LK
L.L. Krieg
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2 records found
1
Master thesis
(2025)
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L.L. Krieg, R.C. Alderliesten, R. Benedictus, S.J. Garcia Espallargas, S.F. Sartorio
The fatigue behaviour of fibre-reinforced polymer composites is typically characterised by costly and time-consuming stress–life testing. This thesis explores an alternative, energy-based approach by adapting complex modulus-based linear viscoelastic theory to describe hysteresis energy dissipation in continuous fibre composites under tensile–tensile fatigue. A modified framework introducing energy-based R–ratio corrections enabled consistent definitions of a viscoelastic loss factor, cyclic dissipation ratios and critical dissipated energy (CDE) across stress levels and load ratios. Analysis of both a literature reference and experimentally tested laminates showed that effective loss factors correlated with Dynamic Mechanical Analysis (DMA) results. The intersection with pristine DMA values provided reliable estimates of high-cycle fatigue strength (HCFS), consistent with existing infrared thermography methods. CDE was identified as a robust fatigue failure criterion, independent of R in the intermediate to high-cycle regime. These findings highlight the potential of energy-based methods to reduce testing requirements while improving predictive capability in composite fatigue.
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The fatigue behaviour of fibre-reinforced polymer composites is typically characterised by costly and time-consuming stress–life testing. This thesis explores an alternative, energy-based approach by adapting complex modulus-based linear viscoelastic theory to describe hysteresis energy dissipation in continuous fibre composites under tensile–tensile fatigue. A modified framework introducing energy-based R–ratio corrections enabled consistent definitions of a viscoelastic loss factor, cyclic dissipation ratios and critical dissipated energy (CDE) across stress levels and load ratios. Analysis of both a literature reference and experimentally tested laminates showed that effective loss factors correlated with Dynamic Mechanical Analysis (DMA) results. The intersection with pristine DMA values provided reliable estimates of high-cycle fatigue strength (HCFS), consistent with existing infrared thermography methods. CDE was identified as a robust fatigue failure criterion, independent of R in the intermediate to high-cycle regime. These findings highlight the potential of energy-based methods to reduce testing requirements while improving predictive capability in composite fatigue.
Bachelor thesis
(2022)
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C.H. Nieuwboer, M. Snoodijk, N. Prins, T. van Lith, Easwaar Easwaar Alagesen, L.L. Krieg, N. van Mierlo, M.S.B. Ali, W.L. Kruidenier, L.T. Lima Pereira, R.N.H.W. van Gent
As climate change becomes more and more apparent, it is necessary to find sustainable methods for future aviation. The battery industry is rapidly developing, allowing for batteries with more power density which make more electric aviation possible. As the average aerobatic flight is only 30-40 minutes, it is the perfect category to test these new electric methods. By using this information, the following mission need and project statement can be formulated.
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As climate change becomes more and more apparent, it is necessary to find sustainable methods for future aviation. The battery industry is rapidly developing, allowing for batteries with more power density which make more electric aviation possible. As the average aerobatic flight is only 30-40 minutes, it is the perfect category to test these new electric methods. By using this information, the following mission need and project statement can be formulated.