39th Risø International Symposium on Materials Science 'Fatigue of Composite Materials: Microstructure, Mechanics and Methods' | |
High-speed bending-fatigue testing of composite materials | |
Ueki, Y.^1 | |
Reliability Science Research Department, Research and Development Group, Hitachi, Ltd., Japan^1 | |
关键词: Electromagnetic vibrators; Fibre reinforced composites; Finite element vibration analysis; Heat transfer theory; High-speed testing; Resonance tracking; Reversed bending tests; Strain distributions; | |
Others : https://iopscience.iop.org/article/10.1088/1757-899X/388/1/012008/pdf DOI : 10.1088/1757-899X/388/1/012008 |
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来源: IOP | |
【 摘 要 】
A methodology for high-speed fatigue testing, especially for resin materials, including fibre-reinforced composites, was devised and evaluated. To exert periodic stress on a material at a frequency of more than 200 Hz, a specimen (made of glass fibre-epoxy laminate) was fixed as a cantilever to an electromagnetic vibrator and vibrated at its resonant frequency of the first bending mode by using a resonance tracking control. The shape of the specimen was designed with finite-element vibration analysis to obtain a resonant frequency of more than 200 Hz and a desired strain distribution for inducing fatigue damage under a certain stress level. The rise in temperature during the fatigue testing (due to damping loss) was estimated by applying heat-transfer theory and suppressed by external cooling to keep the specimen at room temperature. To confirm the validity of the devised high-speed-testing method, a completely reversed bending test at 1 Hz was also performed with identical specimens. The results from both testing methods (conducted at 230 Hz and 1 Hz, respectively) were plotted on a single power-law curve in an S-N plot. The good agreement between the two plots suggests that fatigue strength in the high- or giga-cycle region of resin and composites can be evaluated in a very short time if temperature is controlled appropriately.
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