cranfield university mahadi abd murad an integrated structural ...

One of the objectives of doing this was to validate the numerical stress
concentration results. The same procedures were repeated in the second stage of Test 1
but this time the main objective was to observe how well the strains and stresses in the
composite follow the strains and stresses in the pipe due to internal pressure loading.
Hence, it would provide some insights into load transfer between steel and composite
and the stress transfer through the epoxy matrix. A detailed description of the strain
measurement methodology will be explained in the following section.
4.4.2 Detailed descriptions of strain measurement
Figures 4.12 and 4.13 show there were three locations of strain measurement
(i.e. at base, middle and top or outer layer of the composite repair). Points 1a, b and c
were referred to the points on the steel pipe (i.e. base). At point 1a (i.e. at the notch
root), there were three strain gauges installed along the circumferential notch root as
shown in Figure 4.14. Points 2a and b were referred to the 4 th layer of the composite
lamina (half of the composite thickness – middle layer) and Point 3a and b were referred
to the outer layer (8 th layer – top layer) of the composite. The measuring distance of
strain gauge from the point away from the defect (nominal thickness) to the defect area
on each layer was about 80 ~ 90 mm.
Figure 4.82: A schematic representation of the measuring point locations
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