Tan, Chin Yeong
(2013)
Impact Response Of Fiber Metal Laminates And Aluminum Composite Sandwich Structures.
Masters thesis, Universiti Sains Malaysia.
Abstract
Fiber metal laminates (FMLs) were prepared by laminating aluminum sheets
with glass fiber-reinforced thermoplastic prepreg. The tensile properties of the FMLs
were characterized using a Universal Test Machine (UTM). The sandwich structure
consists of FMLs skin and polypropylene (PP) honeycomb core is then subjected to
flexural test to determine its flexural properties prior to drop-weight impact tests.
Force-time history were recorded and analyzed from the impact test. Comparisons
between aluminum (AL) skin and FMLs on impact response were investigated using
various impact-sensitive parameters such as impact force-time history, maximum
impact load, contact duration and total absorbed energy. It was found that both skin
types showed plateauing of maximum impact force occurred at impact energy higher
than 12.36J. This suggested that the impact damage threshold energy for both skin
types with PP honeycomb core sandwich structure are 12.36J. However, FMLs
samples showed a better energy absorbing capabilities compared to AL samples. It
was found that the contact duration was significantly higher for samples which show
global bending on the structure. Post-impact damage evaluations were also carried
out by comparing the damage area between optical and C-scan method. As a result,
C-scan was able to produce a more accurate measurement of damage area compared
to optical method. Plate-like structure of FMLs samples showed higher maximum
impact loads when compared to beam-like structure. However, absorbed energy
remained higher in the beam-like structure. The post-impact damage area for platelike
structure showed linear increase while beam-like structure shows a plateauing at
approximately 1200mm2 due to the bending of the structure. Comparison also
showed that 20mm core thickness sample has the highest amount of absorbed energy
compared to 30 and 40mm. By increasing the temperature, maximum impact force
recorded has dropped under the same impact energy, being lowest at the 50°C and
highest at the -10°C. However, the energy absorbed for the sandwich structure
increased when the temperature was raised. The damage area at 25°C and 50°C
shows almost the same measurement of damage area, however, it is more likely that
the damage is more severe at 50°C due to the bending on the structure.
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