Comprehending the Bending: A Comparison of Different Test Setups for Measuring the Out-of-Plane Flexural Rigidity of a UD Fabric

To simulate the forming process of a unidirectional (UD) glass fiber non-crimp fabric (NCF) for wind turbine blades, the fabric material needs to be characterized. In this way, input to the material model of the simulation can be generated. One important deformation to characterize is the out-of-plane bending. A number of test setups have been described in the literature but it is not clear which setup is more appropriate for the UD NCF under consideration. Therefore, five different out-of-plane bending test setups are compared and discussed, namely Peirce's cantilever test (with an inclined plane), the free-hanging cantilever test, a vertical cantilever test, a rotary rheometer bending test and a buckling test. For the latter an inverse modeling approach is developed. The test results shows that similar flexural rigidities can be computed from the different test setups but that some values are sensitive to the parameters used in the data processing techniques.