This research investigates scaling laws for applied loads, residual stresses, and crack driving forces when using scaled models to assess structural integrity and performance of nuclear welded components. Numerical analysis and finite element simulations are used alongside laboratory experiments on different sized four-point bend specimens to study how failure loads scale and how residual stresses differ with specimen size when loaded to equivalent stress intensity factors. The goal is to determine if structural integrity assessments can be accurately predicted using smaller scaled specimens.

1. Summary of research topics: residual stresses, fracture
and structural integrity and scaling.
Paulo Orrock
PhD Student in Solid
Mechanics Research Group

2. Research abstract
For nuclear welded components the complex nature of the
stresses involved means it is often advantageous to produce
mock-ups in order that the structural integrity and performance
may be assessed. The weight and size of these components
can make the production of mock-ups prohibitively expensive
and impractical, and so this project has considered the use of
scaled models.
This investigation focuses on the scaling laws encountered
affecting the applied loads, residual stresses and crack driving
forces. A combination of numerical analyses, finite element
simulations and lab based experiments have been employed,
focusing on fundamental structural integrity tests.

3. The effects of scaling on structural integrity assessments
3
3rd October 2016
Different sized four point bend specimens have been used
to investigate predicting large failure loads from smaller
specimens.
Above: A
small un-
cracked
four point
bend
specimen.
Above: Modeling of cracked four point bend.
Left: A larger cracked four point bend
specimen.

4. The effects of scaling on structural integrity assessments
4
3rd October 2016
Right: Residual stresses in different
sized bend specimens after loading to
same stress intensity factor. 0.0 0.2 0.4 0.6 0.8 1.0
Normalised distance across uncracked ligament
− 800
− 600
− 400
− 200
0
200
400
σyy[MPa]
Large prototype
Small model
0 10 20 30 40 50
K I [M Pa
√
m]
0.0
0.2
0.4
0.6
0.8
1.0
Pf
Large prototype
Small model
Left: Showing change in fracture
toughness associated with scaling