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Item type:Publication, Access status: with files , Comparison of analytical approaches predicting the compressive strength of fibre reinforced polymers(Multidisciplinary Digital Publishing Institute (MDPI), 2018-12-11); ; ; ; Common analytical models to predict the unidirectional compressive strength of fibre reinforced polymers are analysed in terms of their accuracy. Several tests were performed to determine parameters for the models and the compressive strength of carbon fibre reinforced polymer (CFRP) and glass fibre reinforced polymer (GFRP). The analytical models are validated for composites with glass and carbon fibres by using the same epoxy matrix system in order to examine whether different fibre types are taken into account. The variation in fibre diameter is smaller for CFRP. The experimental results show that CFRP has about 50% higher compressive strength than GFRP. The models exhibit significantly different results. In general, the analytical models are more precise for CFRP. Only one fibre kinking model’s prediction is in good agreement with the experimental results. This is in contrast to previous findings, where a combined modes model achieves the best prediction accuracy. However, in the original form, the combined modes model is not able to predict the compressive strength for GFRP and was adapted to address this issue. The fibre volume fraction is found to determine the dominating failure mechanisms under compression and thus has a high influence on the prediction accuracy of the various models.Publicationtype: Journal ArticleScopus© Citations 11 349 343 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Influence of 90°-layer thickness on damage initiation and propagation in CFRP cross-ply laminatesThe influence of layer thickness on failure initiation and damage propagation as matrix cracks in the 90°-layers of cross-ply laminates is investigated experimentally and simulated by using FEM. Decreasing the 90°-layer thickness leads to a shift of damage initiation to higher loads. The crack density and the shape of inter fibre failure also depend on the layer thickness. With increasing 90°-layer thickness, the total amount of cracks decreases, whereas the amount of cracks running through the layer thickness and through the whole specimen width increases. Cracks exhibit a faster growth rate and larger crack opening with increasing layer thickness. This case is more severe for initiating delaminations. A reduction of ply thickness in cross-ply laminates increases the resistance against inter-fibre-fracture and thus offer great potential for increased fatigue lifetime.Publicationtype: Conference Paper52 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Influence of ply thickness on the fibre matrix debonding(2015-07); ; ; In this work, the influence of ply thickness in the 90° layer in cross-ply laminates on the initiation of fibre matrix debonding and inter-fibre-fracture under tensile loads is investigated experimentally by using model composites as well as in a FEM simulation. Decreasing the ply thickness leads to a shift of the onset of inter-fibre-fracture to higher loads. The failure propagation at higher loads is less severe with decreasing layer thickness. Explanations for this behaviour like the probability of a critical defect in the reduced volume or the in-situ effect are discussed. The FEM model is able to represent the ply thickness effect and simulation results are qualitatively in good agreement with the experiments. In the simulation, first fibre-matrix-debonding was found at higher global strain and matrix cracks were more but less severe for thinner plies, whereas an earlier damage onset and fewer cracks, running through the whole layer thickness are found for thicker layers. A reduction of ply thickness in cross-ply laminates increases the resistance against inter-fibre-fracture and failure propagation.Publicationtype: Conference Paper27