Performance Analysis Of Layup-oriented Non-continuous Prepreg Composites

In this study,we design and prepare aligned discontinuous carbon prepreg composites by introducing slits containing four wide slits with 5mm?10mm?15mm?20mm at intervals of 40mm?80mm?120mm.Then,we select the tip deflection of a composite beam made of uncured plies consisting of continuous and discontinuous prepreg after 60 seconds as expryimental test for drapability,furthermore,we characterize and evaluate the differences of the drapability.Finally,the influences of the structural parameters on the tensile and bending mechanical properties of the laminate configuration of[45/0/-45/90]2s and the damage mechanisms for tensile and bending specimen are analyzed.The Digital Image Correlation(DIC)technique is used to record the surface full-field strain distribution during the axial tensile loading.The drapability test results show that its trend of tip deflection for continuous and discontinuous prepreg is the same,yet,the deformation of tip deflection for aligned discontinuous prepreg increases with the decrease of the slit width and slit interval.The deformation of tip deflection for 40mm-wide slits at the intervals of 20mm(referred to as 20-40mm)maximum 287.8mm which increasing 7.2%compared with the conventional prepreg,and its drapability is 1.072 for the maximum.Otherwise,the drapability of 5-120mm is 1.020 for the minimum.The axial tensile results show that tensile strength of aligned discontinuous prepreg decreases with the increase of slit width and the decrease of slit interval.The load of tensile test for 5-120mm aligned discontinuous composite laminates reaches the maximum value of 26284N,and the value of the load and the retention rate of tensile strength for its typical sample could reach 95%and 97%to conventional prepreg composites;At the same time,the retention rate of tensile strength the typical specimens is 64%for 20-40mm at least.The stress-strain curves of the typical samples in each group are near linear for all tensile specimens,and tensile modulus is almost the same.The average strain at failure of tensile specimenis1.05%?1.21%?1.36%?1.15%?1.09%?1.35%for the structural parameters of 5-40mm?5-80mm?5-120mm?10-40mm?10-80mm?10-120mm,when the average strain at failure of tensile specimen is 1.04%?1.13%?1.28%?0.98%?1.08%1.13%for the structural parameters of 15-40mm?15-80mm?15-120mm?20-40mm.20-80mm?20-120mm respectively.The surface full-field longitudinal contours present that the high strain area for conventional prepreg is arranged in a speckled pattern at the edge part,and the hign strain area with different extents exists in the edge of the slits and the bottom of the clamping part.The introduction of slits in the conventional prepreg changes the failure mode in tensile test,the interlaminar shear delamination resulting in the failure for continuous prepreg composites,while the failure mode is mainly fracture of fiber for aligned discontinuous prepreg composites.The bending test results show that flexural strength tends to increase with the decrease of slit width at the same slit intervals,and the flexural strength of the specimen reduced to a small extent.The bending load of typical specimen for 5-120mm reaches 265N,which is only 3 3%lower than continuous prepreg composite.The average flexural modulus is up to 94%of continuous prepreg composites laminates,while the flexural modulus is 81%at least to continuous prepreg composites bending specimen for the of 20-40mm structural parameters.Fracture of regularly appears in pressure surface bending specimen for aligned discontinuous prepreg composites.