Research On Preparation Process And Mechanical Properties Of K-cor Sandwich Structure

K-Cor sandwich structure is expected as a novel composite material which reinforced withZ-pins on blank foam. Compared to traditional X-cor and honeycomb structure, it has more potentialapplications due to its superior mechanical properties. Up to now, there is little paper reported at homeand abroad about its fabrication process and mechanical properties. According to literatures review,this paper presented an experimental investigation on the pultrusion parameters and bending processof the partially-cured Z-pins. In order to determine the cure degree of Z-pins, differential scanningcalorimetry (DSC) technique combinded with the observation of implanted Z-pins in K-cor structureby optical microscope (OM) are employed. At last K-cor structure is successfully fabricated.In this study, the climbing drum peel test is firstly applied for K-cor, X-cor and blank foam coreto compare their bonding strength between Z-pins and face sheets. Experimental result shows thatpeeling strength of K-cor is much larger than that of X-cor and blank foam core. Subsquently, theinfluence of different angles and densities of Z-pins on out-of-plane tension, compression and sheartests are coampared. Results obtained from above tests indicate that their strength and modulusincrease with increasing densities under the same diameters and angles of Z-pins. The strengtheningmechanism is mainly resulted from cross-linking reaction between partially-cured Z-pins and facesheets. Under the same conditions of densities and diameters of Z-pins, the strength and modulus ofout-of-plane tensile and compression have got increased with increasing Z-pin’s angles, while shearstrength and modulus get decreased. The increased strength of compression is mainly attribuated tothe resistance of deformation capacity of Z-pins resuted from increasing value of implanted angles.According to the observation and analysis of failure modes, mechanical properties are mainlydepend upon their bonding strength between Z-pins and face sheets. As for X-cor, there is only1mmlength of cured Z-pins beyond the foam that will take slightly mechanical link between foam and facesheets; while for K-cor, partially cured Z-pins with5mm length outside the foam to make the fullcross-linking reaction between foam and face sheets. So K-cor has a large strength.Furthermore, BMI K-cor structures are also prepared and make a comparison with X-cor and theblank foam core by the out-of-plane tension and compression measuremnts. Experimental resultsexhibit that both of strength and modulus are clearly greater of K-cor structure compared to traditionalX-cor and blank foam core under the same conditions of implant parameters of Z-pins.