Mechanical degradation of single fibres

    Beskrivelse

    The purpose of the project is to investigate degradation of single, free fibres under cyclic loading condition. The design and development of the experimental set-up that allows a single fibre to be cyclically loaded under the Raman microscope has been completed. The cyclic force applied to the fibre, and the fibre displacements are carefully measured during fatigue period. Significant difficulties have been encountered with a reliable mapping of Raman spectra along the fibre axis during fatigue hold times. The reason for that was an induced deformation and eventual fibre displacement with respect its starting position at the Raman focal plane. This problem has been resolved with the advent of automatic focusing device, which eliminates operator subjectivity of finding a focal plane for measurements at each hold time during fatigue testing. The pilot measurements of low-cycle fatigue of polypropylene fibres show significant changes in the fibre internal structure expressed in terms of changes in the stiffness and the static stress-strain relation. A series of low-cycle experiments will be carried out simultaneously recording the Raman spectra point-wise as well as scanning a fibre along its gauge length during a hold time. A collection of Raman spectra during a long-term loading should provide the information about microstructural changes taking place within a fibre. This information will be further used to build a lattice model of the fibre in order to predict progressive degradation (or change) of mechanical properties. Additional X-ray diffraction measurements are planned to disclose changes in the fibre microstructure, which are hidden in the Raman spectra. (Thomas Thomsen, Ryszard Pyrz)
    StatusIgangværende
    Effektiv start/slut dato19/05/2010 → …