PSI - Issue 56

Tamas Krausz et al. / Procedia Structural Integrity 56 (2024) 71–77 Krausz/ Structural Integrity Procedia 00 (2019) 000–000

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Fig. 1. Aging of samples – 100 cycles of thermal load varying between -40 ° C and +85 ° C.

The fans mounted in both chambers ensured the high flow rate and even air distribution, and thus the homogenization of the temperature in the test space.

2.2. Tensile testing of non-aged samples at elevated temperatures For the tensile testing in the temperature range of 20 ° C - 80 ° C of the non-aged samples an Instron 8874 multiaxial test machine with hydraulic control has been used. The machine was equipped with an environmental chamber controlled by a resistance-wire heater and with a video-extensometer to capture the longitudinal and transversal displacements of four circular spots marked on the specimens. The tests were conducted with a constant loading rate of 50 mm/min. The temperature of the specimens inside the chamber has been monitored with a thermocouple to ensure the even distribution of the thermal load before the tensile tests. 2.3. Tensile testing of aged samples The tensile testing of the aged samples at room temperature and normal humidity conditions (20 ° C, 50%) has been conducted using a Zwick-Roell Z005 universal machine, equipped with a 5 kN load cell, in combination with a clip-on extensometer for strain recording, having a gauge length of 30 mm. Tests were performed with a constant cross head velocity of 2 mm/min. In addition to the clip-on extensometer, a Dantech Dynamics Digital Image Correlation system has also been utilized to capture the transversal deformations of the specimens during tension and hence to allow the calculation of the Poisson’s ratio of the thermally aged samples. 3. Results and discussions 3.1. The influence of uniform, constant heating It is generally known that the tensile response of polycarbonate, as of most polymeric materials, is highly dependent on strain rate and temperature, as confirmed by several studies (Cao et al., 2010, 2014).