Fatigue damage assessment of UD CFRP composite laminates under spectrum loading using Acoustic Emission

M. Bourchak*, I. R. Farrow

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference Contribution (Conference Proceeding)


Notched UD CFRP composite material laminates were subjected to tensile static loading and tension-tension fatigue loading under variable amplitude loading (VAL). VAL tests were constructed so that the effect of Peak Stress, Trough Stress, Frequency and Cycle-Mix can be investigated. Online fatigue damage recording was carried out using Acoustic Emission (AE). Damaged specimens were also investigated using ultrasonic c-scanning and microscopy to reveal extent of damage and correlate with recorded AE data. AE monitoring revealed significant matrix failure as early as 50% of UTS during static tests. This indication dictated the selection of maximum stress level for fatigue loading which was no more than 75% of matrix failure stress. Results suggest that fatigue baseline data for composite materials should ideally be based on multiple block tests with a wide representation of frequency of occurrence of the main load levels within a load spectrum. Also, AE energy showed that cyclic fatigue damage is reasonably linear at low cyclic stress levels up to the first "effective failure" state. The implication is that the use of representative Cycle-Mix base data and the relatively linear damage accumulation trends up to initial effective failure state suggest that VAL fatigue life to this state could be achieved with a simple damage accumulation rule such as Palmgren-Miner's rule.

Original languageEnglish
Title of host publicationICCM International Conferences on Composite Materials
Publication statusPublished - 1 Dec 2011
Event18th International Conference on Composites Materials, ICCM 2011 - Jeju, Korea, Republic of
Duration: 21 Aug 201126 Aug 2011


Conference18th International Conference on Composites Materials, ICCM 2011
Country/TerritoryKorea, Republic of


  • Acoustic emission
  • Composite
  • Fatigue
  • Matrix cracking
  • Variable amplitude loading


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