Study of the dimensional stability of a carbon-fiber-reinforced plastic by the method of laser interferometry
The method of laser interferometry is the most sensitive, precise, and reliable method for measuring microscopic changes in the geometric dimensions of specimens of carbon-plastic, since the measurements are scaled to a natural length — fractions of the wavelength of the laser radiation.
The drift of the geometric dimensions of "dry" and "moist" specimens of carbon-plastic under natural conditions occurs during the first several hours. The sign of the drift differs on different specimens: dry specimens are saturated by moisture and the linear dimensions increase; drying takes place in the case of the moist specimens, i.e. the linear dimensions decrease (see Fig. 3).
Preliminary thermocycling stabilizes the geometric dimensions of carbon-plastics and improves their dimensional stability. The moistening-drying cycle does not increase the dimensional stability of the composite.
The location of the reinforcing fibers in the surface layers affects the dimensional stability of a carbon-plastic only in the case of dry specimens. Less drift occurs in specimens in which the fibers are longitudinally oriented.
Specimens that are stored for a long time and then chemically dried to a constant mass have the same dimensional stability as freshly prepared thermocycled specimens (curves 2–4 and 7, 8 in Fig. 3).
KeywordsRadiation Surface Layer Laser Radiation Natural Condition Geometric Dimension
Unable to display preview. Download preview PDF.
- 1.H. T. Hahn, "Hydrothermal damage in graphite/epoxy laminates," J. Eng. Mater. Technol.,109, No. 1, 3–11 (1987).Google Scholar
- 2.D. E. Bowles, S. S. Tompkins, and G. F. Sikes, "Electron radiation effects on the thermal expansion of graphite resin composites," J. Spacecr. Rockets,23, No. 6, 625–629 (1986).Google Scholar
- 3.S. S. Tompkins, D. E. Bowles, and W. R. Kennedy, "A laser interferometry dilatometry for thermal expansion measure-ments of composites," Proc. 5th Intern. Cong. on Experimental Mechanics. Montreal, June, 1984, pp. 367–376.Google Scholar
- 4.V. A. Grigor'ev, Zh. Zhelkobaev, V. V. Kalendin, V. I. Kukhtevich, V. Ya. Sup'yan, F. G. Frolov, and I. V. Trotsishin, "Optical-range phase meter," Inventor's Certificate No. 1411572 SSSR. Awarded 27.07.84. Otkrytiya. Izobret., No. 27 (1988).Google Scholar
- 5.Zh. Zhelkobaev, V. V. Kalendin, V. I. Kukhtevich, Yu. G. Popov, and A. I. Trubnikov, "Calculation of the passive thermal protection for a laser interferometer," Summary of Documents of the Scientific-Technical Seminar "Phase and polarization measurements of laser radiation and their metrological substantiation," Moscow (1978), pp. 66–68.Google Scholar
- 6.Yu. N. Vygovskii, Zh. Zhelkobaev, V. V. Kalendin, S. S. Sobolev, and I. V. Trotsishin, "Automated laser phase meter," Transactions of the Third All-Union Conference "Precise Measurements of Electrical Quantities," Leningrad (1988), pp. 116–117.Google Scholar
- 7.J. Maiden, R. Gounder, and S. Seehra, "Development of design data on an ultrahigh modulus graphite/epoxy composite for space application," 30th National SAMPE Symp. March (1985), pp. 135–149.Google Scholar