PSI - Issue 41

Karolina Głowacka et al. / Procedia Structural Integrity 41 (2022) 232 – 240 Głowacka K., Łagoda T./ Structural Integrity Procedia 00 ( 2019) 000 – 000

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Table 2. Set of the angles of the critical plane depending on the cut angles. , ° , ° 0 0 30 41.22 45 54.80 60 66.84 90 90

Figure 2 shows this summary in a visual form. The analysis of the scheme shows that it is not a linear relationship, but an exponential one that can be described by the formula in the form = 3.682 ∙ 0.709

(12)

Fig. 2. Dependence of the angle of the critical plane’s position on the ang le of excision of the specimens.

5. Verification of multi-axial fatigue criteria for composite laminate In order to verify the correctness and applicability of the strength criteria, calculations of the equivalent amplitude were made on the basis of the proposed ATH (3), Norris (4) criteria, as well as the new one proposed in the critical plane (11) and compared with the experimental fatigue life. The fatigue characteristic determined for the fatigue tests with the specimen cutting direction consistent with 0° was adopted as a reference point. This verification is illustrated in Figures 3-4 for each analyzed criterion, respectively. In the figures, a straight line marks the reference curve determined on the basis of experimental tests. The remaining points were determined on the basis of calculations.