Viscoelastic material models for nanocomposites : Simulation, characterization and anisotropic analysis
Ramanan, Pradeep (2022)
2022
Master's Programme in Materials Science and Engineering
Tekniikan ja luonnontieteiden tiedekunta - Faculty of Engineering and Natural Sciences
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Hyväksymispäivämäärä
2022-03-31
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-202203032285
https://urn.fi/URN:NBN:fi:tuni-202203032285
Tiivistelmä
Environment friendly nanocomposites are an active field of research and development giving rise to new possible materials with enhanced properties. These physical properties are not limited to mechanical properties and also extend to thermal, electrical and even more categories. The mechanical properties of such materials are enhanced since they are being influenced by nanoscale dimension fillers. Accurate determination of material constants for these are dimension scale dependent. The homogeneity of the filler material present in the nanocomposite matrix is also another influential factor. Different characterization and testing techniques exists for estimating or determining the values for material constants. Tensile tests help to evaluate macroscopic scale values while nanoindentation helps to evaluate microscopic effects. Due to nanocomposite materials exhibiting viscoelastic behaviour, it is essential to include them in the micromechanics material study approach.
This thesis focuses on the elastic and viscoelastic material response of two nanocomposites, CNT-NFC (Carbon Nanotube – Nano Fibrillated Cellulose) and GO-GP (Graphene Oxide – Gelatine Powder). Based on these, a material model is built and a nanoindentation simulation is conducted whereby the results are compared to the experimental results. The simulation results take the value of material constants determined through DMA (Dynamic Mechanical Analysis) while experimental results consist of values obtained from nanoindentation. DMA is especially useful to study and estimate the viscoelastic properties of viscoelastic solids.
Simulating, observing and comparing the material responses by adding them individually using a software package named Abaqus, the viscoelastic material model was found to move simulation results closer to experimental results. Sensitivity analysis helped to deduce the type of possible anisotropic material behaviour for the materials of interest in this study. The influence of frictional effects proved to be a significant contributor in the overall material model study. By finding out the range of agreement provided by the material model, certain statements of thought were put forward. These could be helpful if the study is to be carried on further to probe the material in much more detail.
This thesis focuses on the elastic and viscoelastic material response of two nanocomposites, CNT-NFC (Carbon Nanotube – Nano Fibrillated Cellulose) and GO-GP (Graphene Oxide – Gelatine Powder). Based on these, a material model is built and a nanoindentation simulation is conducted whereby the results are compared to the experimental results. The simulation results take the value of material constants determined through DMA (Dynamic Mechanical Analysis) while experimental results consist of values obtained from nanoindentation. DMA is especially useful to study and estimate the viscoelastic properties of viscoelastic solids.
Simulating, observing and comparing the material responses by adding them individually using a software package named Abaqus, the viscoelastic material model was found to move simulation results closer to experimental results. Sensitivity analysis helped to deduce the type of possible anisotropic material behaviour for the materials of interest in this study. The influence of frictional effects proved to be a significant contributor in the overall material model study. By finding out the range of agreement provided by the material model, certain statements of thought were put forward. These could be helpful if the study is to be carried on further to probe the material in much more detail.