Page 93 - Template Tesis UTM v2.0

of the bars, respectively, and is the original thickness of the specimen. Length of

striker, incident and transmitted bars are 200, 400 and 400 mm, respectively with the
bar diameter 14.0 mm. The test was done in two directions, in-plane and out

of plane loadings with striker bar moving at 16.5 - 28.5 m/s (corresponding to strain
-1
rates between 500 to 1100 s ). Cylindrical specimens were held in between incident
and transmitter bars with diameter and length of 12.0 and 10.0 mm, respectively. It
was found that the carbon/epoxy showed the strain-rate dependent with

maximum compressive stress and strain were dependent on the applied strain rate. In

terms of failure modes, the specimens primarily damaged in shear mode for out of
plane loading and were independent from loading states and strain rates applied.

During in-plane loading condition, delamination occurred for high strain rates instead

of both shear deformation and delamination found in-plane quasi static loading [118].

Song et al. [119] investigated the effect of strain rates of S-2 glass/epoxy on

the dynamic compression properties and failure mechanism of the tested specimens.
As shown in Figure 2.33, the strain rates applied were sensitive on the compressive

stress-strain curves. In addition, quasi-static indentation test was also done at 0.0001,
-1
0.001, 0.01 and 1.0 s for comparison purposes. Stress-strain curves were linearly
behaviour for quasi-static strain rates instead of non-linear behaviour were observed
at high strain rates. In terms of engineering strain, specimen under quasi-static loading

displayed 2.5 % higher of engineering strain than dynamic loadings. The linear

behaviour of quasi-static stress-strain curves might be explained due to the minor or
no damage occurring in the specimen at small strain rates. However, for the high strain

rates, the slopes of stress-strain curves were decreasing due to the damage induce

caused by the high stress.

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