Multi-scale simulation of low-speed impact loads on carbon fibre reinforced polymer (CFRP) panels

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Insinööritieteiden korkeakoulu | Master's thesis
Solid Mechanics
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Master's Programme in Mechanical Engineering (MEC)
87 + 5
In the field of advanced composites for high-technology applications, such as aerospace, the multi-scale modelling approach is of great importance. The novelty of this technique relies on the fact that it allows to study the macroscopic behaviour of the composite considering its microscopic characteristics. This is achieved by considering the composite as an interconnection of different length scales. The separation of length scales results into computational time-savings, as the macro-model does not need to include detail of the microstructure. Such method is used in the current thesis to model a CFRP panel and numerically simulate low-speed impact loads acting upon it. The multi-scale modelling tool used is the Multiscale Designer (MD) by Altair. This software computes homogenized material models using as inputs the material properties of the micro-constituents (fibre, matrix and interphase). The objective of the thesis is to understand the multiscale method that has been implemented in the MD software. Computational models are never completely accurate and they mismatch with experiments. The key is to understand why they do not give the same results, the reasons behind and how big or severe the deviations are. To do so, in this work different MD material models are generated for 1 ply and for the complete laminate. These are employed in two different FE macro-simulations corresponding to an indentation test and an impact test. Additionally, a manual material model based on laminate experimental constants is also used. The effects of the different material models on the indentation and impact FE-simulations are studied. The FE-results are compared to digital image correlation (DIC) data measured at the Laboratory of Materials Science of Tampere University, Finland. Eventually, the effect of the interphase on the macro-scale behaviour is evaluated. Finally, the results obtained through multi-scale are assessed to define the feasibility and applicability of the multi-scale approach in the composites modelling.
Romanoff, Jani
Thesis advisor
Kanerva, Mikko
Rodera García, Oscar
multi-scale modelling, simulation, composites, CFRP, impact loads, aerospace
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