Evaluation of damage in composites by using Thermoelastic Stress
Analysis: a promising technique to assess the stiffness degradation
Abstract
The stiffness degradation represents one of the most interesting
phenomena used for describing the fatigue behaviour of composites. In
this regard, in literature, several works have been presented for
modelling the fatigue life by studying the stiffness degradation. A
critical aspect of modelling damage fatigue is represented by the
difficulties in simulating the whole behaviour of material and then in
describing the damage progression in all its stages. In addition, the
validation of models requires the measurement of stiffness variations by
means of experimental techniques. Above all for real components, the
difficulties in defying proper models are accompanied by the
difficulties in measuring stiffness degradation due to inapplicability
of classic experimental techniques. In this work, the stiffness
degradation of quasi-isotropic carbon-fibre-reinforced-polymer obtained
by automated fiber placement, has been assessed by means of
Thermoelastic Stress Analysis. The amplitude of temperature signal at
the mechanical frequency (thermoelastic signal) was considered as an
indicator of material degradation and compared to the data provided by
an extensometer. The correlation between thermoelastic and mechanical
data allowed to build a new experimental model for evaluating and
predicting material stiffness degradation by just using thermoelastic
data. The proposed approach seems to be very promising for stiffness
degradation assessment of real and complex mechanical components
subjected to actual loading conditions.