JEC COMPOSITES MAGAZINE - Issue #103 - March 2016 - 78

testing

Fig. 5: Vertical cantilever bending test (see [14, 15])

The specimen (50mm * 200mm) is fixed at the top and
deflected by a weight that is connected to the specimen by a
rope (figure 4). In this study, the deflection is measured with
a measuring scale fixed at the back of the thermal chamber
(figure 5). During the heating time, pre-tests showed that the
specimens started to deflect towards the side of the rod also
when there was no weight. Thus, the thermal chamber was
fitted to a universal testing machine to fix the free end of the
specimen with a forked tool connected to the testing machine.
When the defined temperature is reached, the tool moves
down after a holding time of five minutes. Within this time,
there may be a relaxation of residual stresses within the specimen. The advantage of this test is that the setup is simple and
the test starts after the defined temperature has been reached.
The disadvantage is that the friction between the pulley and
the rod may influence the test results.

Results and discussion
The test specimens were made of one layer of glass twill fabric
with polyamide 6 from Bond Laminates (TEPEX® Dynalite
102-RG600(1)/47%). Figures 6 and 7 show the overhanging
length or displacement of the free edge of the test specimens
for the cantilever bending test (moved) and the vertical bending test. When the temperature increases, the deflection of
the specimen increases due to its decreasing bending stiffness.
This results in a decreasing overhanging length (figure 2) of
the cantilever bending test (figure 6) until the test specimen
touches the indicator surface, and an increasing displacement,
measured in the X and Y directions (figure 5), of the free edge
of the vertical bending test (figure 7).
The cantilever bending test (moved) was tested with different
orientations (0°/90° and ± 45°) of the fibres to the platform
edge. Figure 6 shows that the bending stiffness is much lower
for a fibre orientation of ± 45° compared to 0°/90°, where the
warp direction is parallel to the platform edge and thus to the
sliding direction. The test results for a temperature of 220°C
show a large scatter. The melting temperature of polyamide 6
is about 220°C. Thus, the specimens may have areas that are

78 jec composites magazine / No103 March 2016

Fig. 6: Test results (cantilever bending test (moved))

Fig. 7: Test results (vertical bending test)

not completely melted, leading to a different bending stiffness
of different specimens. The overhanging length for temperatures above the melting temperature (240°C and 260°C) do
not show significant differences. This leads to the assumption
that increasing temperature above the melting temperature
does not affect the bending stiffness. Liang et al. [12] also
showed that the deflection of the tested PPS/satin specimens
is nearly the same for different tested temperatures above the
melting temperature of PPS.
Silicone foils were tested without the FRT between them for
the temperature values defined in this study in order to consider
the influence of their bending stiffness in an FE analysis. Their
overhanging length was about 21mm for each temperature.
The test results of the vertical bending test were evaluated in
the form of X and Y coordinates of the free edge. This leads to
simple result values for the validation of simulation results in
further studies.
In this case, there is a significant scatter for all the tested
temperatures. The displacement in the Y direction is nearly
the same at 240°C and 260°C, but the displacement in the

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #103 - March 2016