To study the resin flow and the permeability in fabric preforms during the liquid composite molding( LCM) process,influences of stitch and overlay placement styles on the internal flow behavior in-plane and transverse...To study the resin flow and the permeability in fabric preforms during the liquid composite molding( LCM) process,influences of stitch and overlay placement styles on the internal flow behavior in-plane and transverse were investigated. The permeability tests were carried using unidirectional and biaxial noncrimp carbon fabric( NCF) by linear capacitance sensors and ultrasound monitor system. The results indicate that the internal flow behavior and permeability in plane with different stitch and overlay placement styles are significantly different. When flow channels formed by stitches penetrate along the fiber direction,the permeability is high in one direction, which makes the in-plane principle permeabilities K_1 and K_2 significantly different. When there is an angle between the flow channel and fiber direction,the in-plane principle permeabilities on all directions are nearly the same and the flow process is close to isotropy. As to transverse permeability,the exist of flow channels on thickness influences it greatly and it is about 1-2 orders of magnitude lower in unidirectional fabric than that in biaxial NCF.展开更多
In order to investigate the draping behavior of non-crimp fabrics（NCFs）, two types of carbon NCFs with tricot-chain stitches or chain stitches were formed on a hemispherical mould via a stretch forming process. The ...In order to investigate the draping behavior of non-crimp fabrics（NCFs）, two types of carbon NCFs with tricot-chain stitches or chain stitches were formed on a hemispherical mould via a stretch forming process. The shear angle and forming defects of the fabrics were measured on the hemisphere, under different blank holder forces（BHFs）. The results showed that increasing BHF could enhance the shear angle slightly, reduce the asymmetry for the deformation of the fabrics, and change the main type of the process-induced defects. Besides, compression tests were performed on the corresponding composite components. By analyzing the change of fiber volume fraction and structural parameters of the textile reinforcements, the effects of draping behavior of NCFs on the mechanical performance of the composites were studied. The results reveal that draping process has distinguishable impacts on the mechanical properties of the final components, which is closely related to the stitching pattern of the NCFs.展开更多
基金National Natural Science Foundation of China(No.11472077)Shanghai Natural Science Foundation,China(No.13ZR1400500)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.2232015D3-01)Innovation Experiment Programs for University Students,China(Nos.201410255024,201510255118)
文摘To study the resin flow and the permeability in fabric preforms during the liquid composite molding( LCM) process,influences of stitch and overlay placement styles on the internal flow behavior in-plane and transverse were investigated. The permeability tests were carried using unidirectional and biaxial noncrimp carbon fabric( NCF) by linear capacitance sensors and ultrasound monitor system. The results indicate that the internal flow behavior and permeability in plane with different stitch and overlay placement styles are significantly different. When flow channels formed by stitches penetrate along the fiber direction,the permeability is high in one direction, which makes the in-plane principle permeabilities K_1 and K_2 significantly different. When there is an angle between the flow channel and fiber direction,the in-plane principle permeabilities on all directions are nearly the same and the flow process is close to isotropy. As to transverse permeability,the exist of flow channels on thickness influences it greatly and it is about 1-2 orders of magnitude lower in unidirectional fabric than that in biaxial NCF.
基金Funded by the National Natural Science Foundation of China(No.51203144)
文摘In order to investigate the draping behavior of non-crimp fabrics（NCFs）, two types of carbon NCFs with tricot-chain stitches or chain stitches were formed on a hemispherical mould via a stretch forming process. The shear angle and forming defects of the fabrics were measured on the hemisphere, under different blank holder forces（BHFs）. The results showed that increasing BHF could enhance the shear angle slightly, reduce the asymmetry for the deformation of the fabrics, and change the main type of the process-induced defects. Besides, compression tests were performed on the corresponding composite components. By analyzing the change of fiber volume fraction and structural parameters of the textile reinforcements, the effects of draping behavior of NCFs on the mechanical performance of the composites were studied. The results reveal that draping process has distinguishable impacts on the mechanical properties of the final components, which is closely related to the stitching pattern of the NCFs.
