritic Steels
UR  - https://hdl.handle.net/21.15107/rcub_rimsi_2067
ER  - 

@conference{
author = "Mastilović, Sreten and Djordjević, Branislav and sedmak, aleksandar",
year = "2023",
abstract = "The fracture toughness of ferritic steels in the DTB (ductile-to-brittle) transition temperature region is a stochastic extrinsic property known for pronounced experimental data scatter that necessitates statistical approach in the DTB characterization. The novel two-step-scaling (2SS) method, proposed recently for the size effect-modeling across the DTB transition region, is developed based on the weakest-link statistics and the two-parametric Weibull distribution. Specifically, the size sensitivity of the Weibull parameters of scale and shape are built into the appropriate framework. This approach is upgraded in this article to render the comparison with the existing models more transparent. Specifically, the original 2SS method is enhanced by adding a lower limit on fracture toughness, resulting in the translated (three-parameter) Weibull cumulative distribution function. This third Weibull parameter, often dubbed the location parameter, defines a threshold value that limits the accessible fracture toughness domain. The upgraded 2SS approach is compared to two established methods of the DTB fracture toughness assessment, which favorably reflected upon its generality and application flexibility.",
publisher = "Serbian Society of Mechanics",
journal = "Collection of Articles from the Ninth International Congress of the Serbian Society of Mechanics",
title = "Upgraded Two-Step-Scaling Approach to the DTB Characterization of Ferritic Steels",
url = "https://hdl.handle.net/21.15107/rcub_rimsi_2067"
}

Mastilović, S., Djordjević, B.,& sedmak, a.. (2023). Upgraded Two-Step-Scaling Approach to the DTB Characterization of Ferritic Steels. in Collection of Articles from the Ninth International Congress of the Serbian Society of Mechanics
Serbian Society of Mechanics..
https://hdl.handle.net/21.15107/rcub_rimsi_2067

Mastilović S, Djordjević B, sedmak A. Upgraded Two-Step-Scaling Approach to the DTB Characterization of Ferritic Steels. in Collection of Articles from the Ninth International Congress of the Serbian Society of Mechanics. 2023;.
https://hdl.handle.net/21.15107/rcub_rimsi_2067 .

Mastilović, Sreten, Djordjević, Branislav, sedmak, aleksandar, "Upgraded Two-Step-Scaling Approach to the DTB Characterization of Ferritic Steels" in Collection of Articles from the Ninth International Congress of the Serbian Society of Mechanics (2023),
https://hdl.handle.net/21.15107/rcub_rimsi_2067 .

TY  - 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 .

TY  - CONF
AU  - Djordjević, Branislav
AU  - Mastilović, Sreten
AU  - Sedmak, Aleksandar
AU  - Dimic, Aleksandar
AU  - Sedmak, Simon
AU  - Arandjelovic, Mihajlo
PY  - 2023
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/2069
AB  - The large scatter of the experimental fracture toughness data, characteristic of all ferritic steels in the ductile-to-brittle transition
temperature region, imposed the need to include statistical methods for data processing. Due to the inherent stochasticity, the
application of fracture mechanics concepts in the characterization of the DTB transition phenomenon has remained a challenging
task over the past 50 years. Various models were developed based on statistical approach to data processing in order to capture
the salient features of the phenomenon, but all of them have certain limitations because of the intrinsic complexity of the
problem. However, all these models provided a solid basis for the continued development of new approaches in the
characterization of DTB. Such two novel models are compared herein. They include size effects and utilize scaling of
geometrically similar C(T) specimens, with the aim of obtaining predictions of the fracture toughness. Both proposed models
have the weakest link statistics in common. In the present study, the EURO fracture toughness data set for 22NiMoCr37 reactor
steel is used and the experimental data obtained at temperature of -60 ºC is selected to demonstrate the accuracy of the estimates.
The fracture toughness measure used is the critical value of the stress intensity factor used in the master curve KJc [MPa√m].
The obtained predictions are in good agreement with the experimental results, taking into account the inherent scatter of the
experimental data. The estimate of KJc cumulative distribution function obtained by extrapolation using the novel two-stepscaling
method is sensitive to the statistical size of the input data sets.
PB  - Elsevier B.V.
C3  - Procedia Structural Integrity
T1  - Comparison of two recent approaches to DTB characterization of ferritic steels
EP  - 596
SP  - 589
VL  - 47
DO  - 10.1016/j.prostr.2023.07.065
ER  - 

@conference{
author = "Djordjević, Branislav and Mastilović, Sreten and Sedmak, Aleksandar and Dimic, Aleksandar and Sedmak, Simon and Arandjelovic, Mihajlo",
year = "2023",
abstract = "The large scatter of the experimental fracture toughness data, characteristic of all ferritic steels in the ductile-to-brittle transition
temperature region, imposed the need to include statistical methods for data processing. Due to the inherent stochasticity, the
application of fracture mechanics concepts in the characterization of the DTB transition phenomenon has remained a challenging
task over the past 50 years. Various models were developed based on statistical approach to data processing in order to capture
the salient features of the phenomenon, but all of them have certain limitations because of the intrinsic complexity of the
problem. However, all these models provided a solid basis for the continued development of new approaches in the
characterization of DTB. Such two novel models are compared herein. They include size effects and utilize scaling of
geometrically similar C(T) specimens, with the aim of obtaining predictions of the fracture toughness. Both proposed models
have the weakest link statistics in common. In the present study, the EURO fracture toughness data set for 22NiMoCr37 reactor
steel is used and the experimental data obtained at temperature of -60 ºC is selected to demonstrate the accuracy of the estimates.
The fracture toughness measure used is the critical value of the stress intensity factor used in the master curve KJc [MPa√m].
The obtained predictions are in good agreement with the experimental results, taking into account the inherent scatter of the
experimental data. The estimate of KJc cumulative distribution function obtained by extrapolation using the novel two-stepscaling
method is sensitive to the statistical size of the input data sets.",
publisher = "Elsevier B.V.",
journal = "Procedia Structural Integrity",
title = "Comparison of two recent approaches to DTB characterization of ferritic steels",
pages = "596-589",
volume = "47",
doi = "10.1016/j.prostr.2023.07.065"
}

