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Incorporation of Fiber Bragg Sensors for Shape Memory Polyurethanes Characterization

Alberto, N. ; Fonseca, M. A. Fonseca ; Neto, V. Neto ; Nogueira, R.N. ; Correia, M. Correia ; Moreira, R. Moreira

Sensors Vol. 17, Nº 11, pp. 2600 - 2600, November, 2017.

ISSN (print): 1424-3210
ISSN (online): 1424-8220

Journal Impact Factor: 2,033 (in 2015)

Digital Object Identifier: 10.3390/s17112600

Shape memory polyurethanes (SMPUs) are thermally activated shape memory materials,
which can be used as actuators or sensors in applications including aerospace, aeronautics,
automobiles or the biomedical industry. The accurate characterization of the memory effect of these
materials is therefore mandatory for the technology’s success. The shape memory characterization
is normally accomplished using mechanical testing coupled with a heat source, where a detailed
knowledge of the heat cycle and its influence on the material properties is paramount but difficult
to monitor. In this work, fiber Bragg grating (FBG) sensors were embedded into SMPU samples
aiming to study and characterize its shape memory effect. The samples were obtained by injection
molding, and the entire processing cycle was successfully monitored, providing a process global
quality signature. Moreover, the integrity and functionality of the FBG sensors were maintained
during and after the embedding process, demonstrating the feasibility of the technology chosen for
the purpose envisaged. The results of the shape memory effect characterization demonstrate a good
correlation between the reflected FBG peak with the temperature and induced strain, proving that
this technology is suitable for this particular application.