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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6. Conclusions Based on the performed calculations and their analyzes, it can be concluded that: 1. Application of the ATH criterion for GFRP laminates [0/(±45)2/0] T of off-axis specimens cut at different angles θ = (0°, 30°, 45°, 60°, 90°) gave the worst compliance of the calculations with the results of experimental studies. On the other hand, the Norris criterion appeared to be the best. 2. The proposed criterion in the critical plane gave satisfactory results, the calculations of which are between those obtained using the ATH and Norris criteria. In this criterion, the coefficients of the influence of normal (transverse) and shear stresses in relation to the normal (axial) stress should be used. 3. Even though the Norris criterion may seem to be better than the criterion presented in this paper, defined in the critical plane, the newly proposed criterion gives new possibilities. It can be used to assess the fatigue life in complex operational or non-proportional load states. Perhaps after some modifications in the future, the criterion, defined in the critical plane, could give even more satisfying results, but already the results presented in this paper show that such an approach is a good solution for analyzing the complex stress state in the case of fatigue. References Awerbuch J., Hahn H.T., 1981. Off-axis fatigue of graphite/epoxy composite, Fatigue of Fibrous Composite Materials, STP 723, American Society for Testing and Materials, 243-273 Azzi V.D. Tsai, S.W., 1965. Anisotropic strength of Composites, Experimental Mechanics, vol.5 Chamis C.C., Sinclair J.H., 1976. 10° Off -axis tensile test for intralaminar shear characterization of fiber composites, NASA Technical Note D 8215 E 739-10 (2015) - Standard Practice for Statistical Analysis of Linear or Linearized Stress-Life (S-N) and Strain- Life (ε -N) Fatigue Gough, H. J., Pollard, H. V. 1935. Proceedings of the Inst. of mech. Engs., 131, 1-101 Grzelak J., Łagoda T., Macha E. , 1991. Spectral analysis of the criteria for multiaxial random fatigue, Mat. -wiss. u. Werkstofftech, 22, 85-98 Hill R., 1948. A theory of the yielding and plastic flow of anisotropic metals, Proceedings of the Royal Society, Series A, Vol. 193, 281-297 Kawai M., 2004. A phenomenological model for off-axis fatigue behavior of unidirectional polymer matrix composites under different stress ratios, Composites: Part A. 35, 955-963 Łagoda T., Kurek M., Głowacka K., 2020. A formulation of the criterion for multiaxial fatigue in terms of complex number as proposed by Macha, Int. J. Fatigue, vol.133 Łagoda K., Kurek A., Łagoda T., Błażejewski W., Osiecki T., Kroll L., 2019. Cracking of thick-walled fiber composites during bending tests, Theoretical and Applied Fracture Mechanics, vol. 101, 46-52 Michel S.A., Kieselbach R., Martens H.J., 2006. Fatigue strength of carbon fibre composites up to the gigacycle regime (gigacycle-composites), International Journal of Fatigue, 28, 261-270 Norris C.B., 1962. Strength of orthotropic materials subjected to combined stresses, Report no 1816, United States Department of Agriculture, Forest Products Laboratory, Madison, Wisconsin Philippidis T.P., Vassilopoulos A.P., 2002. Complex stress state effect on fatigue life of GRP laminates. Part I, Experimental, Int. J. Fatigue, vol.24, 813-823 Philippidis T.P., Vassilopoulos A.P., 2002. Complex stress state effect on fatigue life of GRP laminates. Part II, Theoretical formulation, Int. J. Fatigue. Vol.24, 825-830 Plumtree A., Cheng A.X., 1999. A fatigue damage parameter for off-axix unidirectional fibre-reinforced composites, International Journal of Fatigue, vol. 21, 849-856 Rotem A.,1997. Fatigue Failure of Multidirectional Laminate, AIAA Journal, vol. 17, 271-277 Sun C.T. at all., 1996. Comparative evaluation of failure analysis methods for composite laminates, NASA, DOT/FAA/AR-95/109 Walat K., Łagoda T., 2014. Lifetime of semi-ductile materials through the critical plane approach, Int. J. Fatigue, Vol.67, 73-77