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. 2022 May 26;15(11):3787.
doi: 10.3390/ma15113787.

CFRP Fatigue Damage Detection by Thermal Methods

Marta De Giorgi  1 , Riccardo Nobile  1 , Fania Palano  2
Affiliations

CFRP Fatigue Damage Detection by Thermal Methods

Marta De Giorgi et al. Materials (Basel). .

Abstract

In this work, the fatigue damage of CFRP uniaxial composite specimens were studied using thermal methods to determine the fatigue behavior. The aim was to evaluate the fatigue damage as a function of the number of cycles. Consequently, the damage process was studied in terms of a global indicator, considering the stiffness decay, and in terms of local parameters, considering the evolution of temperature maps acquired during the fatigue tests. A direct correlation between the damage index, corresponding to 90% of the fatigue life, and the temperature variation of the most stressed area was found. Another parameter taken into consideration was the heating rate during the application of the first thousands cycles. This parameter was proportional to the stress amplitude, making it a useful parameter since it refers to the initial part of the specimen fatigue life.

Keywords: composites; damage; fatigue; thermal methods.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Geometry of the tested specimens.
Figure 2
Figure 2
Wöhler curve of the unidirectional composite.
Figure 3
Figure 3
Stiffness trend as a function of the normalized number of cycles.
Figure 4
Figure 4
Trend of normalized stiffness for the various load levels applied.
Figure 5
Figure 5
Calculation of the stiffness percentage variation ΔR%.
Figure 6
Figure 6
Evolution of the damage index: (a) global; (b) detail of the first cycles.
Figure 7
Figure 7
Thermograms at different loading cycles for specimen 1b.
Figure 8
Figure 8
Thermograms at different loading cycles for specimen 14b.
Figure 9
Figure 9
Thermograms at different loading cycles for specimen 8b.
Figure 10
Figure 10
Trend of the temperature increase ΔT as a function of the number of cycles.
Figure 11
Figure 11
Spatial trend of the thermal profile at different load cycles: (a) specimen 1b; (b) specimen 14b.
Figure 12
Figure 12
Relationship between the maximum temperature increase and the damage index at 90% of the fatigue life.
See this image and copyright information in PMC

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