PSI - Issue 57

J. Torggler et al. / Procedia Structural Integrity 57 (2024) 152–160 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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In the first step, the damage is analysed optically, then for selected samples also by means of micro computed tomography (µCT). The resulting voxel size in the µCT analysis was 35 µm, which is limited by the dimensions of the sample. Already from the outside, certain irregularities can be seen on the surface, for example damage at the edge and near the clamping of the specimen. Figure 4 shows an example of a damage analysis of the sample after the test. The damage that has occurred can be examined even more closely by means of µCT analysis. Different types of damage can be seen in the different views. Dominant in the section XY is the damage in the middle of the sample, where an interfibre breakage is visible. In addition, a detachment of the inner layers from each other (delamination) is clearly visible in the XZ section views two to four. Broken and pulled out fibres can be seen in the centre of the fractured surface as well as at the edge. The sequence of the damage cannot be fully reconstructed here, for this purpose, µCT scans will be carried out at different number of load-cycles during fatigue testing in the future. Several literature sources indicate that the damage (e.g. fatigue cracks) in the composite originates from the interface between the cord and the matrix, such as Pidaparti and May (2001), Eitzen et al. (2018).

Figure 4: Fracture pattern analysis with the help of µCT analysis, section XY (left) and sections XZ (right)

The evaluation and damage analysis were applied to different samples with the different material confections. In the following sections, the results and comparisons are discussed.