PSI - Issue 52

Ben M B Sargeant et al. / Procedia Structural Integrity 52 (2024) 472–479 Ben M B Sargeant , Catrin M Davies and Paul A Hooper / Structural Integrity Procedia 00 (2023) 151-158

473

152

1. Introduction Small sized samples make laboratory testing more convenient. Machine capacity, ease of sample handling and bulk material availability all lend benefit to the use of small test samples. Fracture toughness is used to inform safety cases and component lifespan predictions, but sample size is known to have a major influence on fracture toughness results. Therefore, the influence of sample size on fracture toughness values needs to be quantified. This research evaluated the effect of sample size on fracture toughness of single edge notched bend, SEN(B), geometry samples made from identical pressure vessel steel SA508. Fracture toughness and normalised load displacement curves were compared for two sample sizes (10 mm and 25 mm in thickness and width) but with the same non-dimensional geometry and crack length ratios.

Nomenclature a

Sample crack length

Plastic component to the area under load-displacement curve

A p

Sample thickness

B

Critical sample thickness

B 0

Compliance

C E

Elastic Young’s modulus J-integral fracture toughness J-integral from initial crack length

J

J 0

Elastic component of J-integral from initial crack length Plastic component of J-integral from initial crack length

J e0 J p0 J IC K C K IC K

Critical J-integral fracture toughness

Stress intensity factor

Critical plane stress intensity factor Critical plane strain stress intensity factor

LLD

Load line displacement

Applied load

P

PD

Potential difference Radius of plastic zone

r p

S Sample Span SEN(B) Single edge notch bending V 0 Initial voltage ν Poisson’s ratio W Sample width σ y Yield stress of material σ B Bending stress from loading