Thermo-Lateral Compression Forming and Bending Properties of Pultruded CF/PEEK Rods for Grid Structure
Topic(s) : Manufacturing
Co-authors :
Mioha TADANO (JAPAN), Mana WATANABE (JAPAN), Seirann MURATA , Takeshi EGUCHI , Kazuaki NISHIYABU (JAPAN), Tetsusei KURASHIKI (JAPAN)Abstract :
Carbon fiber reinforced plastics (CFRP) has been widely used in laminated configurations. However, grid structures have been proposed [1] due to mechanical property problems such as delamination of laminates and insufficient bending rigidity. There are two methods of lattice construction using round rods or rectangular bars stacking the members at arbitrary angles or intersecting the members like a textile. However, there are concerns about increased thickness of the intersection, deformation of the material due to tension, loss of strength, and damage to the contact area. In addition, assuming a joint between the grid structure and the skin, only the members on one side are joined to the skin, so a joint between the members is essential. Therefore, this study focused on the secondary workability of thermoplastic CFRP [2] and attempted to reduce the thickness by half by local thermo-lateral compression forming on the member. By assembling the thermo-lateral compression sections as intersections, a grid structure with uniform overall thickness can be produced. This is expected to increase the joint area between the grid structure and the skin.
In this paper, CF/PEEK round rods were heated by near-infrared ring heaters or electric current and then laterally compressed to investigate their forming behavior. CF/PEEK round rods made by pultrusion forming of unidirectional carbon fiber-reinforced poly-ether-ether-ketone (UD-CF/PEEK) prepreg tape were used as primary formed parts [3]. When CF/PEEK round rods were heated and laterally compressed with a flat punch forming only intersections, the laterally compressed areas became denser, but delamination of the not laterally compressed areas became a problem. This is because the CF/PEEK round rods expanded upon heating and solidified without densification under lateral compression. To expand the lateral compression range and determine the shape, a 3D-shaped punch was designed to form a formed product with a cross-sectional area that is always equal perpendicular to the axial direction. The 3D-shaped punch was able to laterally compress the heated range sufficiently, and delamination was eliminated. However, there are limits to the conditions under which a 3D-shaped punches can be used, and further miniaturization is required. Investigate detailed forming behavior as well as more optimal punch geometry for grid structure fabrication. The mechanical properties of the crossed formed parts will be investigated by performing a bidirectional bending test using an originally designed bidirectional bending test jig that supports and pressurizes the ends of the crossed formed parts at the fulcrums.
In this paper, CF/PEEK round rods were heated by near-infrared ring heaters or electric current and then laterally compressed to investigate their forming behavior. CF/PEEK round rods made by pultrusion forming of unidirectional carbon fiber-reinforced poly-ether-ether-ketone (UD-CF/PEEK) prepreg tape were used as primary formed parts [3]. When CF/PEEK round rods were heated and laterally compressed with a flat punch forming only intersections, the laterally compressed areas became denser, but delamination of the not laterally compressed areas became a problem. This is because the CF/PEEK round rods expanded upon heating and solidified without densification under lateral compression. To expand the lateral compression range and determine the shape, a 3D-shaped punch was designed to form a formed product with a cross-sectional area that is always equal perpendicular to the axial direction. The 3D-shaped punch was able to laterally compress the heated range sufficiently, and delamination was eliminated. However, there are limits to the conditions under which a 3D-shaped punches can be used, and further miniaturization is required. Investigate detailed forming behavior as well as more optimal punch geometry for grid structure fabrication. The mechanical properties of the crossed formed parts will be investigated by performing a bidirectional bending test using an originally designed bidirectional bending test jig that supports and pressurizes the ends of the crossed formed parts at the fulcrums.