| Project/Area Number |
03555012
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Aerospace engineering
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| Research Institution | The University of Tokyo |
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Principal Investigator |
TAKEDA Nobuo Associate professor Research Center for Advanced Science and Technology The University of Tokyo, 先端科学技術研究センター, 助教授 (10171646)
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| Co-Investigator(Kenkyū-buntansha) |
KISHI Teruo Professor Research Center for Advanced Science and Technology The University of, 先端科学技術研究センター, 教授 (40011085)
小林 昭 東京理科大学, 理工学部機械工学科, 教授 (60013637)
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| Project Period (FY) |
1991 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥12,000,000 (Direct Cost: ¥12,000,000)
Fiscal Year 1993: ¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 1992: ¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 1991: ¥4,200,000 (Direct Cost: ¥4,200,000)
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| Keywords | Sprit Hopkinson Pressure Bar / Impact Loading / Stress-Strain Curve / Stress Pulse / Uniaxial Compression / GFRP / Damage Progress / Damage Mechanism / 応力パルス / 一軸引張り / 複合材料 / 高速変形 / 衝撃損傷 / 計測装置 / パルス制御 / スプリットホプキンソン棒法 |
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| Research Abstract |
The purpose of the present investigation is to develop uniaxial impact testing machines with arbitrary input pulse control capability for characterization of impact damage progress in composites, and to demonstrate its validity for detailed observation of impact compression damage in unidiectionally fiber reinforced composites. Although the machineswere principally based on conventional split Hopkinson pressure bar techniques, wave reflection and transmission were carefully conrolled to obtain arbitrary uniaxial input impact pulse shapes and magnitudes. Impact loading can be stopped atany arbitrary point in a simple dynamic compression stress-strain curve, the composite specimens can be recovered for detailed microscopic observation of surface/sub-surface damage development. Both system hardware and software were developed for friendly use.
Specifically for impact compression damage in unidiectionally glass fiber reinforced unsaturated polyester matrix composites, the following results were obtained :
( 1 ) Compressive strength increases with increasing strain rates, but decreases with increasing temperatures.
( 2 ) Compressive modulus and in-plane shear modulus also increase with increasing strain rates, but decrease with increasing temperatures.
( 3 ) Recovered composite specimens revealed that fiber micro-bucling is a major damage mechanism. The impact damage initiation and progress were clarified for the first time using the present experimental technique.
( 4 ) Based on the experimental results, a new theory for fiber micro-bucling in unidirectional composites was developed by considering nonlinear in-plane shear properties. The theory successfully predicted the strain-rate and temperature dependence of compressive strength obtained experimentally.
The developed testing machines are believeded to be a useful characterization tool for R&D studies of novel impact-resistant materials.
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