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1 Application of High Stiffness and Light Weight FRP Structural Materials Tetsuya NARISAWA, Shigeru AOKI, Norihiko UWABO Abstract - Fiber reinforced plastics (FRP) are one of the high-strength, high-stiffness, and lightweight composite materials. Recently, advanced composite materials so as IsoTruss structure has been developed for alternative structures in the field of mechanical and construction industry. This material which developed by BYU at Utah in USA is made based on the honey comb structures. In this report, we show the following acknowledgments of present study. The first, IsoTruss grid structures have been formed with carbon/ epoxy FRP materials with helically filament-winding (FW) method. The next, influence of the tetrahedron region (pyramidal grid in this structure) on mechanical properties are measured. The third, for the applications of this structure the Christmas tree tower was constructed at campus of Kusiro N. C. T. with connected half a dozen pieces. Key Word: FRP, IsoTruss, Composite Materials, FW forming, Stiffness, Vibration (1) Stiffness/dencity (E 1 /ρ) 10 1 [GPa/(Kg/m 3 )] G-FRP C-FRP(HT) C-FRP(HM) HT-steel Titanium Jurarumine Concrete Wood(Maple) Strength/dencity (σ B /ρ) 10-1 [GPa/(Kg/m 3 )] G-FRP C-FRP(HT) C-FRP(HM) HT-steel Titanium Jurarumine Concrete Wood(Maple) Fig.1 Ratio of modulus and tensile strength to weight of various materials Craft Liner Wave Helical Cylinder (by Narisawa Lab.) Fig.2 Honey comb sandwich structures

Recently, advanced composite materials so as IsoTruss structure has been developed for alternative structures in the field of mechanical and construction industry.

2 2) Fig5 Automatic winding machine (a. KOKUBUN Co. Ltd.) and handmade winding process (b) Mandrel a. b. Winding Fig.6 Manufacturing process of IsoTruss T Oven 150~ h 1.0h Cure cycle Mold release t a. Fig.3 Photo of IsoTruss structure (a.) and 44M, WiFi tower concrete pad + b. special adapters (b. HP by IsoTruss Structure Co.Ltd.) Table.1 Specification of Graphite/Epoxy FRP (in catalog) Tetrahedron region Helical fiber Tetrahedron leg Pass line Longitudinal fiber Table.2 Specification of IsoTruss structure Helical fiber Axial fiber 6-nodes 8-nodes 10-nodes Fig.4 Nodal pattern and pass line of IsoTruss winding process φ56 φ100 φ58 φ ( 580)

) Table.1 Specification of Graphite/Epoxy FRP (in catalog) Tetrahedron region Helical fiber Tetrahedron leg Pass line Longitudinal fiber Table.

3 A B With pyramidal structure Without pyramidal structure Fig.7 Appearance of 6 nodes Iso-Truss test pieces 28.9mm 9 Pitch=450mm φ2.3mm 25mm Pitch=50mm φ58mm φ100mm Fig.8 Appearance pyramidrical structures of IsoTruss (3) Dial gage Clump Adapter Angle indicator Fig.9 Three-points bending experiment unit Fig.10 Torsional experiment unit

4 Angle of twist per unit length [rad] Bending stiffness EI [Nm 2 ] 700 W W/O Com Bending load [N] Fig.11 Result of 3-points bending test Complex Without pyramid With pyramid (4) Table.3 Experimental static and dynamic moduli Static[Nm 2 ] Dynamic[Hz ] Twistng truque [Nm] Fig.12 Result of torsional test Microphone RION NK-50 A B C Type EI GIp 1st 2nd 3rd With pyrami d Without pyrami d Complex Impulse hammer Clump FFT analyzer RION SA-71 Fig.13 Figure of FFT analyzed test setup Natural frequency [Hz] Bending stifness EI [Nm 2 ] Fig.15 Bending and torsional stuffiness and natural frequencies With pyramid Without pyramid Complex Fig.14 Results of impulse hammering test

12 Result of torsional test Microphone RION NK-50 A B C Type EI GIp 1st 2nd 3rd With pyrami d 273 243 85 460 780 Without pyrami d 279 134 110 550 920 Complex 261 109 50 400 650 Impulse hammer Clump

5 Natural frequency [Hz] ζ ζ (5),(6) Fig.16 Experimental and analytical natural frequencies Table.4 Damping ratio ζ obtained by half band width method ( φ Type 1st 2nd 3rd φ A With pyrami d B Without pyrami d C Comple x Fig.17 Draft plan and design Table.5 Damping ratio ζ obtained by free vibration and half band width method ( Number of layers Free vibration Half power method Fig.18 Assembling work ρ ρ ζ Fig.19 Appearance of 4m tower decorated with Christmas ornaments

0 C Comple x 12. 7 14. 7 98. 0 Fig.17 Draft plan and design Table.

6 (7) Fig.22 Mountain bicycle applied IsoTruss displaied in industrial technique festival `Made in Kushiro` Fig.20 Kushiro newspaper ( ) Fig.23 Photograph of participator in `Made in Kushiro` Cross-zone crack Inter laminar abruption Fig.24 Buckling fracture at neck assembly Fig.21 Commitment in various festival Fig.25 Idea of joint assembly Fig.26 Curved shape assembly

Kushiro` Fig.20 Kushiro newspaper (04.12.22) Fig.

7 (8) Thomas J. Weaver and David W. Jensen, Mechanical Characterization of a Graphite/Epoxy IsoTruss., J. Aero. Eng., 23, (2000), Smart W. and David W. Jensen, Flexure of Concrete Beams Reinforced with Advanced Composite Orthogrids., J. Aero. Eng., 23, (1997), 7-15.

, J. Aero. Eng., 23, (2000), 23-35. Smart W. and David W.

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.I.v e pmd Structural Design for Curved Panels by Laminated Composite Materials (Identification of Lamination Parameters Using Modal Testing Method ) Tetsuya NARISAWA, Shohei IWATA Abstract - Using a modal testing