PSI - Issue 19

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Marc J.W. Kanters et al. / Procedia Structural Integrity 19 (2019) 698–710 Marc Kanters et al./ Structural Integrity Procedia 00 (2019) 000–000

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Improvement of the stress concentration correction method is a topic of further investigation. The framework highlighted in this paper is now ready and available in Digimat and material cards are ready and available for use. The enhanced model will correct for anisotropy, local stress ratio, and stress gradients and can be evaluated with the Digimat RP fatigue post-processer. 5. Conclusions This work demonstrates that to accurately predict fatigue lifetime of short fiber reinforced plastics it is essential to consider the effect of local stress, local fiber orientation in high detail, stress concentrations, and local stress ratio. By step-by-step adding complexity, it is shown that where commercial tools allow proper modelling of anisotropy and load ratio dependence, the compensation for local stress concentrations can introduce significant error and needs improvement. However, it is shown that by using a model that is consistent for a large range of microstructures, load ratios, and stress concentrations, the accuracy that one can expect is approximately within a factor 5 - 30, demonstrated for a wide range of load ratios. References Askes, H., Livieri, P., Susmel, L., Taylor, D., Tovo, R., 2013. Intrinsic material length, Theory of Critical Distances and Gradient Mechanics: analogies and differences in processing linear-elastic crack tip stress fields. Fatigue and Fracture of Engineering Materials and Structures, 36, 39-55. DeMonte, M., Moosbrugger, E., Quaresimin, M., 2010. Influence of temperature and thickness on the off-axis behaviour of short glass fibre reinforced polyamide 6.6 – Quasi-static loading. Composites: Part A, 41, 859-871. Dogri, I. Friebel, C., 2005. Effective elasto-plastic properties of inclusion-reinforced composites. Study of shape, orientation and cyclic response. Mechanics of Materials, 37, 46-68. Dogri, I. Tinel, L., 2005. Micromechanical modeling and computation of elasto-plastic materials reinforced with distribution–orientation fibers. International Journal of Plasticity, 21, 1919-1940. Elringklinger, 2017. Lightweight plastic components. For cars and commercial vehicles, brochure. e-Xstream engineering, 2019. Digimat documentation Release 2019.0. http://www.e-xstream.com/ Gedde, U.W., Viebke, J., Leijström, H., Ifwarson, M., 1994. Long-term properties of hot-water polyolefin pipes - a review. Polymer Engineering Science, 34, 1773-1787. Janssen, R.P.M., Govaert, L.E., Meijer, H.E.H., 2008. An analytical method to predict fatigue life of thermoplastics in uniaxial loading: sensitivity to wave type, frequency, and stress amplitude. Macromolecules, 41, 2531-2540. Kanters, M.J.W., Kurokawa, T, Govaert, L.E., 2016. Competition between plasticity-controlled and crack-growth controlled failure in static and cyclic fatigue of thermoplastic polymer system. Polymer Testing, 50, 2531-2540. Kanters, M.J.W., Engels, T.A.P., van Erp, T.B., Govaert, L.E., 2018. Predicting long-term crack growth dominated static fatigue based on short term cyclic testing. International Journal of Fatigue, 12, 318-327. Lang, R.W., Stern, A., Doerner, G., 1997. Applicability and limitations of current lifetime prediction models for thermoplastics pipes under internal pressure. Die Angewandte Makromolekulare Chemie, 247, 131-145. Molski, K., Glinka, G., 1981. Method of Elastic-Plastic Stress and Strain Calculation at a Notch Root. Materials Science and Engineering, 50, 93 100. Mortazavian, S., Fatemi, A., 2016. Effects of mean stress and stress concentration on fatigue behavior of short fiber reinforced polymer composites. Fatigue & Fracture of Engineering Materials & Structures, 39, 149-166. Neuber, H., 1961. Theory of Stress Concentration for Shear-Strained Prismatical Bodies With Arbitrary Nonlinear Stress-Strain Law. Journal of Applied Mechanics, 28, 544-550. Primetzhofer, A., Stadler, G., Pinter, G., Grün, F., 2019. Lifetime assessment of anisotropic materials by the example short fibre reinforced plastic. International Journal of Fatigue, 120, 294-302. Sonsino, C.M., Moosbrugger, E., 2008. Fatigue design of highly loaded short-glass-fibre reinforced polyamide parts in engine compartments. International Journal of Fatigue, 30, 1279-1288. Susmel, L., 2008. The theory of critical distances: a review of its applications in fatigue. Engineering Fracture Mechanics, 75, 1706-1724. Weiss, M., Tuncay, V., Richter, S., Broz, J., 2017. Umfassende Simulation und vernetzte Intelligenz im Thermomanagement. MTZ - Motortechnische Zeitschrift, 78, 42-49. Winter, D., 2016. Survey: CAFE Rules Likely to Get Tougher, Not Easier. WardsAuto. Winter, D., 2017. Auto Engineers See Future CAFE Rules Easing. WardsAuto.