PSI - Issue 17

Kristýna Čápová et al. / Procedia Structural Integrity 17 (2019) 726 – 733 Kristýna Čápová et al. / Structural Integrity Procedia 00 (2019) 000 – 000

731

6

spectrometer to 1 °C would cause a change in wavelength indicated by the sensor to 0,03 nm. From the dependence measured by the optical fibre sensor with OrmocerT primary protection, it was found that changing the temperature of the spectrometer to 1 °C would cause a change in wavelength indicated by the sensor to 0,02 nm.

a

b

Fig. 9. Test 05 – dependence of the wavelength change of the sensor athermal_1512 on the internal temperature of spectrometer.

Fig. 5. Test 05 – dependence of the wavelength change of the sensor (a) athermal_1512 , (b) Ormocer on the internal temperature of spectrometer.

2.3. Second phase of testing in 2017

In the second phase of climatic testing, the tested samples consisted of wooden beams made of glued laminated timber (GLT) of strength class GL24 with cross-section of 80 x 60 mm and length of 1000 mm. The samples consisted of four spruce lamellae, each 15 mm thick. The optical fibres were inserted into a pre-formed groove 2 mm deep and 3 mm wide and then fixed with a superglue. This groove makes the fixing of the fibre easier and furthermore protects the fibre from the mechanical damage caused by the adjacent wood lamella during the lamination process. Each fibre was equipped with one FBG sensor in the middle of the span of timber beam in the axis of the element. The samples were produced in the Haas Fertigbau Chanovice, s.r.o. manufacturing plant. There were four samples of GLT beams with FBG sensors (GLT_FBG_1530, GLT_FBG_1540, GLT_FBG_1550, GLT_FBG_1560) and one sample of bare optical fibre with FBG sensor (FBG_1530_bare), all with the acrylic primary protection.

a

b

Fig. 6. (a) One of the test samples inside the climate chamber; (b) Strain measured by FBG sensors depending on the ambient temperature.