Study on High Impact-resistant Stacking Sequence of CFRP Laminated Composites

Research Project

Project/Area Number	01550078
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	材料力学
Research Institution	Takushoku University
Principal Investigator	KASANO Hideaki Tadushoku University, Dept. Mech. Sys. Eng., Associate Prodessor, 工学部, 助教授 (40016663)
Co-Investigator(Kenkyū-buntansha)	KASANO Hideaki Takushoku University, Dept. Mech. Sys. Eng., Associate Professor (40016663)
Project Period (FY)	1989 – 1990
Project Status	Completed (Fiscal Year 1990)
Budget Amount *help	¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 1990: ¥200,000 (Direct Cost: ¥200,000) Fiscal Year 1989: ¥1,800,000 (Direct Cost: ¥1,800,000)
Keywords	CFRP / Laminated Plate / Impact-induced Damage / Delamination / CAI / Air Gun / Scanning Acoustic Mcroscopy / Scanning Electron Microscopy / 層間界面はく離 / 積層複合材 / 界面はく離 / 残存強度 / 衝撃試験機
Research Abstract	The goal of the present research is to show how the impact-induced damage of CFRP of CFRP (Carbon Fiber Reinforced Plastics) is reduced by appropriately selecting the stacking sequence of unidirectional carbon fiber spreーpreg sheets. An air gun type impact testing machine is designed and manufactured to generate impact damage. This testing machine makes it possible to propel the steel balls of diameters 5mm and 10mm with maximum velocities of 160m/sec and 120m/sec, respectively. The impact damage is expected to occur between two layers with different fiber directions accompanied by delaminations. So the specimens of angle-ply laminate composites with [0^ﾟ _6/0^ﾟ _<10>/0^ﾟ _6] are employed, in which 6 kinds of ply-angle such as theta^ﾟ=15, 30, 45, 60, 75 and 90 are selected. In the impact testing, 2 kinds of steel balls mentioned above are propelled with the same velocities of 60.4m/sec. The inside of the specimens flatwise impacted are observed through a scanning acoustic microscopy, and their cross-sections are observed through a scanning electron microscopy as well. Results obtained are summarized as follows : (1) characteristic damage patterns of delaminations are seen on 0^ﾟ/theta^ﾟ and theta^ﾟ/0^ﾟ interfaces where fiber orientations are changed, and the area of the latter is considerably large compared to the former, (2) the damage areas increase with an increasing diameter steel ball or plyangl, (3) many transverse cracks are observed in the cross-sections, (4) cracks corresponding to other delaminations than those mentioned above are also seen, (5) initial compression Young's moduli before and after impact are almost the same. The conclusion is that the fiber oriectations suitably selected contribute to the reduction of the impact-induced damage and the transverse crack initiation must be prevented as well. The future work is to consider this problem from a theoretical point of view.