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Sensitivity study of crack driving force predictions in heterogeneous welds using Vickers hardness maps

Sameera Naib (UGent) , Koen Van Minnebruggen (UGent) , Wim De Waele (UGent) and Stijn Hertelé (UGent)
Author
Organization
Abstract
Welds unavoidably contain flaws which often require an engineering critical assessment (ECA) to judge on the necessity for weld repair. ECA is a fracture mechanics based prediction of the response of welds under applied operating conditions. The estimation of crack driving force, commonly expressed in terms of J-integral or crack tip opening displacement is essential for ECA. An important factor adding to the complexity of an ECA is the occurrence of local constitutive property variations in weldment (‘weld heterogeneity’). A quantification of these variations is important to allow for an accurate assessment. Hardness measurements are widely accepted as an experimental technique to estimate local strength properties, as hardness is known to correlate ultimate tensile strength. However, various standards and procedures report wide variety of possible transfer functions between hardness and strength characteristics. Additionally, they also recognize the scattered nature of these functions. A comparison between transfer functions and experimental stress-strain data reveal substantial variations that may put the suitability of hardness mapping to estimate weld heterogeneity in question. To answer this question, a finite element analysis program has been conducted on welded structural steels to simulate the crack driving force response of welded single-edge notched tension (SE(T)) specimens. SE(T) specimens have gained popularity for the characterization of crack growth resistance properties under low crack tip constraint conditions. Hardness values from Vickers hardness maps are assigned to individual elements in the model and transformed into constitutive properties using different transfer functions. The resulting crack driving force curves are probed against experimentally obtained test results. The variable nature of agreement between simulations and experiments highlights the need for further research into the characterization of local constitutive properties of heterogeneous welds.
Keywords
Crack driving force, Weld, Heterogeneity, SE(T) specimen, Vickers hardness

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MLA
Naib, Sameera, Koen Van Minnebruggen, Wim De Waele, et al. “Sensitivity Study of Crack Driving Force Predictions in Heterogeneous Welds Using Vickers Hardness Maps.” NAFEMS India Conference. Bangalore: NAFEMS 3D, 2016. 77. Print.
APA
Naib, S., Van Minnebruggen, K., De Waele, W., & Hertelé, S. (2016). Sensitivity study of crack driving force predictions in heterogeneous welds using Vickers hardness maps. NAFEMS India Conference (p. 77). Presented at the NAFEMS India Conference, Bangalore: NAFEMS 3D.
Chicago author-date
Naib, Sameera, Koen Van Minnebruggen, Wim De Waele, and Stijn Hertelé. 2016. “Sensitivity Study of Crack Driving Force Predictions in Heterogeneous Welds Using Vickers Hardness Maps.” In NAFEMS India Conference, 77. Bangalore: NAFEMS 3D.
Chicago author-date (all authors)
Naib, Sameera, Koen Van Minnebruggen, Wim De Waele, and Stijn Hertelé. 2016. “Sensitivity Study of Crack Driving Force Predictions in Heterogeneous Welds Using Vickers Hardness Maps.” In NAFEMS India Conference, 77. Bangalore: NAFEMS 3D.
Vancouver
1.
Naib S, Van Minnebruggen K, De Waele W, Hertelé S. Sensitivity study of crack driving force predictions in heterogeneous welds using Vickers hardness maps. NAFEMS India Conference. Bangalore: NAFEMS 3D; 2016. p. 77.
IEEE
[1]
S. Naib, K. Van Minnebruggen, W. De Waele, and S. Hertelé, “Sensitivity study of crack driving force predictions in heterogeneous welds using Vickers hardness maps,” in NAFEMS India Conference, Bangalore, India, 2016, p. 77.
@inproceedings{8058089,
  abstract     = {{Welds unavoidably contain flaws which often require an engineering critical assessment (ECA) to judge on the necessity for weld repair. ECA is a fracture mechanics based prediction of the response of welds under applied operating conditions. The estimation of crack driving force, commonly expressed in terms of J-integral or crack tip opening displacement is essential for ECA. An important factor adding to the complexity of an ECA is the occurrence of local constitutive property variations in weldment (‘weld heterogeneity’). A quantification of these variations is important to allow for an accurate assessment. Hardness measurements are widely accepted as an experimental technique to estimate local strength properties, as hardness is known to correlate ultimate tensile strength. However, various standards and procedures report wide variety of possible transfer functions between hardness and strength characteristics. Additionally, they also recognize the scattered nature of these functions. A comparison between transfer functions and experimental stress-strain data reveal substantial variations that may put the suitability of hardness mapping to estimate weld heterogeneity in question. To answer this question, a finite element analysis program has been conducted on welded structural steels to simulate the crack driving force response of welded single-edge notched tension (SE(T)) specimens. SE(T) specimens have gained popularity for the characterization of crack growth resistance properties under low crack tip constraint conditions. Hardness values from Vickers hardness maps are assigned to individual elements in the model and transformed into constitutive properties using different transfer functions. The resulting crack driving force curves are probed against experimentally obtained test results. The variable nature of agreement between simulations and experiments highlights the need for further research into the  characterization of local constitutive properties of heterogeneous welds.}},
  author       = {{Naib, Sameera and Van Minnebruggen, Koen and De Waele, Wim and Hertelé, Stijn}},
  booktitle    = {{NAFEMS India Conference}},
  keywords     = {{Crack driving force,Weld,Heterogeneity,SE(T) specimen,Vickers hardness}},
  language     = {{eng}},
  location     = {{Bangalore, India}},
  publisher    = {{NAFEMS 3D}},
  title        = {{Sensitivity study of crack driving force predictions in heterogeneous welds using Vickers hardness maps}},
  year         = {{2016}},
}