Page 92 - Template Tesis UTM v2.0

and modulus are highly dependent on the strain rate whereby higher dynamic

compression properties were recorded by the tested specimens when the higher strain
rates were applied [116].

The application of composite materials in composite armor and naval
structures required the characterisation of through thickness properties. Govender et

al. [117] has conducted the quasi-static and SHPB tests on glass/vinyl ester specimens
-1
-1
at 1.0 mm/min ( = 2.5 x 10-3 s ) and 5100 s , respectively. Result showed that the
higher the strain rate, the higher compressive strength is shown by the specimens. The

quasi-static exhibited the compressive stress of 417 MPa, which is 9.74 % less than
SHPB (462 MPa).

Song et al. [118] investigated the compressive behaviour of woven

carbon/epoxy using SHPB apparatus. One-dimensional stress wave theory was applied
to determine the engineering stress, engineering strain and strain rate as shown in the

Equations 2.1, 2.2 and 2.3, respectively.

( ) = ( + + ) (2.1)

2

( ) = ∫ ( + + ) (2.2)

0

̇ ( ) = ( + + ) (2.3)

Meanwhile, wave speed can be determined using Equation 2.4 below;

= √ (2.4)

Where; and are the cross-section area of the bars and specimen, , and

are uniaxial elastic stress wave speed in pressure bars, density and Young’s modulus
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