Finite element predictions of in‐situ 3D x‐ray CT determined compression failure of uni‐directional composites
Topic(s) : Special Sessions
Co-authors :
Pinelopi MAGEIRA (DENMARK), Ole V. FERGUSON , Konstantinos POULIOS , Katherine NELMS (UNITED KINGDOM), Philip WITHERS (UNITED KINGDOM), Lars PILGAARD MIKKELSEN (DENMARK)Abstract :
The use of pultruded composites for wind turbines' blades made its noteworthy breakthrough recently. The pultrusion manufacturing process enhances the fiber straightness and ensures a consistent material quality. However, manufacturing defects can still occur; a possibility increased by the fact that CFRPs are inherently sensitive to fiber misalignments during compressive loading, leading to the severe reduction of the blade's strength, degrading the material's and thus the structure's behavior.
This work develops a finite element model, coupled with 3D x‐ray CT scanned data, which will enable accurate prediction of the mechanical properties and the identification of critical defects areas in unidirectional carbon fibre composites. Something which potentially can lead to improved strength and reliability of wind turbine composite blades. Emphasis is on simulating and predicting kink-band formation resulting from fiber misalignment during compressive loading, causing severe mechanical property degradation. The numerical model will predict mechanical properties, revealing the impact of specific defects on the structure. This eliminates critical defects, ensuring the strength of pultruded profiles of composite wind turbine blades aligns with expectations.
To achieve this, data from unidirectional composite samples are used (Cristex ZOLTEK 50K non-crimp carbon fibre, Huntsman Araldite LY 564 epoxy resin). To trigger the kink band formation during the compression, a notch of 100-150 μm depth was cut on each sample’s side. Compression of the samples took place at a speed of 0.3 mm/minute. 3D x‐ray CT data are gathered, analyzed and coupled with the structure tensor method, allowing for mapping the actual spatial fiber orientation on the finite element model. The FEM model will be loaded in compression and thereby predicting the kink‐band formation. Two different modeling approaches will be explored, both based on an elastic-plastic non-linear incremental fiber matrix homogenized composite formulation and including fiber bending effects in one of them. The FEM prediction model aims to reproduce the in-situ observed compressive failure mechanism observed in Nelms (2023).
Acknowledgement
This study was funded by EU Horizon MSCA 2021 DN Reliance: REaL-tIme characterization of ANisotropic Carbon-based tEchnological fibres, films and composites.
Reference
Nelms, K., Paul, P. P., Wowogno, A., Chen, Y., Lukic, B., Rack, A., Chandarana, N., & Withers, P. J. (2023). Effects of fibre orientation on compression micromechanics in CFRP investigation by computed tomography. 23rd International Conference on Composite Materials (ICCM23).
This work develops a finite element model, coupled with 3D x‐ray CT scanned data, which will enable accurate prediction of the mechanical properties and the identification of critical defects areas in unidirectional carbon fibre composites. Something which potentially can lead to improved strength and reliability of wind turbine composite blades. Emphasis is on simulating and predicting kink-band formation resulting from fiber misalignment during compressive loading, causing severe mechanical property degradation. The numerical model will predict mechanical properties, revealing the impact of specific defects on the structure. This eliminates critical defects, ensuring the strength of pultruded profiles of composite wind turbine blades aligns with expectations.
To achieve this, data from unidirectional composite samples are used (Cristex ZOLTEK 50K non-crimp carbon fibre, Huntsman Araldite LY 564 epoxy resin). To trigger the kink band formation during the compression, a notch of 100-150 μm depth was cut on each sample’s side. Compression of the samples took place at a speed of 0.3 mm/minute. 3D x‐ray CT data are gathered, analyzed and coupled with the structure tensor method, allowing for mapping the actual spatial fiber orientation on the finite element model. The FEM model will be loaded in compression and thereby predicting the kink‐band formation. Two different modeling approaches will be explored, both based on an elastic-plastic non-linear incremental fiber matrix homogenized composite formulation and including fiber bending effects in one of them. The FEM prediction model aims to reproduce the in-situ observed compressive failure mechanism observed in Nelms (2023).
Acknowledgement
This study was funded by EU Horizon MSCA 2021 DN Reliance: REaL-tIme characterization of ANisotropic Carbon-based tEchnological fibres, films and composites.
Reference
Nelms, K., Paul, P. P., Wowogno, A., Chen, Y., Lukic, B., Rack, A., Chandarana, N., & Withers, P. J. (2023). Effects of fibre orientation on compression micromechanics in CFRP investigation by computed tomography. 23rd International Conference on Composite Materials (ICCM23).