Tatsuya Kosui

Effect of stitch and biaxial yarn types on tensile, bending, and impact properties of biaxial weft-knitted composites

Within the scope of experiments, the effect of stitch yarn type (aramid, glass and nylon), and biaxial, warp and weft, and yarn type (aramid and glass) was investigated in the biaxial weft-knitted (BWK) composites. Five different types of composite panel, which include fiber contents, such as glass-glass-glass, glass-glass nylon, glass glass aramid, aramid glass aramid and aramid aramid aramid were fabricated by hand lay-up method. After production of composite panels, tensile, three-point bending and three-point, bending impact tests were conducted on specimens. Microstructural characterization of tested materials was performed using a scanning electron microscope. This study showed that composites with BWK preforms consisting of fiber combinations, such as aramid-aramid-aramid, had higher tensile strength (in course direction), of aramid-glass-aramid had higher bending strength (in course direction), and of glass glass aramid had higher three-point bending impact properties (in course and wale directions) than other types of tested composite structures.

Effect of various knitting techniques on mechanical properties of biaxial weft-knitted thermoplastic composites:

Within the scope of experiments, five kinds of biaxial weft-knitted (BWK) fabrics with various knitting techniques (plain, interlock, tuck, tuck-miss, and interlock2) were used as reinforcement systems to fabricate thermoplastic composites with polypropylene (PP) resin yarn. Then, the final composite became BWK composites with various knitting types. The mechanical properties of composites were investigated by conducting tensile, three-point bending, and three-point bending impact tests on specimens. In all specimens, PP was commingled with glass yarn. Glass was used as reinforcement. Fiber volume fraction (Vf) of weft fibers of the interlock2 was the highest, and the length of straight part of loop shape was the longest in the interlock2 compared with the other four types of specimens. Because of the higher Vf of the BWK composites with the interlock2, tensile, three-point bending, and three-point bending impact properties of the interlock2 was higher than the other four types (plain, interlock, tuck, and tuck-miss) of composite structures.

Effect of stitch and biaxial yarn types on the impact properties of biaxial weft knitted textile composites

Abstract Within the scope of experiments, the effects of stitch yarn type, such as aramid, glass, and nylon, and biaxial, warp, and weft yarn type, such as aramid and glass, on biaxial weft knitted (BWK) composites were investigated. Five different types of composite panel, which include fiber contents, such as glass-glass-glass, glass-glass-nylon, glass-glass-aramid, aramid-glass-aramid, and aramid-aramid-aramid, were fabricated by hand lay-up method. After the production of composite panels, three-point bending impact and plate bending impact tests were conducted on the specimens. Microstructural characterization of the impact-tested materials was performed using an optical microscope. This study shows that composites with BWK preforms consisting of fiber combinations such as glass-glass-aramid had higher plate bending impact and three-point bending impact properties than the other four types of composite structure.

Effect of various loop lengths on mechanical properties of biaxial weft-knitted thermoplastic composites

Within the scope of experiments, five kinds of biaxial weft-knitted (BWK) fabrics with various loop lengths (8.0, 9.2, 10.5, 11.9, and 13.5 mm) were used as reinforcement systems to fabricate thermoplastic composites with polypropylene (PP) resin yarn. Then, the final composite became BWK composite with various loop lengths. The mechanical properties of the composites were investigated by conducting tensile, three-point bending, and three-point bending impact tests on specimens. In all specimens, PP was commingled with glass yarn. Glass was used as the reinforcement material. Fiber volume fraction of weft fibers with the 8.0 mm loop length was the highest compared with the other four types of specimens. Because of the higher volume fraction of the BWK composites with the 8.0 mm loop lengths, tensile, three-point bending, and three-point bending impact properties of the 8.0 mm loop were higher than the other four types (9.2, 10.5, 11.9, and 13.5 mm) of composite structures.

Effect of surface treatment and twisting on tensile and bending properties of aramid unidirectional composites

The present work concentrates on the effect of epoxy surface treatment and twisting on mechanical and interfacial properties of unidirectional (UD) fiber reinforced thermoplastic composites. The purpose of study is to find out whether the mechanical and interfacial properties of composites can be improved by surface treatment and twisting or not. In all specimens, PA 66 was commingled with aramid (AR) yarn. AR was used as reinforcement and PA 66 was used as resin yarn. The different weight percent of epoxy, such as 3, 6, and 9wt % and twisting such as 0, 20, 40, 60, 80, and 100 tpm, were applied on the commingled yarns. After fabrication of UD composites with commingled yarns, the mechanical properties of laminates were investigated by conducting tensile and three-point bending test. Consequently, the optimum twisting number and wt% of epoxy surface treatment was found. By increasing twisting until an optimum level, the tensile strength of fiber bundle as well as tensile and bending strength of UD composite increased. The interfacial properties of composites with various twisting levels did not change.

Modeling of tensile and bending properties of biaxial weft knitted composites

Abstract Within the scope of experiments, the effect of aramid and glass yarns as stitch and biaxial (warp and weft) yarns in the biaxial weft knitted (BWK) composite was compared. After production of four types of composite panel using the hand lay-up method, the tensile and bending properties of the BWK composites were investigated both experimentally and numerically. The composite with the glass stitch and biaxial yarns exhibited higher tensile and bending properties than did the composite with the aramid stitch and biaxial yarns. The good agreement between the experimental results and the numerical results validated the applicability of the finite-element method for the BWK composites. The laminate beam theory was utilized as another modeling method for calculation of the bending modulus.

Mechanical properties of biaxial weft-knitted and cross-ply thermoplastic composites

Within the scope of experiments, two kinds of biaxial weft-knitted (BWK) fabrics with aramid (AR) and polyamide (PA) 66 stitch fibers were used as reinforcement systems to fabricate thermoplastic composites with PA66 resin yarn. Then, the final composite became BWK with AR stitch yarn and cross-ply. The mechanical properties of composites were investigated by conducting tensile and three-point bending impact tests on specimens. In all specimens, PA66 was commingled with AR yarn. AR was used as reinforcement. In preliminary studies, AR unidirectional composites with AR/PA66 commingled fibers and with various twisting angles were produced and appropriate twisting angle was found out by conducting tensile test on specimens. Due to the random multiple cracks that changed the fracture behavior of BWK composites with AR stitch, the tensile properties of the BWK composites with AR stitch became lower compared with the cross-ply. However, the three-point bending impact properties of the BWK composites with AR stitch fiber were higher compared with the cross-ply.

Tensile and bending properties of biaxial weft-knitted and cross-ply thermoplastic composites

In this study, within the scope of experiments, two kinds of biaxial weft-knitted (BWK) fabrics with aramid (AR) and polyamide 66 (PA66) stitch fibers were used as reinforcement systems to fabricate thermoplastic composites with PA66 resin yarn. Then final composite became BWK with AR stitch yarn and cross-ply. The mechanical properties of composites were investigated by conducting tensile and three-point bending tests on specimens. In all specimens, PA66 was commingled with AR yarn. AR was used as reinforcement. In preliminary studies, AR unidirectional composites with AR/PA66 commingled fibers and with various twisting angles were produced and appropriate twisting angle was found by conducting tensile and three-point bending impact tests on specimens. Because of the higher volume fraction of the cross-ply composites, tensile and three-point bending properties of the cross-ply composite structures had higher than the BWK composites with the AR stitch yarn.