Djordjević, B., Mastilović, S., Sedmak, A., Dimic, A., Sedmak, S.,& Arandjelovic, M.. (2023). Comparison of two recent approaches to DTB characterization of ferritic steels. in Procedia Structural Integrity
Elsevier B.V.., 47, 589-596.
https://doi.org/10.1016/j.prostr.2023.07.065

Djordjević B, Mastilović S, Sedmak A, Dimic A, Sedmak S, Arandjelovic M. Comparison of two recent approaches to DTB characterization of ferritic steels. in Procedia Structural Integrity. 2023;47:589-596.
doi:10.1016/j.prostr.2023.07.065 .

Djordjević, Branislav, Mastilović, Sreten, Sedmak, Aleksandar, Dimic, Aleksandar, Sedmak, Simon, Arandjelovic, Mihajlo, "Comparison of two recent approaches to DTB characterization of ferritic steels" in Procedia Structural Integrity, 47 (2023):589-596,
https://doi.org/10.1016/j.prostr.2023.07.065 . .

TY  - JOUR
AU  - Mastilović, Sreten
PY  - 2022
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1598
AB  - The present investigation relies upon an
alternative approach to estimate the penetration depth
of rigid projectiles into quasibrittle materials that utilizes
simulation-informed modeling of penetration
resistance. Penetration at normal incidence of a long
rigid rod into massive targets, made of materials with
inferior tensile strength predisposed to microcracking,
is an event characterized by a high level of aleatory
variability and epistemic uncertainty. This inherent
stochasticity of the phenomenon is addressed by a
model developed based on the particle dynamics (PD)
simulations aimed to provide a key modeling ingredient—
the functional dependence of the radial traction
at the cavity surface on the radial velocity of the cavity
expansion. The penetration depth expressions are
derived for the ogive nose projectiles. The use of the
power law radial traction dependence upon the expansion
rate yields the penetration resistance and depth
equations defined in terms of hypergeometric functions.
These expressions are readily evaluated and
offer a reasonably conservative estimate of the penetration
depth. This model is validated by using experimental
results of the penetration depth of long projectiles
into Salem limestone, which is a typical example
of quasibrittle materials with random microstructure
well known for their pronounced experimental data
scatter. This stochasticity is explored in the present
paper by a sensitivity analysis of the key input parameters
of the model; most notably, uniaxial tensile
strength and friction coefficient.
PB  - Springer Nature
T2  - Meccanica
T1  - A PD simulation‑informed prediction of penetration depth of rigid rods through materials susceptible to microcracking
EP  - 3069
IS  - 12
SP  - 3051
VL  - 57
DO  - 10.1007/s11012-022-01614-5
ER  - 

@article{
author = "Mastilović, Sreten",
year = "2022",
abstract = "The present investigation relies upon an
alternative approach to estimate the penetration depth
of rigid projectiles into quasibrittle materials that utilizes
simulation-informed modeling of penetration
resistance. Penetration at normal incidence of a long
rigid rod into massive targets, made of materials with
inferior tensile strength predisposed to microcracking,
is an event characterized by a high level of aleatory
variability and epistemic uncertainty. This inherent
stochasticity of the phenomenon is addressed by a
model developed based on the particle dynamics (PD)
simulations aimed to provide a key modeling ingredient—
the functional dependence of the radial traction
at the cavity surface on the radial velocity of the cavity
expansion. The penetration depth expressions are
derived for the ogive nose projectiles. The use of the
power law radial traction dependence upon the expansion
rate yields the penetration resistance and depth
equations defined in terms of hypergeometric functions.
These expressions are readily evaluated and
offer a reasonably conservative estimate of the penetration
depth. This model is validated by using experimental
results of the penetration depth of long projectiles
into Salem limestone, which is a typical example
of quasibrittle materials with random microstructure
well known for their pronounced experimental data
scatter. This stochasticity is explored in the present
paper by a sensitivity analysis of the key input parameters
of the model; most notably, uniaxial tensile
strength and friction coefficient.",
publisher = "Springer Nature",
journal = "Meccanica",
title = "A PD simulation‑informed prediction of penetration depth of rigid rods through materials susceptible to microcracking",
pages = "3069-3051",
number = "12",
volume = "57",
doi = "10.1007/s11012-022-01614-5"
}

Mastilović, S.. (2022). A PD simulation‑informed prediction of penetration depth of rigid rods through materials susceptible to microcracking. in Meccanica
Springer Nature., 57(12), 3051-3069.
https://doi.org/10.1007/s11012-022-01614-5

Mastilović S. A PD simulation‑informed prediction of penetration depth of rigid rods through materials susceptible to microcracking. in Meccanica. 2022;57(12):3051-3069.
doi:10.1007/s11012-022-01614-5 .

Mastilović, Sreten, "A PD simulation‑informed prediction of penetration depth of rigid rods through materials susceptible to microcracking" in Meccanica, 57, no. 12 (2022):3051-3069,
https://doi.org/10.1007/s11012-022-01614-5 . .