On the thermomechanical behavior of model composites using digital image correlation
Resumo
In composite systems with incompatibility between the coefficients of thermal
expansion (CTE) of their phases, stresses can lead to cracking of the material
during a temperature variation. Analytical, numerical and experimental studies
on the subject have been carried out. Experimentally, this topic is difficult to approach,
since observing and measuring the effects of temperature variation in
composite systems is not a trivial task. With the development and improvement
of field measurement techniques such as Digital Image Correlation (DIC), a new
approach is proposed in combination with the use of model composites. In the
present study, mechanical and thermal properties of model composites phases
composed of alumina and colloidal silica matrices with cylindrical inclusions of
brass or zirconia were evaluated, and temperature variation experiments aided
by DIC were carried out to obtain experimental displacement and strain fields.
The model composites temperature variations were conducted up to 300, 600 or
900 ○C depending on the systems’s response up to that temperature. Such experiments
allow the visualization of the model composites cracking, which can be
quantified in terms of crack initiation and evolution. The quantification of cracking
was done from the calculation of an inelastic strain field. Obtaining this field of
both opposite faces of the tested systems and quantifying its cracking provides
data for comparison with analytical and numerical modeling of cracking phenomena
due to CTE incompatibility of such systems, results that do not exist in the
literature. Thus, the data produced allows the modeling of this phenomenon to be
carried out for the proposed composite systems, using the evaluated properties
and having field information and parameterized cracking parameters for comparison.
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