Assessment of fatigue damage evolution in woven composite materials using infra-red techniques

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Description/Abstract

Thermoelastic stress analysis (TSA) is used to study the growth of fatigue damage in single and two
ply, 2 x 2 twill woven composite materials. Test specimens were subjected to a uniaxial tensile cyclic
loading with maximum stresses of 10, 15 and 20% of the ultimate failure stress. The development of
fatigue damage locally within the weft yarns is monitored using high resolution TSA. The specimens
were subsequently inspected using optical microscopy to evaluate the location and extent of cracks.
Cracks were found in the weft fibres, running transverse to the loading direction. It is demonstrated that
the lighter weight fabric is more resilient to damage progression. A signature pattern is identified in the
TSA phase data that indicates the onset and presence of fatigue damage in the composite material.