Issue 42

R. Pawliczek et alii, Frattura ed Integrità Strutturale, 42 (2017) 30-39; DOI: 10.3221/IGF-ESIS.42.04 35 a) b) Figure 4 : Block loading applied in fatigue tests: a) for increasing mean load value, b) for decreasing mean load value. The view of the fatigue tests stand MZGS100 is presented in Fig. 5a. The stand allows realizing tests under cyclic bending with mean load value, which is applied by spring actuator. The applied loads and observed deformations (strains) of the specimens were measured during the tests. The strain bridge NI USB9237 and the author’s software (Fig. 5b) were used. It was possible to observe on-line the time courses of loading (amplitude and mean value of the bending moment) and strains and additionally moment-strain curve was displayed. a) b) Figure 5 : Fatigue tests: a) the view of the fatigue tests stand, b) software’s user interface. An example time histories of bending moment and corresponding strains are shown in Fig. 6. Figure 6 : Registered moment and strains history. n 1 n 2 n 3 N b N  1 3 2 n 1 n 2 n 3 N b N  3 1 2 0 0.02 0.04 0.06 0.08 0.1 t, s -25 -20 -15 -10 -5 0 5 10 15 20 -0.004 -0.002 0 0.002 0.004  M N.m