The effect of fiber waviness as manufacturing defect on the fatigue life of CFRP materials
Sprache des Vortragstitels:
20th International Conference on Composite Materials
Sprache des Tagungstitel:
Manufacturing defects in carbon fibre reinforced plastic parts are a balancing act, particularly between safety and cost. Common defects in carbon fibre reinforced plastic parts are voids, porosity, in-plane and out-of-plane layer waviness, inclusions, and even folds of layers. In this work, an automotive non-crimp fabric showing out-of-plane fibre waviness, as it may appear during a high pressure resin transfer moulding process, is investigated. The effect of the manufacturing defect on the compressive static strength and fatigue life of a thin laminate is assessed, considering the influence of different cyclic loading cases.
Static and fatigue tests are performed in order to observe the triggered damage modes, the sequence and interaction of different modes, and the propagation of damage up to the final failure of the sample. The aim of the experimental study is to provide a deep understanding of damage initiation and progression due to the presence of the manufacturing defects.
Prediction of the effects of the defect on the fatigue damage initiation and progression is done, based on detailed meso-scale parametric static FE simulation, supported by the use of non-destructive testing (ultrasonic and microscopy analysis) of the composite material configuration. Correlation between the numerical results and the experimental data is done, in order to validate the experiments, and to assess the predictive capabilities of the numerical modelling.
A manufacturing defect metric is established for the case under investigation and quantitative assessment of the influence of this metric on the compression fatigue life of the material is performed, such that the proposed metric can be used for defining acceptance/rejection criteria for composite parts containing manufacturing defects.