Page 114 - Template Tesis UTM v2.0

3.5.4 Low Velocity Impact Test

Most of the composite structures and parts used in advanced applications are

fibre reinforced composites that should have a service life of 25 to 30 years which

might be subjected to various loading conditions. Therefore, its responses to such
conditions should be clearly understood. Several approaches have been exploited to

enhance the impact damage resistance of composite laminates. The flying fragment or

a drop of tool with low velocity can impact the composite structure, which will cause
damage such as delamination, fibre breakage and matrix failure if the impact energy

is high enough [68]. Many factors affect the impact response and the critical factors
include laminate thickness, lay-up configuration, impactor size, impactor shape,

constituent properties, temperature, impact velocity and energy [132]. Moreover, there
are three distinct interaction modes between laminates and impactor, which are, the

impactor will bounce back if the composite absorbed small energy, no rebound will

occur if most of the impactor’s energy was absorbed by the composite through various
modes of damages such as delamination and matrix cracking, and perforation can be

observed for high energy levels [68]. The typical energy curve for drop-weight impact
test where rebound of the impactor occurs is illustrated in Figure 3.8.

Figure 3.8 A typical energy curve for drop-weight impact test when rebound of
the impactor occur [68]

84