A constant vertical load was applie

A constant vertical load was applied to the samples with a testing machine, which was
insulated using kaowool. Fume extraction was provided. All samples tested were 10 mm
thick by 100 mm wide. This enabled a region 100 mm square to be exposed to the heat flux.
For the tensile loading, 40 mm long samples were loaded using the wedge grips of the
testing machine. In this mode it was necessary to insulate the upper grip with about 15 mm
thick kaowool to prevent it from overheating, and resulting in premature grip slippage.
For compressive loading, two types of test were carried out. Initially, 150 mm long
samples were simply supported, as in the previously reported compression tests. Global
Euler buckling limited the compressive stress that could be applied to these samples.
In order to achieve higher compressive stresses, nearer to the design stresses that might be
used in some composite structures, additional constraint was provided to delay the onset
of buckling. It was found that an excellent way of accomplishing this, while still allowing
a substantial region of the specimen to be subjected to heat flux, was to use a test jig
with anti-buckling guides similar to the well-known Boeing compression test [24], but with
a square, rather than rectangular sample. The set-up is shown in Figure 5.